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Le Noir de Carlan C, Kaarlejärvi E, De Tender C, Heinecke T, Eskelinen A, Verbruggen E. Shifts in mycorrhizal types of fungi and plants in response to fertilisation, warming and herbivory in a tundra grassland. THE NEW PHYTOLOGIST 2024; 243:1190-1204. [PMID: 38742310 DOI: 10.1111/nph.19816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2023] [Accepted: 04/27/2024] [Indexed: 05/16/2024]
Abstract
Climate warming is severely affecting high-latitude regions. In the Arctic tundra, it may lead to enhanced soil nutrient availability and interact with simultaneous changes in grazing pressure. It is presently unknown how these concurrently occurring global change drivers affect the root-associated fungal communities, particularly mycorrhizal fungi, and whether changes coincide with shifts in plant mycorrhizal types. We investigated changes in root-associated fungal communities and mycorrhizal types of the plant community in a 10-yr factorial experiment with warming, fertilisation and grazing exclusion in a Finnish tundra grassland. The strongest determinant of the root-associated fungal community was fertilisation, which consistently increased potential plant pathogen abundance and had contrasting effects on the different mycorrhizal fungal types, contingent on other treatments. Plant mycorrhizal types went through pronounced shifts, with warming favouring ecto- and ericoid mycorrhiza but not under fertilisation and grazing exclusion. Combination of all treatments resulted in dominance by arbuscular mycorrhizal plants. However, shifts in plant mycorrhizal types vs fungi were mostly but not always aligned in their magnitude and direction. Our results show that our ability to predict shifts in symbiotic and antagonistic fungal communities depend on simultaneous consideration of multiple global change factors that jointly alter plant and fungal communities.
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Affiliation(s)
- Coline Le Noir de Carlan
- Plants and Ecosystems (PLECO), Department of Biology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Elina Kaarlejärvi
- Research Centre for Ecological Change, Organismal and Evolutionary Biology, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki, FI-00014, Finland
| | - Caroline De Tender
- Plant Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Burg. Van Gansberghelaan 96-109, 9820, Merelbeke, Belgium
- Department of Biochemistry and Microbiology, Ghent University, K.L. Ledeganckstraat 35, 9000, Ghent, Belgium
| | - Thilo Heinecke
- Plants and Ecosystems (PLECO), Department of Biology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Anu Eskelinen
- Ecology & Genetics, University of Oulu, PO Box 8000, FI-90014, Oulu, Finland
- Department of Physiological Diversity, Helmholtz Center for Environmental Research - UFZ, Permoserstrasse 15, 04318, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv), Puschstraße 4, 04103, Leipzig, Germany
| | - Erik Verbruggen
- Plants and Ecosystems (PLECO), Department of Biology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
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2
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Wei B, Zhang D, Wang G, Liu Y, Li Q, Zheng Z, Yang G, Peng Y, Niu K, Yang Y. Experimental warming altered plant functional traits and their coordination in a permafrost ecosystem. THE NEW PHYTOLOGIST 2023; 240:1802-1816. [PMID: 37434301 DOI: 10.1111/nph.19115] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 06/13/2023] [Indexed: 07/13/2023]
Abstract
Knowledge about changes in plant functional traits is valuable for the mechanistic understanding of warming effects on ecosystem functions. However, observations have tended to focus on aboveground plant traits, and there is little information about changes in belowground plant traits or the coordination of above- and belowground traits under climate warming, particularly in permafrost ecosystems. Based on a 7-yr field warming experiment, we measured 26 above- and belowground plant traits of four dominant species, and explored community functional composition and trait networks in response to experimental warming in a permafrost ecosystem on the Tibetan Plateau. Experimental warming shifted community-level functional traits toward more acquisitive values, with earlier green-up, greater plant height, larger leaves, higher photosynthetic resource-use efficiency, thinner roots, and greater specific root length and root nutrient concentrations. However, warming had a negligible effect in terms of functional diversity. In addition, warming shifted hub traits which have the highest centrality in the network from specific root area to leaf area. These results demonstrate that above- and belowground traits exhibit consistent adaptive strategies, with more acquisitive traits in warmer environments. Such changes could provide an adaptive advantage for plants in response to environmental change.
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Affiliation(s)
- Bin Wei
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dianye Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Guanqin Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Qinlu Li
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zhihu Zheng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Guibiao Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Yunfeng Peng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Kechang Niu
- Department of Ecology, School of Life Sciences, Nanjing University, Nanjing, 210023, China
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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3
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Schuur EAG, Hicks Pries C, Mauritz M, Pegoraro E, Rodenhizer H, See C, Ebert C. Ecosystem and soil respiration radiocarbon detects old carbon release as a fingerprint of warming and permafrost destabilization with climate change. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220201. [PMID: 37807688 PMCID: PMC10642809 DOI: 10.1098/rsta.2022.0201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 05/09/2023] [Indexed: 10/10/2023]
Abstract
The permafrost region has accumulated organic carbon in cold and waterlogged soils over thousands of years and now contains three times as much carbon as the atmosphere. Global warming is degrading permafrost with the potential to accelerate climate change as increased microbial decomposition releases soil carbon as greenhouse gases. A 19-year time series of soil and ecosystem respiration radiocarbon from Alaska provides long-term insight into changing permafrost soil carbon dynamics in a warmer world. Nine per cent of ecosystem respiration and 23% of soil respiration observations had radiocarbon values more than 50‰ lower than the atmospheric value. Furthermore, the overall trend of ecosystem and soil respiration radiocarbon values through time decreased more than atmospheric radiocarbon values did, indicating that old carbon degradation was enhanced. Boosted regression tree analyses showed that temperature and moisture environmental variables had the largest relative influence on lower radiocarbon values. This suggested that old carbon degradation was controlled by warming/permafrost thaw and soil drying together, as waterlogged soil conditions could protect soil carbon from microbial decomposition even when thawed. Overall, changing conditions increasingly favoured the release of old carbon, which is a definitive fingerprint of an accelerating feedback to climate change as a consequence of warming and permafrost destabilization. This article is part of the Theo Murphy meeting issue 'Radiocarbon in the Anthropocene'.
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Affiliation(s)
- Edward A. G. Schuur
- Center for Ecosystem Science and Society, and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Caitlin Hicks Pries
- Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Marguerite Mauritz
- Biological Sciences, University of Texas at El Paso, 500 West University Avenue, El Paso, TX 79902, USA
| | - Elaine Pegoraro
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Lab, Berkeley, CA, USA
| | | | - Craig See
- Center for Ecosystem Science and Society, and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
| | - Chris Ebert
- Center for Ecosystem Science and Society, and Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
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4
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Rodenhizer H, Natali SM, Mauritz M, Taylor MA, Celis G, Kadej S, Kelley AK, Lathrop ER, Ledman J, Pegoraro EF, Salmon VG, Schädel C, See C, Webb EE, Schuur EAG. Abrupt permafrost thaw drives spatially heterogeneous soil moisture and carbon dioxide fluxes in upland tundra. GLOBAL CHANGE BIOLOGY 2023; 29:6286-6302. [PMID: 37694963 DOI: 10.1111/gcb.16936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 08/16/2023] [Accepted: 08/27/2023] [Indexed: 09/12/2023]
Abstract
Permafrost thaw causes the seasonally thawed active layer to deepen, causing the Arctic to shift toward carbon release as soil organic matter becomes susceptible to decomposition. Ground subsidence initiated by ice loss can cause these soils to collapse abruptly, rapidly shifting soil moisture as microtopography changes and also accelerating carbon and nutrient mobilization. The uncertainty of soil moisture trajectories during thaw makes it difficult to predict the role of abrupt thaw in suppressing or exacerbating carbon losses. In this study, we investigated the role of shifting soil moisture conditions on carbon dioxide fluxes during a 13-year permafrost warming experiment that exhibited abrupt thaw. Warming deepened the active layer differentially across treatments, leading to variable rates of subsidence and formation of thermokarst depressions. In turn, differential subsidence caused a gradient of moisture conditions, with some plots becoming consistently inundated with water within thermokarst depressions and others exhibiting generally dry, but more variable soil moisture conditions outside of thermokarst depressions. Experimentally induced permafrost thaw initially drove increasing rates of growing season gross primary productivity (GPP), ecosystem respiration (Reco ), and net ecosystem exchange (NEE) (higher carbon uptake), but the formation of thermokarst depressions began to reverse this trend with a high level of spatial heterogeneity. Plots that subsided at the slowest rate stayed relatively dry and supported higher CO2 fluxes throughout the 13-year experiment, while plots that subsided very rapidly into the center of a thermokarst feature became consistently wet and experienced a rapid decline in growing season GPP, Reco , and NEE (lower carbon uptake or carbon release). These findings indicate that Earth system models, which do not simulate subsidence and often predict drier active layer conditions, likely overestimate net growing season carbon uptake in abruptly thawing landscapes.
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Affiliation(s)
- Heidi Rodenhizer
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Susan M Natali
- Woodwell Climate Research Center, Falmouth, Massachusetts, USA
| | - Marguerite Mauritz
- Biological Sciences, University of Texas at El Paso, El Paso, Texas, USA
| | - Meghan A Taylor
- CliC International Project Office, World Climate Research Program, Department of Earth, Geographic and Climate Sciences, University of Massachusetts, Amherst, Massachusetts, USA
| | - Gerardo Celis
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
| | - Stephanie Kadej
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Allison K Kelley
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Emma R Lathrop
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Justin Ledman
- Bonanza Creek Long Term Ecological Research Site, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - Elaine F Pegoraro
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, USA
| | - Verity G Salmon
- Environmental Science Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Christina Schädel
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Craig See
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Elizabeth E Webb
- School of Natural Resources and Environment, University of Florida, Gainesville, Florida, USA
| | - Edward A G Schuur
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
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5
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Ogden EL, Cumming SG, Smith SL, Turetsky MR, Baltzer JL. Permafrost thaw induces short-term increase in vegetation productivity in northwestern Canada. GLOBAL CHANGE BIOLOGY 2023; 29:5352-5366. [PMID: 37332117 DOI: 10.1111/gcb.16812] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 05/02/2023] [Indexed: 06/20/2023]
Abstract
Over the past several decades, various trends in vegetation productivity, from increases to decreases, have been observed throughout Arctic-Boreal ecosystems. While some of this variation can be explained by recent climate warming and increased disturbance, very little is known about the impacts of permafrost thaw on productivity across diverse vegetation communities. Active layer thickness data from 135 permafrost monitoring sites along a 10° latitudinal transect of the Northwest Territories, Canada, paired with a Landsat time series of normalized difference vegetation index from 1984 to 2019, were used to quantify the impacts of changing permafrost conditions on vegetation productivity. We found that active layer thickness contributed to the observed variation in vegetation productivity in recent decades in the northwestern Arctic-Boreal, with the highest rates of greening occurring at sites where the near-surface permafrost recently had thawed. However, the greening associated with permafrost thaw was not sustained after prolonged periods of thaw and appeared to diminish after the thaw front extended outside the plants' rooting zone. Highest rates of greening were found at the mid-transect sites, between 62.4° N and 65.2° N, suggesting that more southernly sites may have already surpassed the period of beneficial permafrost thaw, while more northern sites may have yet to reach a level of thaw that supports enhanced vegetation productivity. These results indicate that the response of vegetation productivity to permafrost thaw is highly dependent on the extent of active layer thickening and that increases in productivity may not continue in the coming decades.
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Affiliation(s)
- Emily L Ogden
- Biology Department, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Steven G Cumming
- Department of Wood and Forest Sciences, Laval University, Quebec City, Quebec, Canada
| | - Sharon L Smith
- Geological Survey of Canada, Natural Resources Canada, Ottawa, Ontario, Canada
| | - Merritt R Turetsky
- Ecology and Evolutionary Biology Department, University of Colorado, Boulder, Colorado, USA
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, Colorado, USA
| | - Jennifer L Baltzer
- Biology Department, Wilfrid Laurier University, Waterloo, Ontario, Canada
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6
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Zhang D, Wang L, Qin S, Kou D, Wang S, Zheng Z, Peñuelas J, Yang Y. Microbial nitrogen and phosphorus co-limitation across permafrost region. GLOBAL CHANGE BIOLOGY 2023; 29:3910-3923. [PMID: 37097019 DOI: 10.1111/gcb.16743] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 04/05/2023] [Indexed: 05/03/2023]
Abstract
The status of plant and microbial nutrient limitation have profound impacts on ecosystem carbon cycle in permafrost areas, which store large amounts of carbon and experience pronounced climatic warming. Despite the long-term standing paradigm assumes that cold ecosystems primarily have nitrogen deficiency, large-scale empirical tests of microbial nutrient limitation are lacking. Here we assessed the potential microbial nutrient limitation across the Tibetan alpine permafrost region, using the combination of enzymatic and elemental stoichiometry, genes abundance and fertilization method. In contrast with the traditional view, the four independent approaches congruently detected widespread microbial nitrogen and phosphorus co-limitation in both the surface soil and deep permafrost deposits, with stronger limitation in the topsoil. Further analysis revealed that soil resources stoichiometry and microbial community composition were the two best predictors of the magnitude of microbial nutrient limitation. High ratio of available soil carbon to nutrient and low fungal/bacterial ratio corresponded to strong microbial nutrient limitation. These findings suggest that warming-induced enhancement in soil nutrient availability could stimulate microbial activity, and probably amplify soil carbon losses from permafrost areas.
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Affiliation(s)
- Dianye Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Lu Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Shuqi Qin
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Dan Kou
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Biogeochemistry Research Group, Department of Biological and Environmental Sciences, University of Eastern Finland, Kuopio, Finland
| | - Siyu Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhihu Zheng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Josep Peñuelas
- Consejo Superior de Investigaciones Científicas (CSIC), Global Ecology Unit CREAF-CSIC-UAB (Universitat Autònoma de Barcelona), Barcelona, Spain
- CREAF, Barcelona, Catalonia, Spain
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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7
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Wang X, Wang S, Yang Y, Tian H, Jetten MSM, Song C, Zhu G. Hot moment of N 2O emissions in seasonally frozen peatlands. THE ISME JOURNAL 2023; 17:792-802. [PMID: 36864114 PMCID: PMC10203296 DOI: 10.1038/s41396-023-01389-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 02/15/2023] [Accepted: 02/21/2023] [Indexed: 03/04/2023]
Abstract
Since the start of the Anthropocene, northern seasonally frozen peatlands have been warming at a rate of 0.6 °C per decade, twice that of the Earth's average rate, thereby triggering increased nitrogen mineralization with subsequent potentially large losses of nitrous oxide (N2O) to the atmosphere. Here we provide evidence that seasonally frozen peatlands are important N2O emission sources in the Northern Hemisphere and the thawing periods are the hot moment of annual N2O emissions. The flux during the hot moment of thawing in spring was 1.20 ± 0.82 mg N2O m-2 d-1, significantly higher than that during the other periods (freezing, -0.12 ± 0.02 mg N2O m-2 d-1; frozen, 0.04 ± 0.04 mg N2O m-2 d-1; thawed, 0.09 ± 0.01 mg N2O m-2 d-1) or observed for other ecosystems at the same latitude in previous studies. The observed emission flux is even higher than those of tropical forests, the World's largest natural terrestrial N2O source. Furthermore, based on soil incubation with 15N and 18O isotope tracing and differential inhibitors, heterotrophic bacterial and fungal denitrification was revealed as the main source of N2O in peatland profiles (0-200 cm). Metagenomic, metatranscriptomic, and qPCR assays further revealed that seasonally frozen peatlands have high N2O emission potential, but thawing significantly stimulates expression of genes encoding N2O-producing protein complexes (hydroxylamine dehydrogenase (hao) and nitric oxide reductase (nor)), resulting in high N2O emissions during spring. This hot moment converts seasonally frozen peatlands into an important N2O emission source when it is otherwise a sink. Extrapolation of our data to all northern peatland areas reveals that the hot moment emissions could amount to approximately 0.17 Tg of N2O yr-1. However, these N2O emissions are still not routinely included in Earth system models and global IPCC assessments.
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Affiliation(s)
- Xiaomin Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Shanyun Wang
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093, Beijing, China
| | - Hanqin Tian
- Schiller Institute for Integrated Science and Society, Department of Earth and Environmental Sciences, Boston College, Boston, Chestnut Hill, MA 02467, USA
| | - Mike S M Jetten
- Department of Microbiology, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Changchun Song
- Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, 130102, China
| | - Guibing Zhu
- Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 100085, Beijing, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
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8
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Lee J, Yun J, Yang Y, Jung JY, Lee YK, Yuan J, Ding W, Freeman C, Kang H. Attenuation of Methane Oxidation by Nitrogen Availability in Arctic Tundra Soils. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2647-2659. [PMID: 36719133 DOI: 10.1021/acs.est.2c05228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
CH4 emission in the Arctic has large uncertainty due to the lack of mechanistic understanding of the processes. CH4 oxidation in Arctic soil plays a critical role in the process, whereby removal of up to 90% of CH4 produced in soils by methanotrophs can occur before it reaches the atmosphere. Previous studies have reported on the importance of rising temperatures in CH4 oxidation, but because the Arctic is typically an N-limited system, fewer studies on the effects of inorganic nitrogen (N) have been reported. However, climate change and an increase of available N caused by anthropogenic activities have recently been reported, which may cause a drastic change in CH4 oxidation in Arctic soils. In this study, we demonstrate that excessive levels of available N in soil cause an increase in net CH4 emissions via the reduction of CH4 oxidation in surface soil in the Arctic tundra. In vitro experiments suggested that N in the form of NO3- is responsible for the decrease in CH4 oxidation via influencing soil bacterial and methanotrophic communities. The findings of our meta-analysis suggest that CH4 oxidation in the boreal biome is more susceptible to the addition of N than in other biomes. We provide evidence that CH4 emissions in Arctic tundra can be enhanced by an increase of available N, with profound implications for modeling CH4 dynamics in Arctic regions.
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Affiliation(s)
- Jaehyun Lee
- School of Civil and Environmental Engineering, Yonsei University, Seoul03722, South Korea
| | - Jeongeun Yun
- School of Civil and Environmental Engineering, Yonsei University, Seoul03722, South Korea
| | - Yerang Yang
- School of Civil and Environmental Engineering, Yonsei University, Seoul03722, South Korea
| | - Ji Young Jung
- Korea Polar Research Institute, Incheon21990, South Korea
| | - Yoo Kyung Lee
- Korea Polar Research Institute, Incheon21990, South Korea
| | - Junji Yuan
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing210008, China
| | - Weixin Ding
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing210008, China
| | - Chris Freeman
- School of Natural Sciences, Bangor University, BangorLL57 2UW, U.K
| | - Hojeong Kang
- School of Civil and Environmental Engineering, Yonsei University, Seoul03722, South Korea
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9
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Wang Q, Peng X, Watanabe M, Batkhishig O, Okadera T, Saito Y. Carbon budget in permafrost and non-permafrost regions and its controlling factors in the grassland ecosystems of Mongolia. Glob Ecol Conserv 2023. [DOI: 10.1016/j.gecco.2023.e02373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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10
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Dieleman CM, Day NJ, Holloway JE, Baltzer J, Douglas TA, Turetsky MR. Carbon and nitrogen cycling dynamics following permafrost thaw in the Northwest Territories, Canada. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 845:157288. [PMID: 35839897 DOI: 10.1016/j.scitotenv.2022.157288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Revised: 07/06/2022] [Accepted: 07/07/2022] [Indexed: 06/15/2023]
Abstract
Rapid climate warming across northern high latitudes is leading to permafrost thaw and ecosystem carbon release while simultaneously impacting other biogeochemical cycles including nitrogen. We used a two-year laboratory incubation study to quantify concomitant changes in carbon and nitrogen pool quantity and quality as drivers of potential CO2 production in thawed permafrost soils from eight soil cores collected across the southern Northwest Territories (NWT), Canada. These data were contextualized via in situ annual thaw depth measurements from 2015 to 2019 at 40 study sites that varied in burn history. We found with increasing time since experimental thaw the dissolved carbon and nitrogen pool quality significantly declined, indicating sustained microbial processing and selective immobilization across both pools. Piecewise structural equation modeling revealed CO2 trends were predominantly predicted by initial soil carbon content with minimal influence of dissolved phase carbon. Using these results, we provide a first-order estimate of potential near-surface permafrost soil losses of up to 80 g C m-2 over one year in southern NWT, exceeding regional historic mean primary productivity rates in some areas. Taken together, this research provides mechanistic knowledge needed to further constrain the permafrost‑carbon feedback and parameterize Earth system models, while building on empirical evidence that permafrost soils are at high risk of becoming weaker carbon sinks or even significant carbon sources under a changing climate.
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Affiliation(s)
- Catherine M Dieleman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada; School of Environmental Sciences, University of Guelph, Guelph, Ontario, Canada.
| | - Nicola J Day
- Biology Department, Wilfrid Laurier University, Waterloo, Ontario, Canada; School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Jean E Holloway
- Department of Geography, Environment and Geomatics, University of Ottawa, Ontario, Canada
| | - Jennifer Baltzer
- Biology Department, Wilfrid Laurier University, Waterloo, Ontario, Canada
| | - Thomas A Douglas
- U.S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK, USA
| | - Merritt R Turetsky
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada; Institute of Arctic and Alpine Research, Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, USA
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11
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Liu W, Jiang H, Guo X, Li Y, Xu Z. Time-series monitoring of river hydrochemistry and multiple isotope signals in the Yarlung Tsangpo River reveals a hydrological domination of fluvial nitrate fluxes in the Tibetan Plateau. WATER RESEARCH 2022; 225:119098. [PMID: 36126428 DOI: 10.1016/j.watres.2022.119098] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 06/15/2023]
Abstract
Nutrient element cycling in the Tibetan Plateau, the highest and largest plateau in the world, is sensitive to anthropogenic disturbances and climate change. Studying the spatiotemporal dynamics of reactive nitrogen (N) - predominantly in the form of nitrate (NO3-) - in the plateau is crucial to understand the regional and global N cycles and their feedbacks with climate change. We conducted the first weekly frequency hydro-geochemical monitoring (i.e., discharge, water chemistry, and multiple isotopes) from the upper to the lower reaches of the Yarlung Tsangpo River, the largest river in the plateau, in pronounced wet/dry cycles to reveal the biogeochemical transformations and fluvial fluxes of NO3- response to hydrologic condition. Relative stable NO3- concentration and significant linear correlations between the fluvial NO3- fluxes and the discharge were observed, suggesting that a significant potential NO3- source counterbalanced the diluting effects during the rainy season. The negative correlations between δ15N-NO3- and discharge/NO3- fluxes suggested that the increasing NO3- flux respond to the increasing discharge was mainly from water leaching of 15N-depleted soil sources, rather than 15N-enriched sewage. The isotopic mixing model calculation showed that NO3- fluxes were largely generated in the relatively densely populated middle reaches (56%), of which 74% were from soil sources. The fluxes of the soil sources showed large seasonal variation and peaked in August, with hydrological condition as the primary driver. Based on the critical findings, we put forward a NO3- export conceptual model that integrated anthropogenic and climatic forcings and classified NO3- export mechanisms in river basins into transport-limited and generation-limited regimes. In a transport-limited regime that characterized most river basins in the Tibetan Plateau, fluvial NO3- flux presented a linearly relationship in response to runoff variation. In contrast, in a generation-limited regime, the flux would be largely dependent on the thermodynamic of nitrification.
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Affiliation(s)
- Wenjing Liu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hao Jiang
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 100049, China; Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China
| | - Xiao Guo
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuanchuan Li
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhifang Xu
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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12
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A globally relevant stock of soil nitrogen in the Yedoma permafrost domain. Nat Commun 2022; 13:6074. [PMID: 36241637 PMCID: PMC9568517 DOI: 10.1038/s41467-022-33794-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 09/22/2022] [Indexed: 12/24/2022] Open
Abstract
Nitrogen regulates multiple aspects of the permafrost climate feedback, including plant growth, organic matter decomposition, and the production of the potent greenhouse gas nitrous oxide. Despite its importance, current estimates of permafrost nitrogen are highly uncertain. Here, we compiled a dataset of >2000 samples to quantify nitrogen stocks in the Yedoma domain, a region with organic-rich permafrost that contains ~25% of all permafrost carbon. We estimate that the Yedoma domain contains 41.2 gigatons of nitrogen down to ~20 metre for the deepest unit, which increases the previous estimate for the entire permafrost zone by ~46%. Approximately 90% of this nitrogen (37 gigatons) is stored in permafrost and therefore currently immobile and frozen. Here, we show that of this amount, ¾ is stored >3 metre depth, but if partially mobilised by thaw, this large nitrogen pool could have continental-scale consequences for soil and aquatic biogeochemistry and global-scale consequences for the permafrost feedback.
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13
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Lee JR, Waterman MJ, Shaw JD, Bergstrom DM, Lynch HJ, Wall DH, Robinson SA. Islands in the ice: Potential impacts of habitat transformation on Antarctic biodiversity. GLOBAL CHANGE BIOLOGY 2022; 28:5865-5880. [PMID: 35795907 PMCID: PMC9542894 DOI: 10.1111/gcb.16331] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Accepted: 06/15/2022] [Indexed: 05/04/2023]
Abstract
Antarctic biodiversity faces an unknown future with a changing climate. Most terrestrial biota is restricted to limited patches of ice-free land in a sea of ice, where they are adapted to the continent's extreme cold and wind and exploit microhabitats of suitable conditions. As temperatures rise, ice-free areas are predicted to expand, more rapidly in some areas than others. There is high uncertainty as to how species' distributions, physiology, abundance, and survivorship will be affected as their habitats transform. Here we use current knowledge to propose hypotheses that ice-free area expansion (i) will increase habitat availability, though the quality of habitat will vary; (ii) will increase structural connectivity, although not necessarily increase opportunities for species establishment; (iii) combined with milder climates will increase likelihood of non-native species establishment, but may also lengthen activity windows for all species; and (iv) will benefit some species and not others, possibly resulting in increased homogeneity of biodiversity. We anticipate considerable spatial, temporal, and taxonomic variation in species responses, and a heightened need for interdisciplinary research to understand the factors associated with ecosystem resilience under future scenarios. Such research will help identify at-risk species or vulnerable localities and is crucial for informing environmental management and policymaking into the future.
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Affiliation(s)
- Jasmine R. Lee
- British Antarctic SurveyNERCCambridgeUK
- Securing Antarctica's Environmental Future, School of Biology and Environmental ScienceQueensland University of TechnologyBrisbaneQLDAustralia
| | - Melinda J. Waterman
- Securing Antarctica's Environmental Future, School of Earth, Atmospheric and Life SciencesUniversity of WollongongWollongongNew South WalesAustralia
| | - Justine D. Shaw
- Securing Antarctica's Environmental Future, School of Biology and Environmental ScienceQueensland University of TechnologyBrisbaneQLDAustralia
| | - Dana M. Bergstrom
- Australian Antarctic Division, Department of AgricultureWater and the EnvironmentKingstonTASAustralia
- Global Challenges ProgramUniversity of WollongongWollongongNew South WalesAustralia
| | - Heather J. Lynch
- Department of Ecology and EvolutionStony Brook UniversityStony BrookNew YorkUSA
| | - Diana H. Wall
- Department of Biology and School of Global Environmental SustainabilityColorado State UniversityFort CollinsColoradoUSA
| | - Sharon A. Robinson
- Securing Antarctica's Environmental Future, School of Earth, Atmospheric and Life SciencesUniversity of WollongongWollongongNew South WalesAustralia
- Global Challenges ProgramUniversity of WollongongWollongongNew South WalesAustralia
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14
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Lacroix F, Zaehle S, Caldararu S, Schaller J, Stimmler P, Holl D, Kutzbach L, Göckede M. Mismatch of N release from the permafrost and vegetative uptake opens pathways of increasing nitrous oxide emissions in the high Arctic. GLOBAL CHANGE BIOLOGY 2022; 28:5973-5990. [PMID: 35852443 DOI: 10.1111/gcb.16345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 07/09/2022] [Indexed: 06/15/2023]
Abstract
Biogeochemical cycling in permafrost-affected ecosystems remains associated with large uncertainties, which could impact the Earth's greenhouse gas budget and future climate policies. In particular, increased nutrient availability following permafrost thaw could perturb the greenhouse gas exchange in these systems, an effect largely unexplored until now. Here, we enhance the terrestrial ecosystem model QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system), which simulates fully coupled carbon (C), nitrogen (N) and phosphorus (P) cycles in vegetation and soil, with processes relevant in high latitudes (e.g., soil freezing and snow dynamics). In combination with site-level and satellite-based observations, we use the model to investigate impacts of increased nutrient availability from permafrost thawing in comparison to other climate-induced effects and CO2 fertilization over 1960 to 2018 across the high Arctic. Our simulations show that enhanced availability of nutrients following permafrost thaw account for less than 15% of the total Gross primary productivity increase over the time period, despite simulated N limitation over the high Arctic scale. As an explanation for this weak fertilization effect, observational and model data indicate a mismatch between the timing of peak vegetative growth (week 26-27 of the year, corresponding to the beginning of July) and peak thaw depth (week 32-35, mid-to-late August), resulting in incomplete plant use of nutrients near the permafrost table. The resulting increasing N availability approaching the permafrost table enhances N loss pathways, which leads to rising nitrous oxide (N2 O) emissions in our model. Site-level emission trends of 2 mg N m-2 year-1 on average over the historical time period could therefore predict an emerging increasing source of N2 O emissions following future permafrost thaw in the high Arctic.
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Affiliation(s)
- Fabrice Lacroix
- Biogeochemical Signals (BSI), Max Planck Institute for Biogeochemistry, Jena, Germany
- Climate and Environmental Physics, University of Bern, Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
| | - Sönke Zaehle
- Biogeochemical Signals (BSI), Max Planck Institute for Biogeochemistry, Jena, Germany
| | - Silvia Caldararu
- Biogeochemical Signals (BSI), Max Planck Institute for Biogeochemistry, Jena, Germany
| | - Jörg Schaller
- Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
| | - Peter Stimmler
- Leibniz Centre for Agricultural Landscape Research (ZALF), Müncheberg, Germany
| | - David Holl
- Institute of Soil Science, Center for Earth System Research and Sustainability (CEN), University Hamburg, Hamburg, Germany
| | - Lars Kutzbach
- Institute of Soil Science, Center for Earth System Research and Sustainability (CEN), University Hamburg, Hamburg, Germany
| | - Mathias Göckede
- Biogeochemical Signals (BSI), Max Planck Institute for Biogeochemistry, Jena, Germany
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15
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Microbiogeochemical Traits to Identify Nitrogen Hotspots in Permafrost Regions. NITROGEN 2022. [DOI: 10.3390/nitrogen3030031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Permafrost-affected tundra soils are large carbon (C) and nitrogen (N) reservoirs. However, N is largely bound in soil organic matter (SOM), and ecosystems generally have low N availability. Therefore, microbial induced N-cycling processes and N losses were considered negligible. Recent studies show that microbial N processing rates, inorganic N availability, and lateral N losses from thawing permafrost increase when vegetation cover is disturbed, resulting in reduced N uptake or increased N input from thawing permafrost. In this review, we describe currently known N hotspots, particularly bare patches in permafrost peatland or permafrost soils affected by thermokarst, and their microbiogeochemical characteristics, and present evidence for previously unrecorded N hotspots in the tundra. We summarize the current understanding of microbial N cycling processes that promote the release of the potent greenhouse gas (GHG) nitrous oxide (N2O) and the translocation of inorganic N from terrestrial into aquatic ecosystems. We suggest that certain soil characteristics and microbial traits can be used as indicators of N availability and N losses. Identifying N hotspots in permafrost soils is key to assessing the potential for N release from permafrost-affected soils under global warming, as well as the impact of increased N availability on emissions of carbon-containing GHGs.
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16
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Liu Y, Men M, Peng Z, Houx JH, Peng Y. Nitrogen availability determines ecosystem productivity in response to climate warming. Ecology 2022; 103:e3823. [PMID: 35857189 DOI: 10.1002/ecy.3823] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 06/08/2022] [Indexed: 11/11/2022]
Abstract
One of the major uncertainties for carbon-climate feedback predictions is an inadequate understanding of the mechanisms governing variations in ecosystem productivity response to warming. Temperature and water availability are regarded as the primary controls over the direction and magnitude of warming effects, but some unexplained results signal that our understanding is incomplete. Using two complementary meta-analyses, we present evidence that soil nitrogen (N) availability drives the warming effects on ecosystem productivity more strongly than thermal and hydrological factors over a broad geographical scale. First, by synthesizing temperature manipulation experiments, meta-regression model analysis showed that the warming effect on productivity is mainly driven by its effect on soil N availability. Sites with higher warming-induced increase in N availability were characterized by stronger productivity enhancement and vice versa, suggesting that N is a limiting factor across sites. Second, a synthesis of full-factorial warming×N addition experiments demonstrated that N addition significantly weakened the positive warming effect, because the additional N induced by warming may not further benefit plant growth when N limitation is relieved, providing experimental evidence that N regulates the warming effect. Further, we demonstrated that warming effects on soil N availability were modulated by changes in dissolved organic N and soil microbes. Overall, our findings enrich a new mechanistic understanding of the varying magnitudes of observed productivity response to warming, and the N scaling of warming effects may help constrain climate projections.
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Affiliation(s)
- Yang Liu
- College of Resources and Environmental Sciences/Key Laboratory of Farmland Eco-Environment of Hebei, Hebei Agricultural University, Baoding, China.,State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Mingxin Men
- College of Resources and Environmental Sciences/Key Laboratory of Farmland Eco-Environment of Hebei, Hebei Agricultural University, Baoding, China
| | - Zhengping Peng
- College of Resources and Environmental Sciences/Key Laboratory of Farmland Eco-Environment of Hebei, Hebei Agricultural University, Baoding, China
| | - James H Houx
- Agriculture Research and Technology, National Crop Insurance Services, Overland Park, KS, USA
| | - Yunfeng Peng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
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17
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Yun J, Jung JY, Kwon MJ, Seo J, Nam S, Lee YK, Kang H. Temporal Variations Rather than Long-Term Warming Control Extracellular Enzyme Activities and Microbial Community Structures in the High Arctic Soil. MICROBIAL ECOLOGY 2022; 84:168-181. [PMID: 34498119 DOI: 10.1007/s00248-021-01859-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 09/02/2021] [Indexed: 06/13/2023]
Abstract
In Arctic soils, warming accelerates decomposition of organic matter and increases emission of greenhouse gases (GHGs), contributing to a positive feedback to climate change. Although microorganisms play a key role in the processes between decomposition of organic matter and GHGs emission, the effects of warming on temporal responses of microbial activity are still elusive. In this study, treatments of warming and precipitation were conducted from 2012 to 2018 in Cambridge Bay, Canada. Soils of organic and mineral layers were collected monthly from June to September in 2018 and analyzed for extracellular enzyme activities and bacterial community structures. The activity of hydrolases was the highest in June and decreased thereafter over summer in both organic and mineral layers. Bacterial community structures changed gradually over summer, and the responses were distinct depending on soil layers and environmental factors; water content and soil temperature affected the shift of bacterial community structures in both layers, whereas bacterial abundance, dissolved organic carbon, and inorganic nitrogen did so in the organic layer only. The activity of hydrolases and bacterial community structures did not differ significantly among treatments but among months. Our results demonstrate that temporal variations may control extracellular enzyme activities and microbial community structure rather than the small effect of warming over a long period in high Arctic soil. Although the effects of the treatments on microbial activity were minor, our study provides insight that microbial activity may increase due to an increase in carbon availability, if the growing season is prolonged in the Arctic.
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Affiliation(s)
- Jeongeun Yun
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Korea
| | - Ji Young Jung
- Korea Polar Research Institute, Incheon, 21990, Korea
| | - Min Jung Kwon
- Laboratoire Des Sciences du Climat Et de I'Environnement, LSCE, 91191, Gif sur Yvette, France
| | - Juyoung Seo
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Korea
| | - Sungjin Nam
- Korea Polar Research Institute, Incheon, 21990, Korea
| | - Yoo Kyung Lee
- Korea Polar Research Institute, Incheon, 21990, Korea
| | - Hojeong Kang
- School of Civil and Environmental Engineering, Yonsei University, Seoul, 03722, Korea.
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18
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Abstract
Studies for the northern high latitudes suggest that, in the near term, increased vegetation uptake may offset permafrost carbon losses, but over longer time periods, permafrost carbon decomposition causes a net loss of carbon. Here, we assess the impact of a coupled carbon and nitrogen cycle on the simulations of these carbon fluxes. We present results from JULES-IMOGEN—a global land surface model coupled to an intermediate complexity climate model with vertically resolved soil biogeochemistry. We quantify the impact of nitrogen fertilisation from thawing permafrost on the carbon cycle and compare it with the loss of permafrost carbon. Projections show that the additional fertilisation reduces the high latitude vegetation nitrogen limitation and causes an overall increase in vegetation carbon uptake. This is a few Petagrams of carbon (Pg C) by year 2100, increasing to up to 40 Pg C by year 2300 for the RCP8.5 concentration scenario and adds around 50% to the projected overall increase in vegetation carbon in that region. This nitrogen fertilisation results in a negative (stabilising) feedback on the global mean temperature, which could be equivalent in magnitude to the positive (destabilising) temperature feedback from the loss of permafrost carbon. This balance depends on the future scenario and initial permafrost carbon. JULES-IMOGEN describes one representation of the changes in Arctic carbon and nitrogen cycling in response to climate change. However there are uncertainties in the modelling framework, model parameterisation and missing processes which, when assessed, will provide a more complete picture of the balance between stabilising and destabilising feedbacks.
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19
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Increased Arctic NO3− Availability as a Hydrogeomorphic Consequence of Permafrost Degradation and Landscape Drying. NITROGEN 2022. [DOI: 10.3390/nitrogen3020021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Climate-driven permafrost thaw alters the strongly coupled carbon and nitrogen cycles within the Arctic tundra, influencing the availability of limiting nutrients including nitrate (NO3−). Researchers have identified two primary mechanisms that increase nitrogen and NO3− availability within permafrost soils: (1) the ‘frozen feast’, where previously frozen organic material becomes available as it thaws, and (2) ‘shrubification’, where expansion of nitrogen-fixing shrubs promotes increased soil nitrogen. Through the synthesis of original and previously published observational data, and the application of multiple geospatial approaches, this study investigates and highlights a third mechanism that increases NO3− availability: the hydrogeomorphic evolution of polygonal permafrost landscapes. Permafrost thaw drives changes in microtopography, increasing the drainage of topographic highs, thus increasing oxic conditions that promote NO3− production and accumulation. We extrapolate relationships between NO3− and soil moisture in elevated topographic features within our study area and the broader Alaskan Coastal Plain and investigate potential changes in NO3− availability in response to possible hydrogeomorphic evolution scenarios of permafrost landscapes. These approximations indicate that such changes could increase Arctic tundra NO3− availability by ~250–1000%. Thus, hydrogeomorphic changes that accompany continued permafrost degradation in polygonal permafrost landscapes will substantially increase soil pore water NO3− availability and boost future fertilization and productivity in the Arctic.
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20
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Simulating Increased Permafrost Peatland Plant Productivity in Response to Belowground Fertilisation Using the JULES Land Surface Model. NITROGEN 2022. [DOI: 10.3390/nitrogen3020018] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Several experimental studies have shown that climate-warming-induced permafrost thaw releases previously unavailable nitrogen which can lower nitrogen limitation, increase plant productivity, and counteract some of the carbon released from thawing permafrost. The net effect of this belowground fertilisation effect remains debated and is yet to be included in Earth System models. Here, we included the impact of thaw-related nitrogen fertilisation on vegetation in the Joint UK Land Environment Simulator (JULES) land surface model for the first time. We evaluated its ability to replicate a three-year belowground fertilisation experiment in which JULES was generally able to simulate belowground fertilisation in accordance with the observations. We also ran simulations under future climate to investigate how belowground nitrogen fertilisation affects the carbon cycle. These simulations indicate an increase in plant-available inorganic nitrogen at the thaw front by the end of the century with only the productivity of deep-rooting plants increasing in response. This suggests that deep-rooting species will have a competitive advantage under future climate warming. Our results also illustrate the capacity to simulate belowground nitrogen fertilisation at the thaw front in a global land surface model, leading towards a more complete representation of coupled carbon and nitrogen dynamics in the northern high latitudes.
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21
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Kashi NN, Hobbie EA, Varner RK, Wymore AS, Ernakovich JG, Giesler R. Nutrients Alter Methane Production and Oxidation in a Thawing Permafrost Mire. Ecosystems 2022. [DOI: 10.1007/s10021-022-00758-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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22
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Burnett MS, Schütte UM, Harms TK. WIDESPREAD CAPACITY FOR DENITRIFICATION ACROSS A BOREAL FOREST LANDSCAPE. BIOGEOCHEMISTRY 2022; 158:215-232. [PMID: 36186670 PMCID: PMC9518932 DOI: 10.1007/s10533-022-00895-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 01/18/2022] [Indexed: 06/16/2023]
Abstract
A warming climate combined with frequent and severe fires cause permafrost to thaw, especially in the region of discontinuous permafrost, where soil temperatures may only be a few degrees below 0 °C. Soil thaw releases carbon (C) and nitrogen (N) into the actively cycling pools, and whereas C emissions following permafrost thaw are well documented, the fates of N remain unclear. Denitrification could release N from ecosystems as nitrous oxide (N2O) or nitrogen gas (N2), but the contributions of these processes to the high-latitude N cycle remain uncertain. We quantified microbial capacity for denitrification and N2O production in boreal soils, lakes, and streams using anoxic C- and N-amended assays, and assessed correlates of denitrifying enzyme activity (DEA) in Interior Alaska. Riparian soils and stream sediments supported the highest potential rates of denitrification, upland soils were intermediate, and lakes supported lower rates, whereas deep permafrost soils supported little denitrification. Time since fire had no effect on denitrification potential in upland soils. Across all landscape positions, DEA was negatively correlated with ammonium pools. Within each landscape position, potential rate of denitrification increased with soil or sediment organic matter content. Widespread N loss to denitrification in boreal forests could constrain the capacity for N-limited primary producers to maintain C stocks in soils following permafrost thaw.
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Affiliation(s)
- Melanie S. Burnett
- Institute of Arctic Biology and Department of Biology & Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States of America
- Department of Earth and Planetary Science, McGill University, Montréal, Quebec H3A 2A7, Canada
| | - Ursel M.E. Schütte
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States of America
| | - Tamara K. Harms
- Institute of Arctic Biology and Department of Biology & Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska 99775, United States of America
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23
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Heim RJ, Heim W, Bültmann H, Kamp J, Rieker D, Yurtaev A, Hölzel N. Fire disturbance promotes biodiversity of plants, lichens and birds in the Siberian subarctic tundra. GLOBAL CHANGE BIOLOGY 2022; 28:1048-1062. [PMID: 34706133 DOI: 10.1111/gcb.15963] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Accepted: 10/06/2021] [Indexed: 06/13/2023]
Abstract
Fire shapes the world's terrestrial ecosystems and has been influencing biodiversity patterns for millennia. Anthropogenic drivers alter fire regimes. Wildfires can amplify changes in the structure, biodiversity and functioning of the fast-warming tundra ecosystem. However, there is little evidence available, how these fires affect species diversity and community composition of tundra ecosystems over the long term. We studied long-term fire effects on community composition and diversity at different trophic levels of the food web in the subarctic tundra of Western Siberia. In a space-for-time approach we compared three large fire scars (>44, 28 and 12 years old) to unburnt controls. We found that diversity (measured as species richness, Shannon index and evenness) of vascular and non-vascular plants and birds was strongly affected by fire, with the greatest species richness of plants and birds for the intermediate-age fire scar (28 years). Species composition of plants and birds still differed from that of the control >44 years after fire. Increased deciduous shrub cover was related to species richness of all plants in a hump-shaped manner. The proportion of southern (taiga) bird species was highest in the oldest fire scar, which had the highest shrub cover. We conclude that tundra fires have long-term legacies with regard to species diversity and community composition. They may also increase landscape-scale species richness and facilitate range expansions of more southerly distributed species to the subarctic tundra ecosystem.
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Affiliation(s)
- Ramona J Heim
- Institute of Landscape Ecology, University of Münster, Münster, Germany
| | - Wieland Heim
- Institute of Landscape Ecology, University of Münster, Münster, Germany
- Department of Biology, University of Turku, Turku, Finland
| | - Helga Bültmann
- Institute of Landscape Ecology, University of Münster, Münster, Germany
| | - Johannes Kamp
- Department of Conservation Biology, University of Göttingen, Göttingen, Germany
| | - Daniel Rieker
- Institute for Ecology, Evolution and Diversity, Goethe University Frankfurt, Frankfurt, Germany
| | - Andrey Yurtaev
- Research Institute of Ecology and Natural Resources Management, Tyumen State University, Tyumen, Russia
| | - Norbert Hölzel
- Institute of Landscape Ecology, University of Münster, Münster, Germany
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24
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Wu L, Yang F, Feng J, Tao X, Qi Q, Wang C, Schuur EAG, Bracho R, Huang Y, Cole JR, Tiedje JM, Zhou J. Permafrost thaw with warming reduces microbial metabolic capacities in subsurface soils. Mol Ecol 2021; 31:1403-1415. [PMID: 34878672 DOI: 10.1111/mec.16319] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 11/04/2021] [Accepted: 12/01/2021] [Indexed: 01/27/2023]
Abstract
Microorganisms are major constituents of the total biomass in permafrost regions, whose underlain soils are frozen for at least two consecutive years. To understand potential microbial responses to climate change, here we examined microbial community compositions and functional capacities across four soil depths in an Alaska tundra site. We showed that a 5-year warming treatment increased soil thaw depth by 25.7% (p = .011) within the deep organic layer (15-25 cm). Concurrently, warming reduced 37% of bacterial abundance and 64% of fungal abundances in the deep organic layer, while it did not affect microbial abundance in other soil layers (i.e., 0-5, 5-15, and 45-55 cm). Warming treatment altered fungal community composition and microbial functional structure (p < .050), but not bacterial community composition. Using a functional gene array, we found that the relative abundances of a variety of carbon (C)-decomposing, iron-reducing, and sulphate-reducing genes in the deep organic layer were decreased, which was not observed by the shotgun sequencing-based metagenomics analysis of those samples. To explain the reduced metabolic capacities, we found that warming treatment elicited higher deterministic environmental filtering, which could be linked to water-saturated time, soil moisture, and soil thaw duration. In contrast, plant factors showed little influence on microbial communities in subsurface soils below 15 cm, despite a 25.2% higher (p < .05) aboveground plant biomass by warming treatment. Collectively, we demonstrate that microbial metabolic capacities in subsurface soils are reduced, probably arising from enhanced thaw by warming.
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Affiliation(s)
- Linwei Wu
- Department of Microbiology and Plant Biology, School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA
| | - Felix Yang
- Department of Microbiology and Plant Biology, School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA
| | - Jiajie Feng
- Department of Microbiology and Plant Biology, School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA
| | - Xuanyu Tao
- Department of Microbiology and Plant Biology, School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA
| | - Qi Qi
- School of Environment, State Key Joint Laboratory of Environment Simulation and Pollution Control, Tsinghua University, Beijing, China
| | - Cong Wang
- Department of Microbiology and Plant Biology, School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA
| | - Edward A G Schuur
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, Arizona, USA
| | - Rosvel Bracho
- Department of Biology, School of Forest Resources and Conservation, University of Florida, Gainesville, Florida, USA
| | - Yi Huang
- College of Environmental Science and Engineering, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Peking University, Beijing, China
| | - James R Cole
- Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, USA
| | - James M Tiedje
- Center for Microbial Ecology, Michigan State University, East Lansing, Michigan, USA
| | - Jizhong Zhou
- Department of Microbiology and Plant Biology, School of Civil Engineering and Environmental Sciences, Institute for Environmental Genomics, University of Oklahoma, Norman, Oklahoma, USA.,Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, California, USA
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25
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Yang G, Peng Y, Abbott BW, Biasi C, Wei B, Zhang D, Wang J, Yu J, Li F, Wang G, Kou D, Liu F, Yang Y. Phosphorus rather than nitrogen regulates ecosystem carbon dynamics after permafrost thaw. GLOBAL CHANGE BIOLOGY 2021; 27:5818-5830. [PMID: 34390614 DOI: 10.1111/gcb.15845] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/19/2021] [Accepted: 08/02/2021] [Indexed: 05/27/2023]
Abstract
Ecosystem carbon (C) dynamics after permafrost thaw depends on more than just climate change since soil nutrient status may also impact ecosystem C balance. It has been advocated that nitrogen (N) release upon permafrost thaw could promote plant growth and thus offset soil C loss. However, compared with the widely accepted C-N interactions, little is known about the potential role of soil phosphorus (P) availability. We combined 3-year field observations along a thaw sequence (constituted by four thaw stages, i.e., non-collapse and 5, 14, and 22 years since collapse) with an in-situ fertilization experiment (included N and P additions at the level of 10 g N m-2 year-1 and 10 g P m-2 year-1 ) to evaluate ecosystem C-nutrient interactions upon permafrost thaw. We found that changes in soil P availability rather than N availability played an important role in regulating gross primary productivity and net ecosystem productivity along the thaw sequence. The fertilization experiment confirmed that P addition had stronger effects on plant growth than N addition in this permafrost ecosystem. These two lines of evidence highlight the crucial role of soil P availability in altering the trajectory of permafrost C cycle under climate warming.
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Affiliation(s)
- Guibiao Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yunfeng Peng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Benjamin W Abbott
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, USA
| | - Christina Biasi
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Bin Wei
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dianye Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Jun Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Jianchun Yu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Fei Li
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Guanqin Wang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dan Kou
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Futing Liu
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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26
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Heslop CB, Ruess RW, Kielland K, Bret‐Harte MS. Soil enzymes illustrate the effects of alder nitrogen fixation on soil carbon processes in arctic and boreal ecosystems. Ecosphere 2021. [DOI: 10.1002/ecs2.3818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Calvin B. Heslop
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska 99775 USA
| | - Roger W. Ruess
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska 99775 USA
| | - Knut Kielland
- Institute of Arctic Biology University of Alaska Fairbanks Fairbanks Alaska 99775 USA
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27
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Yu Y, Liu L, Wang J, Zhang Y, Xiao C. Effects of warming on the bacterial community and its function in a temperate steppe. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 792:148409. [PMID: 34146803 DOI: 10.1016/j.scitotenv.2021.148409] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/03/2021] [Accepted: 06/08/2021] [Indexed: 06/12/2023]
Abstract
As a significant environmental issue, global warming will have a significant impact on soil microorganisms, especially soil bacteria. However, the effects of warming on the network structure of bacterial communities and the function of ecosystems remain unclear. Therefore, we examined the effects of three-year simulated field warming on the complexity of soil bacterial communities and predicted functions in a temperate steppe of Inner Mongolia. Warming significantly increased the α-diversity of bacteria in 2018 but did not affect it in 2019 and 2020. Warming increased network complexity and stability and keystone taxa, and these bacterial taxa also associated more closely with each other, indicating that the protection of interactions between bacterial taxa is very important for the conservation of biodiversity. Warming significantly increased aerobic chemoheterotrophy, ureolysis, and chemoheterotrophy, suggesting that warming increased the ability of bacteria to decompose organic matter and the emission of greenhouse gases, such as CO2 and CH4. Collectively, warming will alter soil bacterial community structure and its potential functions, further affecting key functions in grassland belowground ecosystems.
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Affiliation(s)
- Yang Yu
- College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Lu Liu
- College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Jing Wang
- College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Yushu Zhang
- College of Life and Environmental Sciences, Minzu University of China, Beijing, China
| | - Chunwang Xiao
- College of Life and Environmental Sciences, Minzu University of China, Beijing, China.
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28
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Pold G, Baillargeon N, Lepe A, Rastetter EB, Sistla SA. Warming effects on arctic tundra biogeochemistry are limited but habitat‐dependent: a meta‐analysis. Ecosphere 2021. [DOI: 10.1002/ecs2.3777] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Grace Pold
- Natural Resources Management & Environmental Sciences College of Agriculture, Food & Environmental Sciences California Polytechnic State University San Luis Obispo California USA
| | - Natalie Baillargeon
- Smith College Northampton Massachusetts USA
- Woodwell Climate Research Center Woods Hole Massachusetts USA
| | - Adan Lepe
- Amherst College Amherst Massachusetts USA
| | - Edward B. Rastetter
- Marine Biological Laboratories The Ecosystems Center Woods Hole Massachusetts USA
| | - Seeta A. Sistla
- Natural Resources Management & Environmental Sciences College of Agriculture, Food & Environmental Sciences California Polytechnic State University San Luis Obispo California USA
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29
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Webster AJ, Douglas TA, Regier P, Scheuerell MD, Harms TK. Multi-Scale Temporal Patterns in Stream Biogeochemistry Indicate Linked Permafrost and Ecological Dynamics of Boreal Catchments. Ecosystems 2021. [DOI: 10.1007/s10021-021-00709-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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30
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Homyak PM, Slessarev EW, Hagerty S, Greene AC, Marchus K, Dowdy K, Iverson S, Schimel JP. Amino acids dominate diffusive nitrogen fluxes across soil depths in acidic tussock tundra. THE NEW PHYTOLOGIST 2021; 231:2162-2173. [PMID: 33662154 DOI: 10.1111/nph.17315] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 02/18/2021] [Indexed: 06/12/2023]
Abstract
Organic nitrogen (N) is abundant in soils, but early conceptual frameworks considered it nonessential for plant growth. It is now well recognised that plants have the potential to take up organic N. However, it is still unclear whether plants supplement their N requirements by taking up organic N in situ: at what rate is organic N diffusing towards roots and are plants taking it up? We combined microdialysis with live-root uptake experiments to measure amino acid speciation and diffusion rates towards roots of Eriophorum vaginatum. Amino acid diffusion rates (321 ng N cm-2 h-1 ) were c. 3× higher than those for inorganic N. Positively charged amino acids made up 68% of the N diffusing through soils compared with neutral and negatively charged amino acids. Live-root uptake experiments confirmed that amino acids are taken up by plants (up to 1 µg N g-1 min-1 potential net uptake). Amino acids must be considered when forecasting plant-available N, especially when they dominate the N supply, and when acidity favours proteolysis over net N mineralisation. Determining amino acid production pathways and supply rates will become increasingly important in projecting the extent and consequences of shrub expansion, especially considering the higher C : N ratio of plants relative to soil.
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Affiliation(s)
- Peter M Homyak
- Department of Environmental Sciences, University of California, Riverside, CA, 92521, USA
| | - Eric W Slessarev
- Department of Ecology, Evolution, and Marine Biology and Earth Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Shannon Hagerty
- Department of Ecology, Evolution, and Marine Biology and Earth Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Aral C Greene
- Department of Environmental Sciences, University of California, Riverside, CA, 92521, USA
| | - Kenneth Marchus
- Department of Ecology, Evolution, and Marine Biology and Earth Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Kelsey Dowdy
- Department of Ecology, Evolution, and Marine Biology and Earth Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Sadie Iverson
- Department of Ecology, Evolution, and Marine Biology and Earth Research Institute, University of California, Santa Barbara, CA, 93106, USA
| | - Joshua P Schimel
- Department of Ecology, Evolution, and Marine Biology and Earth Research Institute, University of California, Santa Barbara, CA, 93106, USA
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31
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Standen KM, Baltzer JL. Permafrost condition determines plant community composition and community-level foliar functional traits in a boreal peatland. Ecol Evol 2021; 11:10133-10146. [PMID: 34367564 PMCID: PMC8328418 DOI: 10.1002/ece3.7818] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 04/23/2021] [Accepted: 05/28/2021] [Indexed: 11/05/2022] Open
Abstract
Boreal peatlands are critical ecosystems globally because they house 30%-40% of terrestrial carbon (C), much of which is stored in permafrost soil vulnerable to climate warming-induced thaw. Permafrost thaw leads to thickening of the active (seasonally thawed) layer and alters nutrient and light availability. These physical changes may influence community-level plant functional traits through intraspecific trait variation and/or species turnover. As permafrost thaw is expected to cause an efflux of carbon dioxide (CO2) and methane (CH4) from the soil to the atmosphere, it is important to understand thaw-induced changes in plant community productivity to evaluate whether these changes may offset some of the anticipated increases in C emissions. To this end, we collected vascular plant community composition and foliar functional trait data along gradients in aboveground tree biomass and active layer thickness (ALT) in a rapidly thawing boreal peatland, with the expectation that changes in above- and belowground conditions are indicative of altered resource availability. We aimed to determine whether community-level traits vary across these gradients, and whether these changes are dominated by intraspecific trait variation, species turnover, or both. Our results highlight that variability in community-level traits was largely attributable to species turnover and that both community composition and traits were predominantly driven by ALT. Specifically, thicker active layers associated with permafrost-free peatlands (i.e., bogs and fens) shifted community composition from slower-growing evergreen shrubs to faster-growing graminoids and forbs with a corresponding shift toward more productive trait values. The results from this rapidly thawing peatland suggest that continued warming-induced permafrost thaw and thermokarst development alter plant community composition and community-level traits and thus ecosystem productivity. Increased productivity may help to mitigate anticipated CO2 efflux from thawing permafrost, at least in the short term, though this response may be swamped by increase CH4 release.
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32
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Pegoraro EF, Mauritz ME, Ogle K, Ebert CH, Schuur EAG. Lower soil moisture and deep soil temperatures in thermokarst features increase old soil carbon loss after 10 years of experimental permafrost warming. GLOBAL CHANGE BIOLOGY 2021; 27:1293-1308. [PMID: 33305441 DOI: 10.1111/gcb.15481] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 09/05/2020] [Accepted: 10/20/2020] [Indexed: 06/12/2023]
Abstract
Almost half of the global terrestrial soil carbon (C) is stored in the northern circumpolar permafrost region, where air temperatures are increasing two times faster than the global average. As climate warms, permafrost thaws and soil organic matter becomes vulnerable to greater microbial decomposition. Long-term soil warming of ice-rich permafrost can result in thermokarst formation that creates variability in environmental conditions. Consequently, plant and microbial proportional contributions to ecosystem respiration may change in response to long-term soil warming. Natural abundance δ13 C and Δ14 C of aboveground and belowground plant material, and of young and old soil respiration were used to inform a mixing model to partition the contribution of each source to ecosystem respiration fluxes. We employed a hierarchical Bayesian approach that incorporated gross primary productivity and environmental drivers to constrain source contributions. We found that long-term experimental permafrost warming introduced a soil hydrology component that interacted with temperature to affect old soil C respiration. Old soil C loss was suppressed in plots with warmer deep soil temperatures because they tended to be wetter. When soil volumetric water content significantly decreased in 2018 relative to 2016 and 2017, the dominant respiration sources shifted from plant aboveground and young soil respiration to old soil respiration. The proportion of ecosystem respiration from old soil C accounted for up to 39% of ecosystem respiration and represented a 30-fold increase compared to the wet-year average. Our findings show that thermokarst formation may act to moderate microbial decomposition of old soil C when soil is highly saturated. However, when soil moisture decreases, a higher proportion of old soil C is vulnerable to decomposition and can become a large flux to the atmosphere. As permafrost systems continue to change with climate, we must understand the thresholds that may propel these systems from a C sink to a source.
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Affiliation(s)
- Elaine F Pegoraro
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Marguerite E Mauritz
- Ecology and Evolutionary Biology, The University of Texas at El Paso, El Paso, TX, USA
| | - Kiona Ogle
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- School of Informatics, Computing, and Cyber Systems, Northern Arizona University, Flagstaff, AZ, USA
| | - Christopher H Ebert
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Edward A G Schuur
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, USA
- Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
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33
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Wu Y, Wang S, Ni Z, Li H, May L, Pu J. Emerging water pollution in the world's least disturbed lakes on Qinghai-Tibetan Plateau. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2021; 272:116032. [PMID: 33218770 DOI: 10.1016/j.envpol.2020.116032] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 10/15/2020] [Accepted: 11/05/2020] [Indexed: 06/11/2023]
Abstract
Qinghai-Tibet Plateau (QTP) Lake Region has largest abundance and size distribution of lakes in China. Being relatively away from major human activities, the water quality of these lakes has not attracted concerns in the past. However, dramatic climate change and intensified anthropogenic activities over the past 30 years have exerted multiple pressures on the water environment of the lakes, resulting in elevated nutrient concentrations in major freshwater lakes of the region. Rapid water quality deterioration and eutrophication of the lakes were first found in Lake Hurleg in the northeast of the plateau. Analyses of driving forces associated with these changes indicate that both the intrinsic characteristics of the QTP lakes and climate change were responsible for the vulnerability to human activities than other lakes in different regions of China, with accelerated urbanization and extensive economic development in the lake basin playing a decisive role in creating water pollution events. Under combination pressures from both natural and anthropogenic effect, the increasing rate of nutrient concentrations in Lake Hurleg has been 53-346 times faster than in Lake Taihu and Lake Dianchi during the deterioration stage. The result suggests the current development mode of Lake Hurleg basin is not suitable for setting protection targets for the QTP lake region more broadly due to its extremely poor environmental carrying capacity. To stop worsening the lake water environment condition, it is necessary to review the achievements made and lessons learned from China's fight against lake pollution and take immediate measures, inform policies into the development mode in the QTP lake region, and avoid irreversible consequences and ensure good water quality in the "Asian Water Tower."
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Affiliation(s)
- Yue Wu
- Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China; National Engineering Laboratory for Lake Pollution Control and Ecological Restoration, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Shengrui Wang
- Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China; Technology Research Center of Water Science, Beijing Normal University at Zhuhai, Zhuhai, 519087, China.
| | - Zhaokui Ni
- Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China
| | - Hong Li
- Lancaster Environment Centre, Lancaster University, Library Avenue, LA1 4YQ, UK; UK Centre for Ecology & Hydrology, Wallingford, OX108BB, UK
| | - Linda May
- UK Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK
| | - Jia Pu
- Engineering Research Center of Ministry of Education on Groundwater Pollution Control and Remediation, College of Water Sciences, Beijing Normal University, Beijing, 100875, China
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34
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Hetz SA, Horn MA. Burkholderiaceae Are Key Acetate Assimilators During Complete Denitrification in Acidic Cryoturbated Peat Circles of the Arctic Tundra. Front Microbiol 2021; 12:628269. [PMID: 33613495 PMCID: PMC7892595 DOI: 10.3389/fmicb.2021.628269] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 01/18/2021] [Indexed: 01/23/2023] Open
Abstract
Cryoturbated peat circles (pH 4) in the Eastern European Tundra harbor up to 2 mM pore water nitrate and emit the greenhouse gas N2O like heavily fertilized agricultural soils in temperate regions. The main process yielding N2O under oxygen limited conditions is denitrification, which is the sequential reduction of nitrate/nitrite to N2O and/or N2. N2O reduction to N2 is impaired by pH < 6 in classical model denitrifiers and many environments. Key microbes of peat circles are important but largely unknown catalysts for C- and N-cycling associated N2O fluxes. Thus, we hypothesized that the peat circle community includes hitherto unknown taxa and is essentially unable to efficiently perform complete denitrification, i.e., reduce N2O, due to a low in situ pH. 16S rRNA analysis indicated a diverse active community primarily composed of the bacterial class-level taxa Alphaproteobacteria, Acidimicrobiia, Acidobacteria, Verrucomicrobiae, and Bacteroidia, as well as archaeal Nitrososphaeria. Euryarchaeota were not detected. 13C2- and 12C2-acetate supplemented anoxic microcosms with endogenous nitrate and acetylene at an in situ near pH of 4 were used to assess acetate dependent carbon flow, denitrification and N2O production. Initial nitrate and acetate were consumed within 6 and 11 days, respectively, and primarily converted to CO2 and N2, suggesting complete acetate fueled denitrification at acidic pH. Stable isotope probing coupled to 16S rRNA analysis via Illumina MiSeq amplicon sequencing identified acetate consuming key players of the family Burkholderiaceae during complete denitrification correlating with Rhodanobacter spp. The archaeal community consisted primarily of ammonia-oxidizing Archaea of Nitrososphaeraceae, and was stable during the incubation. The collective data indicate that peat circles (i) host acid-tolerant denitrifiers capable of complete denitrification at pH 4-5.5, (ii) other parameters like carbon availability rather than pH are possible reasons for high N2O emissions in situ, and (iii) Burkholderiaceae are responsive key acetate assimilators co-occurring with Rhodanobacter sp. during denitrification, suggesting both organisms being associated with acid-tolerant denitrification in peat circles.
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Affiliation(s)
- Stefanie A Hetz
- Institute of Microbiology, Leibniz University Hannover, Hannover, Germany
| | - Marcus A Horn
- Institute of Microbiology, Leibniz University Hannover, Hannover, Germany
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35
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Variation in Fine Root Characteristics and Nutrient Dynamics Across Alaskan Ecosystems. Ecosystems 2020. [DOI: 10.1007/s10021-020-00583-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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36
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Pedersen EP, Elberling B, Michelsen A. Foraging deeply: Depth-specific plant nitrogen uptake in response to climate-induced N-release and permafrost thaw in the High Arctic. GLOBAL CHANGE BIOLOGY 2020; 26:6523-6536. [PMID: 32777164 DOI: 10.1111/gcb.15306] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Warming in the Arctic accelerates top-soil decomposition and deep-soil permafrost thaw. This may lead to an increase in plant-available nutrients throughout the active layer soil and near the permafrost thaw front. For nitrogen (N) limited high arctic plants, increased N availability may enhance growth and alter community composition, importantly affecting the ecosystem carbon balance. However, the extent to which plants can take advantage of this newly available N may be constrained by the following three factors: vertical distribution of N within the soil profile, timing of N-release, and competition with other plants and microorganisms. Therefore, we investigated species- and depth-specific plant N uptake in a high arctic tundra, northeastern Greenland. Using stable isotopic labelling (15 N-NH4 + ), we simulated autumn N-release at three depths within the active layer: top (10 cm), mid (45 cm) and deep-soil near the permafrost thaw front (90 cm). We measured plant species-specific N uptake immediately after N-release (autumn) and after 1 year, and assessed depth-specific microbial N uptake and resource partitioning between above- and below-ground plant parts, microorganisms and soil. We found that high arctic plants actively foraged for N past the peak growing season, notably the graminoid Kobresia myosuroides. While most plant species (Carex rupestris, Dryas octopetala, K. myosuroides) preferred top-soil N, the shrub Salix arctica also effectively acquired N from deeper soil layers. All plants were able to obtain N from the permafrost thaw front, both in autumn and during the following growing season, demonstrating the importance of permafrost-released N as a new N source for arctic plants. Finally, microbial N uptake markedly declined with depth, hence, plant access to deep-soil N pools is a competitive strength. In conclusion, plant species-specific competitive advantages with respect to both time- and depth-specific N-release may dictate short- and long-term plant community changes in the Arctic and consequently, larger-scale climate feedbacks.
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Affiliation(s)
- Emily P Pedersen
- Department of Biology, Terrestrial Ecology, University of Copenhagen, Copenhagen, Denmark
- Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Bo Elberling
- Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
| | - Anders Michelsen
- Department of Biology, Terrestrial Ecology, University of Copenhagen, Copenhagen, Denmark
- Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Copenhagen, Denmark
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37
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Olid C, Klaminder J, Monteux S, Johansson M, Dorrepaal E. Decade of experimental permafrost thaw reduces turnover of young carbon and increases losses of old carbon, without affecting the net carbon balance. GLOBAL CHANGE BIOLOGY 2020; 26:5886-5898. [PMID: 32681580 DOI: 10.1111/gcb.15283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
Thicker snowpacks and their insulation effects cause winter-warming and invoke thaw of permafrost ecosystems. Temperature-dependent decomposition of previously frozen carbon (C) is currently considered one of the strongest feedbacks between the Arctic and the climate system, but the direction and magnitude of the net C balance remains uncertain. This is because winter effects are rarely integrated with C fluxes during the snow-free season and because predicting the net C balance from both surface processes and thawing deep layers remains challenging. In this study, we quantified changes in the long-term net C balance (net ecosystem production) in a subarctic peat plateau subjected to 10 years of experimental winter-warming. By combining 210 Pb and 14 Cdating of peat cores with peat growth models, we investigated thawing effects on year-round primary production and C losses through respiration and leaching from both shallow and deep peat layers. Winter-warming and permafrost thaw had no effect on the net C balance, but strongly affected gross C fluxes. Carbon losses through decomposition from the upper peat were reduced as thawing of permafrost induced surface subsidence and subsequent waterlogging. However, primary production was also reduced likely due to a strong decline in bryophytes cover while losses from the old C pool almost tripled, caused by the deepened active layer. Our findings highlight the need to estimate long-term responses of whole-year production and decomposition processes to thawing, both in shallow and deep soil layers, as they may contrast and lead to unexpected net effects on permafrost C storage.
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Affiliation(s)
- Carolina Olid
- Climate Impacts Research Centre (CIRC), Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Jonatan Klaminder
- Climate Impacts Research Centre (CIRC), Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
| | - Sylvain Monteux
- Climate Impacts Research Centre (CIRC), Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
- Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Margareta Johansson
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
- Royal Swedish Academy of Science, Stockholm, Sweden
| | - Ellen Dorrepaal
- Climate Impacts Research Centre (CIRC), Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
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Mao C, Kou D, Chen L, Qin S, Zhang D, Peng Y, Yang Y. Permafrost nitrogen status and its determinants on the Tibetan Plateau. GLOBAL CHANGE BIOLOGY 2020; 26:5290-5302. [PMID: 32506764 DOI: 10.1111/gcb.15205] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 05/27/2020] [Accepted: 05/29/2020] [Indexed: 06/11/2023]
Abstract
It had been suggested that permafrost thaw could promote frozen nitrogen (N) release and modify microbial N transformation rates, which might alter soil N availability and then regulate ecosystem functions. However, the current understanding of this issue is confined to limited observations in the Arctic permafrost region, without any systematic measurements in other permafrost regions. Based on a large-scale field investigation along a 1,000 km transect and a laboratory incubation experiment with a 15 N pool dilution approach, this study provides the comprehensive evaluation of the permafrost N status, including the available N content and related N transformation rates, across the Tibetan alpine permafrost region. In contrast to the prevailing view, our results showed that the Tibetan alpine permafrost had lower available N content and net N mineralization rate than the active layer. Moreover, the permafrost had lower gross rates of N mineralization, microbial immobilization and nitrification than the active layer. Our results also revealed that the dominant drivers of the gross N mineralization and microbial immobilization rates differed between the permafrost and the active layer, with these rates being determined by microbial properties in the permafrost while regulated by soil moisture in the active layer. In contrast, soil gross nitrification rate was consistently modulated by the soil NH 4 + content in both the permafrost and the active layer. Overall, patterns and drivers of permafrost N pools and transformation rates observed in this study offer new insights into the potential N release upon permafrost thaw and provide important clues for Earth system models to better predict permafrost biogeochemical cycles under a warming climate.
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Affiliation(s)
- Chao Mao
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dan Kou
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Biogeochemistry Research Group, Department of Biological and Environmental Sciences, University of Eastern Finland, Kuopio, Finland
| | - Leiyi Chen
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Shuqi Qin
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Dianye Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yunfeng Peng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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39
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Higgens RF, Pries CH, Virginia RA. Trade-offs Between Wood and Leaf Production in Arctic Shrubs Along a Temperature and Moisture Gradient in West Greenland. Ecosystems 2020. [DOI: 10.1007/s10021-020-00541-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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40
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Herndon E, Kinsman-Costello L, Di Domenico N, Duroe K, Barczok M, Smith C, Wullschleger SD. Iron and iron-bound phosphate accumulate in surface soils of ice-wedge polygons in arctic tundra. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:1475-1490. [PMID: 32475995 DOI: 10.1039/d0em00142b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Phosphorus (P) is a limiting or co-limiting nutrient to plants and microorganisms in diverse ecosystems that include the arctic tundra. Certain soil minerals can adsorb or co-precipitate with phosphate, and this mineral-bound P provides a potentially large P reservoir in soils. Iron (Fe) oxyhydroxides have a high capacity to adsorb phosphate; however, the ability of Fe oxyhydroxides to adsorb phosphate and limit P bioavailability in organic tundra soils is not known. Here, we examined the depth distribution of soil Fe and P species in the active layer (<30 cm) of low-centered and high-centered ice-wedge polygons at the Barrow Environmental Observatory on the Alaska North Slope. Soil reservoirs of Fe and P in bulk horizons and in narrower depth increments were characterized using sequential chemical extractions and synchrotron-based X-ray absorption spectroscopy (XAS). Organic horizons across all polygon features (e.g., trough, ridge, and center) were enriched in extractable Fe and P relative to mineral horizons. Soil Fe was dominated by organic-bound Fe and short-range ordered Fe oxyhydroxides, while soil P was primarily associated with oxides and organic matter in organic horizons but apatite and/or calcareous minerals in mineral horizons. Iron oxyhydroxides and Fe-bound inorganic P (Pi) were most enriched at the soil surface and decreased gradually with depth, and Fe-bound Pi was >4× greater than water-soluble Pi. These results demonstrate that Fe-bound Pi is a large and ecologically important reservoir of phosphate. We contend that Fe oxyhydroxides and other minerals may regulate Pi solubility under fluctuating redox conditions in organic surface soils on the arctic tundra.
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Affiliation(s)
- Elizabeth Herndon
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA. and Department of Geology, Kent State University, Kent, OH, USA
| | | | | | - Kiersten Duroe
- Department of Geology, Kent State University, Kent, OH, USA
| | | | - Chelsea Smith
- Department of Biological Sciences, Kent State University, Kent, OH, USA
| | - Stan D Wullschleger
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
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Kou D, Yang G, Li F, Feng X, Zhang D, Mao C, Zhang Q, Peng Y, Ji C, Zhu Q, Fang Y, Liu X, Xu-Ri, Li S, Deng J, Zheng X, Fang J, Yang Y. Progressive nitrogen limitation across the Tibetan alpine permafrost region. Nat Commun 2020; 11:3331. [PMID: 32620773 PMCID: PMC7335038 DOI: 10.1038/s41467-020-17169-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 06/15/2020] [Indexed: 11/13/2022] Open
Abstract
The ecosystem carbon (C) balance in permafrost regions, which has a global significance in understanding the terrestrial C-climate feedback, is significantly regulated by nitrogen (N) dynamics. However, our knowledge on temporal changes in vegetation N limitation (i.e., the supply of N relative to plant N demand) in permafrost ecosystems is still limited. Based on the combination of isotopic observations derived from a re-sampling campaign along a ~3000 km transect and simulations obtained from a process-based biogeochemical model, here we detect changes in ecosystem N cycle across the Tibetan alpine permafrost region over the past decade. We find that vegetation N limitation becomes stronger despite the increased available N production. The enhanced N limitation on vegetation growth is driven by the joint effects of elevated plant N demand and gaseous N loss. These findings suggest that N would constrain the future trajectory of ecosystem C cycle in this alpine permafrost region.
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Affiliation(s)
- Dan Kou
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
- Biogeochemistry Research Group, Department of Biological and Environmental Sciences, University of Eastern Finland, Kuopio, 70210, Finland
- Earth, Atmospheric and Planetary Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Guibiao Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Fei Li
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xuehui Feng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Dianye Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chao Mao
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiwen Zhang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunfeng Peng
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Chengjun Ji
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, China
| | - Qiuan Zhu
- College of Hydrology and Water Resources, Hohai University, Nanjing, 210098, China
| | - Yunting Fang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Xueyan Liu
- School of Earth System Science, Tianjin University, Tianjin, 300072, China
| | - Xu-Ri
- Key Laboratory of Alpine Ecology and Biodiversity, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Siqi Li
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Jia Deng
- Earth Systems Research Centre, Institute for the Study of Earth, Oceans and Space, University of New Hampshire, Durham, NH, 03824, USA
| | - Xunhua Zheng
- University of Chinese Academy of Sciences, Beijing, 100049, China
- State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
| | - Jingyun Fang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, 100871, China
| | - Yuanhe Yang
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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42
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Luo Y, Schuur EAG. Model parameterization to represent processes at unresolved scales and changing properties of evolving systems. GLOBAL CHANGE BIOLOGY 2020; 26:1109-1117. [PMID: 31782216 DOI: 10.1111/gcb.14939] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 11/21/2019] [Accepted: 11/22/2019] [Indexed: 06/10/2023]
Abstract
Modeling has become an indispensable tool for scientific research. However, models generate great uncertainty when they are used to predict or forecast ecosystem responses to global change. This uncertainty is partly due to parameterization, which is an essential procedure for model specification via defining parameter values for a model. The classic doctrine of parameterization is that a parameter is constant. However, it is commonly known from modeling practice that a model that is well calibrated for its parameters at one site may not simulate well at another site unless its parameters are tuned again. This common practice implies that parameter values have to vary with sites. Indeed, parameter values that are estimated using a statistically rigorous approach, that is, data assimilation, vary with time, space, and treatments in global change experiments. This paper illustrates that varying parameters is to account for both processes at unresolved scales and changing properties of evolving systems. A model, no matter how complex it is, could not represent all the processes of one system at resolved scales. Interactions of processes at unresolved scales with those at resolved scales should be reflected in model parameters. Meanwhile, it is pervasively observed that properties of ecosystems change over time, space, and environmental conditions. Parameters, which represent properties of a system under study, should change as well. Tuning has been practiced for many decades to change parameter values. Yet this activity, unfortunately, did not contribute to our knowledge on model parameterization at all. Data assimilation makes it possible to rigorously estimate parameter values and, consequently, offers an approach to understand which, how, how much, and why parameters vary. To fully understand those issues, extensive research is required. Nonetheless, it is clear that changes in parameter values lead to different model predictions even if the model structure is the same.
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Affiliation(s)
- Yiqi Luo
- Department of Biological Sciences, Center for Ecosystem Sciences and Society, Northern Arizona University, Flagstaff, AZ, USA
| | - Edward A G Schuur
- Department of Biological Sciences, Center for Ecosystem Sciences and Society, Northern Arizona University, Flagstaff, AZ, USA
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43
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Liu Z, Kimball JS, Parazoo NC, Ballantyne AP, Wang WJ, Madani N, Pan CG, Watts JD, Reichle RH, Sonnentag O, Marsh P, Hurkuck M, Helbig M, Quinton WL, Zona D, Ueyama M, Kobayashi H, Euskirchen ES. Increased high-latitude photosynthetic carbon gain offset by respiration carbon loss during an anomalous warm winter to spring transition. GLOBAL CHANGE BIOLOGY 2020; 26:682-696. [PMID: 31596019 DOI: 10.1111/gcb.14863] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 07/21/2019] [Indexed: 06/10/2023]
Abstract
Arctic and boreal ecosystems play an important role in the global carbon (C) budget, and whether they act as a future net C sink or source depends on climate and environmental change. Here, we used complementary in situ measurements, model simulations, and satellite observations to investigate the net carbon dioxide (CO2 ) seasonal cycle and its climatic and environmental controls across Alaska and northwestern Canada during the anomalously warm winter to spring conditions of 2015 and 2016 (relative to 2010-2014). In the warm spring, we found that photosynthesis was enhanced more than respiration, leading to greater CO2 uptake. However, photosynthetic enhancement from spring warming was partially offset by greater ecosystem respiration during the preceding anomalously warm winter, resulting in nearly neutral effects on the annual net CO2 balance. Eddy covariance CO2 flux measurements showed that air temperature has a primary influence on net CO2 exchange in winter and spring, while soil moisture has a primary control on net CO2 exchange in the fall. The net CO2 exchange was generally more moisture limited in the boreal region than in the Arctic tundra. Our analysis indicates complex seasonal interactions of underlying C cycle processes in response to changing climate and hydrology that may not manifest in changes in net annual CO2 exchange. Therefore, a better understanding of the seasonal response of C cycle processes may provide important insights for predicting future carbon-climate feedbacks and their consequences on atmospheric CO2 dynamics in the northern high latitudes.
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Affiliation(s)
- Zhihua Liu
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, China
- Numerical Terradynamic Simulation Group, WA Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - John S Kimball
- Numerical Terradynamic Simulation Group, WA Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
- Department of Ecosystem and Conservation Sciences, WA Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - Nicholas C Parazoo
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Ashley P Ballantyne
- Department of Ecosystem and Conservation Sciences, WA Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | - Wen J Wang
- Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, China
| | - Nima Madani
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - Caleb G Pan
- Numerical Terradynamic Simulation Group, WA Franke College of Forestry and Conservation, University of Montana, Missoula, MT, USA
| | | | | | - Oliver Sonnentag
- Département de géographie and Centre d'études nordiques, Université de Montréal, Montreal, QC, Canada
| | - Philip Marsh
- Cold Regions Research Centre, Wilfrid Laurier University, Waterloo, ON, Canada
| | - Miriam Hurkuck
- Département de géographie and Centre d'études nordiques, Université de Montréal, Montreal, QC, Canada
| | - Manuel Helbig
- School of Geography and Earth Sciences, McMaster University, Hamilton, ON, Canada
| | - William L Quinton
- Cold Regions Research Centre, Wilfrid Laurier University, Waterloo, ON, Canada
| | - Donatella Zona
- Global Change Research Group, Department of Biology, San Diego State University, San Diego, CA, USA
| | - Masahito Ueyama
- Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Sakai, Japan
| | - Hideki Kobayashi
- Institute of Arctic Climate and Environment Research, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan
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44
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Feng J, Wang C, Lei J, Yang Y, Yan Q, Zhou X, Tao X, Ning D, Yuan MM, Qin Y, Shi ZJ, Guo X, He Z, Van Nostrand JD, Wu L, Bracho-Garillo RG, Penton CR, Cole JR, Konstantinidis KT, Luo Y, Schuur EAG, Tiedje JM, Zhou J. Warming-induced permafrost thaw exacerbates tundra soil carbon decomposition mediated by microbial community. MICROBIOME 2020; 8:3. [PMID: 31952472 PMCID: PMC6969446 DOI: 10.1186/s40168-019-0778-3] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/23/2019] [Indexed: 05/27/2023]
Abstract
BACKGROUND It is well-known that global warming has effects on high-latitude tundra underlain with permafrost. This leads to a severe concern that decomposition of soil organic carbon (SOC) previously stored in this region, which accounts for about 50% of the world's SOC storage, will cause positive feedback that accelerates climate warming. We have previously shown that short-term warming (1.5 years) stimulates rapid, microbe-mediated decomposition of tundra soil carbon without affecting the composition of the soil microbial community (based on the depth of 42684 sequence reads of 16S rRNA gene amplicons per 3 g of soil sample). RESULTS We show that longer-term (5 years) experimental winter warming at the same site altered microbial communities (p < 0.040). Thaw depth correlated the strongest with community assembly and interaction networks, implying that warming-accelerated tundra thaw fundamentally restructured the microbial communities. Both carbon decomposition and methanogenesis genes increased in relative abundance under warming, and their functional structures strongly correlated (R2 > 0.725, p < 0.001) with ecosystem respiration or CH4 flux. CONCLUSIONS Our results demonstrate that microbial responses associated with carbon cycling could lead to positive feedbacks that accelerate SOC decomposition in tundra regions, which is alarming because SOC loss is unlikely to subside owing to changes in microbial community composition. Video Abstract.
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Affiliation(s)
- Jiajie Feng
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Cong Wang
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Jiesi Lei
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Yunfeng Yang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
| | - Qingyun Yan
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Xishu Zhou
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
- School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China
| | - Xuanyu Tao
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Daliang Ning
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Mengting M Yuan
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Yujia Qin
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Zhou J Shi
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Xue Guo
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China
| | - Zhili He
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
- Environmental Microbiomics Research Center, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
- Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, 510006, China
| | - Joy D Van Nostrand
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Liyou Wu
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA
| | - Rosvel G Bracho-Garillo
- School of Forest Resources and Conservation, University of Florida, Gainesville, FL, 32611, USA
| | - C Ryan Penton
- Center for Fundamental and Applied Microbiomics, Arizona State University, Mesa, AZ, 85212, USA
- College of Integrative Sciences and Arts, Faculty of Science and Mathematics, Arizona State University, Mesa, Arizona, 85212, USA
| | - James R Cole
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
| | - Konstantinos T Konstantinidis
- School of Civil and Environmental Engineering, School of Biology, and Center for Bioinformatics and Computational Genomics, Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Yiqi Luo
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - Edward A G Schuur
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, 86011, USA
| | - James M Tiedje
- Center for Microbial Ecology, Michigan State University, East Lansing, MI, 48824, USA
- DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, 48824, USA
| | - Jizhong Zhou
- Institute for Environmental Genomics, Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK, 73019, USA.
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China.
- Earth and Environmental Sciences, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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Blume-Werry G, Milbau A, Teuber LM, Johansson M, Dorrepaal E. Dwelling in the deep - strongly increased root growth and rooting depth enhance plant interactions with thawing permafrost soil. THE NEW PHYTOLOGIST 2019; 223:1328-1339. [PMID: 31074867 DOI: 10.1111/nph.15903] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 04/12/2019] [Indexed: 05/27/2023]
Abstract
Climate-warming-induced permafrost thaw exposes large amounts of carbon and nitrogen in soil at considerable depths, below the seasonally thawing active layer. The extent to which plant roots can reach and interact with these hitherto detached, deep carbon and nitrogen stores remains unknown. We aimed to quantify how permafrost thaw affects root dynamics across soil depths and plant functional types compared with above-ground abundance, and potential consequences for plant-soil interactions. A decade of experimental permafrost thaw strongly increased total root length and growth in the active layer, and deep roots invaded the newly thawed permafrost underneath. Root litter input to soil across all depths was 10 times greater with permafrost thaw. Root growth timing was unaffected by experimental permafrost thaw but peaked later in deeper soil, reflecting the seasonally receding thaw front. Deep-rooting species could sequester 15 N added at the base of the ambient active layer in October, which was after root growth had ceased. Deep soil organic matter that has long been locked up in permafrost is thus no longer detached from plant processes upon thaw. Whether via nutrient uptake, carbon storage, or rhizosphere priming, plant root interactions with thawing permafrost soils may feed back on our climate both positively and negatively.
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Affiliation(s)
- Gesche Blume-Werry
- Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden
- Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, 17487, Greifswald, Germany
| | - Ann Milbau
- Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden
- Research Institute for Nature and Forest INBO, Havenlaan 88, Bus 73, 1000, Brussels, Belgium
| | - Laurenz M Teuber
- Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden
- Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, 17487, Greifswald, Germany
| | - Margareta Johansson
- Department of Physical Geography and Ecosystem Science, Lund University, Solvegatan 12, 223 62, Lund, Sweden
| | - Ellen Dorrepaal
- Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, 981 07, Abisko, Sweden
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Voigt C, Marushchak ME, Mastepanov M, Lamprecht RE, Christensen TR, Dorodnikov M, Jackowicz-Korczyński M, Lindgren A, Lohila A, Nykänen H, Oinonen M, Oksanen T, Palonen V, Treat CC, Martikainen PJ, Biasi C. Ecosystem carbon response of an Arctic peatland to simulated permafrost thaw. GLOBAL CHANGE BIOLOGY 2019; 25:1746-1764. [PMID: 30681758 DOI: 10.1111/gcb.14574] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 01/11/2019] [Indexed: 06/09/2023]
Abstract
Permafrost peatlands are biogeochemical hot spots in the Arctic as they store vast amounts of carbon. Permafrost thaw could release part of these long-term immobile carbon stocks as the greenhouse gases (GHGs) carbon dioxide (CO2 ) and methane (CH4 ) to the atmosphere, but how much, at which time-span and as which gaseous carbon species is still highly uncertain. Here we assess the effect of permafrost thaw on GHG dynamics under different moisture and vegetation scenarios in a permafrost peatland. A novel experimental approach using intact plant-soil systems (mesocosms) allowed us to simulate permafrost thaw under near-natural conditions. We monitored GHG flux dynamics via high-resolution flow-through gas measurements, combined with detailed monitoring of soil GHG concentration dynamics, yielding insights into GHG production and consumption potential of individual soil layers. Thawing the upper 10-15 cm of permafrost under dry conditions increased CO2 emissions to the atmosphere (without vegetation: 0.74 ± 0.49 vs. 0.84 ± 0.60 g CO2 -C m-2 day-1 ; with vegetation: 1.20 ± 0.50 vs. 1.32 ± 0.60 g CO2 -C m-2 day-1 , mean ± SD, pre- and post-thaw, respectively). Radiocarbon dating (14 C) of respired CO2 , supported by an independent curve-fitting approach, showed a clear contribution (9%-27%) of old carbon to this enhanced post-thaw CO2 flux. Elevated concentrations of CO2 , CH4 , and dissolved organic carbon at depth indicated not just pulse emissions during the thawing process, but sustained decomposition and GHG production from thawed permafrost. Oxidation of CH4 in the peat column, however, prevented CH4 release to the atmosphere. Importantly, we show here that, under dry conditions, peatlands strengthen the permafrost-carbon feedback by adding to the atmospheric CO2 burden post-thaw. However, as long as the water table remains low, our results reveal a strong CH4 sink capacity in these types of Arctic ecosystems pre- and post-thaw, with the potential to compensate part of the permafrost CO2 losses over longer timescales.
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Affiliation(s)
- Carolina Voigt
- Department of Geography, University of Montréal, Montréal, Québec, Canada
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Maija E Marushchak
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Mikhail Mastepanov
- Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, Denmark
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
| | - Richard E Lamprecht
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Torben R Christensen
- Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, Denmark
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
| | - Maxim Dorodnikov
- Department of Soil Science of Temperate Ecosystems, Georg-August-University, Göttingen, Germany
| | - Marcin Jackowicz-Korczyński
- Department of Bioscience, Arctic Research Centre, Aarhus University, Roskilde, Denmark
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
| | - Amelie Lindgren
- Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden
- Department of Physical Geography, Stockholm University, Stockholm, Sweden
| | | | - Hannu Nykänen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Markku Oinonen
- Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
| | - Timo Oksanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Vesa Palonen
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Claire C Treat
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Pertti J Martikainen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
| | - Christina Biasi
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio, Finland
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Guo Y, Song C, Tan W, Wang X, Lu Y. Export of dissolved nitrogen in catchments underlain by permafrost in northeast China. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 660:1210-1218. [PMID: 30743916 DOI: 10.1016/j.scitotenv.2018.12.464] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Revised: 12/29/2018] [Accepted: 12/30/2018] [Indexed: 06/09/2023]
Abstract
Eurasian permafrost serves as an important nitrogen source for linked aquatic and oceanic ecosystems. To fill in the data gaps in the southern margin of the Eurasian permafrost, nitrogen dynamics in the two rivers that drain the permafrost in the Great Xing'an Mountains of northeast China were investigated during the 2012-2015 growing seasons. The mean concentration of total dissolved nitrogen (TDN) in the two catchments was 0.63 mg L-1, which is generally higher than other permafrost catchments around the Arctic Ocean. The dissolved organic nitrogen (DON) constituted the majority of TDN, and the mean DON:TDN ratio was as high as 0.84. The seasonal flood patterns broadly influenced the concentrations and annual loads of DON, as well as the dissolved organic carbon (DOC):DON ratios in the two rivers. River discharge was positively related to DON concentration during growing seasons, while the concentrations of dissolved inorganic nitrogen (DIN), namely ammonium and nitrate, demonstrated no relationship with discharge. The estimated annual TDN yield, 190 kg km-2 yr-1 on average, was much higher than in the large Arctic rivers that drain permafrost. This yield accounts for 42.7% of the total atmospheric nitrogen deposition in the study area, which indicates a great potential for dissolved nitrogen export from the permafrost area in the Great Xing'an Mountains.
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Affiliation(s)
- Yuedong Guo
- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
| | - Changchun Song
- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China.
| | - Wenwen Tan
- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
| | - Xianwei Wang
- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
| | - Yongzheng Lu
- Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun 130102, China
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Kwon MJ, Natali SM, Hicks Pries CE, Schuur EAG, Steinhof A, Crummer KG, Zimov N, Zimov SA, Heimann M, Kolle O, Göckede M. Drainage enhances modern soil carbon contribution but reduces old soil carbon contribution to ecosystem respiration in tundra ecosystems. GLOBAL CHANGE BIOLOGY 2019; 25:1315-1325. [PMID: 30681227 DOI: 10.1111/gcb.14578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2018] [Revised: 01/15/2019] [Accepted: 01/17/2019] [Indexed: 05/06/2023]
Abstract
Warming temperatures are likely to accelerate permafrost thaw in the Arctic, potentially leading to the release of old carbon previously stored in deep frozen soil layers. Deeper thaw depths in combination with geomorphological changes due to the loss of ice structures in permafrost, may modify soil water distribution, creating wetter or drier soil conditions. Previous studies revealed higher ecosystem respiration rates under drier conditions, and this study investigated the cause of the increased ecosystem respiration rates using radiocarbon signatures of respired CO2 from two drying manipulation experiments: one in moist and the other in wet tundra. We demonstrate that higher contributions of CO2 from shallow soil layers (0-15 cm; modern soil carbon) drive the increased ecosystem respiration rates, while contributions from deeper soil (below 15 cm from surface and down to the permafrost table; old soil carbon) decreased. These changes can be attributed to more aerobic conditions in shallow soil layers, but also the soil temperature increases in shallow layers but decreases in deep layers, due to the altered thermal properties of organic soils. Decreased abundance of aerenchymatous plant species following drainage in wet tundra reduced old carbon release but increased aboveground plant biomass elevated contributions of autotrophic respiration to ecosystem respiration. The results of this study suggest that drier soils following drainage may accelerate decomposition of modern soil carbon in shallow layers but slow down decomposition of old soil carbon in deep layers, which may offset some of the old soil carbon loss from thawing permafrost.
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Affiliation(s)
- Min Jung Kwon
- Max Planck Institute for Biogeochemistry, Jena, Germany
- Korea Polar Research Institute, Incheon, South Korea
| | | | - Caitlin E Hicks Pries
- Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire
| | - Edward A G Schuur
- Center for Ecosystem Science and Society, and Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona
| | - Axel Steinhof
- Max Planck Institute for Biogeochemistry, Jena, Germany
| | - K Grace Crummer
- Department of Biology, University of Florida, Gainesville, Florida
| | - Nikita Zimov
- North-East Science Station, Pacific Institute for Geography, Far-Eastern Branch of Russian Academy of Science, Chersky, Republic of Sakha (Yakutia), Russia
| | - Sergey A Zimov
- North-East Science Station, Pacific Institute for Geography, Far-Eastern Branch of Russian Academy of Science, Chersky, Republic of Sakha (Yakutia), Russia
| | - Martin Heimann
- Max Planck Institute for Biogeochemistry, Jena, Germany
- Division of Atmospheric Sciences, Department of Physics, Helsinki University, Helsinki, Finland
| | - Olaf Kolle
- Max Planck Institute for Biogeochemistry, Jena, Germany
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Myers‐Smith IH, Grabowski MM, Thomas HJD, Angers‐Blondin S, Daskalova GN, Bjorkman AD, Cunliffe AM, Assmann JJ, Boyle JS, McLeod E, McLeod S, Joe R, Lennie P, Arey D, Gordon RR, Eckert CD. Eighteen years of ecological monitoring reveals multiple lines of evidence for tundra vegetation change. ECOL MONOGR 2019. [DOI: 10.1002/ecm.1351] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Isla H. Myers‐Smith
- School of GeoSciences University of Edinburgh Edinburgh EH9 3FF United Kingdom
| | | | - Haydn J. D. Thomas
- School of GeoSciences University of Edinburgh Edinburgh EH9 3FF United Kingdom
| | | | | | - Anne D. Bjorkman
- School of GeoSciences University of Edinburgh Edinburgh EH9 3FF United Kingdom
- Section for Ecoinformatics & Biodiversity Department of Bioscience Aarhus University DK‐8000 Aarhus Denmark
| | - Andrew M. Cunliffe
- School of GeoSciences University of Edinburgh Edinburgh EH9 3FF United Kingdom
| | - Jakob J. Assmann
- School of GeoSciences University of Edinburgh Edinburgh EH9 3FF United Kingdom
| | - Joseph S. Boyle
- School of GeoSciences University of Edinburgh Edinburgh EH9 3FF United Kingdom
| | - Edward McLeod
- Department of Environment Yukon Parks–Inuvik Office Yukon Territorial Government Inuvik NWT X0E 0T0 Canada
| | - Samuel McLeod
- Department of Environment Yukon Parks–Inuvik Office Yukon Territorial Government Inuvik NWT X0E 0T0 Canada
| | - Ricky Joe
- Department of Environment Yukon Parks–Inuvik Office Yukon Territorial Government Inuvik NWT X0E 0T0 Canada
| | - Paden Lennie
- Department of Environment Yukon Parks–Inuvik Office Yukon Territorial Government Inuvik NWT X0E 0T0 Canada
| | - Deon Arey
- Department of Environment Yukon Parks–Inuvik Office Yukon Territorial Government Inuvik NWT X0E 0T0 Canada
| | - Richard R. Gordon
- Department of Environment Yukon Parks–Inuvik Office Yukon Territorial Government Inuvik NWT X0E 0T0 Canada
| | - Cameron D. Eckert
- Department of Environment Yukon Parks–Whitehorse Office Yukon Territorial Government Whitehorse Yukon Territory Y1A 2C6 Canada
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