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Kilner CL, Carrell AA, Wieczynski DJ, Votzke S, DeWitt K, Yammine A, Shaw J, Pelletier DA, Weston DJ, Gibert JP. Temperature and CO 2 interactively drive shifts in the compositional and functional structure of peatland protist communities. GLOBAL CHANGE BIOLOGY 2024; 30:e17203. [PMID: 38433341 DOI: 10.1111/gcb.17203] [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: 05/17/2023] [Revised: 01/20/2024] [Accepted: 01/26/2024] [Indexed: 03/05/2024]
Abstract
Microbes affect the global carbon cycle that influences climate change and are in turn influenced by environmental change. Here, we use data from a long-term whole-ecosystem warming experiment at a boreal peatland to answer how temperature and CO2 jointly influence communities of abundant, diverse, yet poorly understood, non-fungi microbial Eukaryotes (protists). These microbes influence ecosystem function directly through photosynthesis and respiration, and indirectly, through predation on decomposers (bacteria and fungi). Using a combination of high-throughput fluid imaging and 18S amplicon sequencing, we report large climate-induced, community-wide shifts in the community functional composition of these microbes (size, shape, and metabolism) that could alter overall function in peatlands. Importantly, we demonstrate a taxonomic convergence but a functional divergence in response to warming and elevated CO2 with most environmental responses being contingent on organismal size: warming effects on functional composition are reversed by elevated CO2 and amplified in larger microbes but not smaller ones. These findings show how the interactive effects of warming and rising CO2 levels could alter the structure and function of peatland microbial food webs-a fragile ecosystem that stores upwards of 25% of all terrestrial carbon and is increasingly threatened by human exploitation.
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Affiliation(s)
- Christopher L Kilner
- Department of Biology, Duke University, Durham, North Carolina, USA
- Bird Conservancy of the Rockies, Fort Collins, Colorado, USA
| | - Alyssa A Carrell
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | | | - Samantha Votzke
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Katrina DeWitt
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Andrea Yammine
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Jonathan Shaw
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Dale A Pelletier
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - David J Weston
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA
| | - Jean P Gibert
- Department of Biology, Duke University, Durham, North Carolina, USA
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2
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Euskirchen ES, Edgar CW, Kane ES, Waldrop MP, Neumann RB, Manies KL, Douglas TA, Dieleman C, Jones MC, Turetsky MR. Persistent net release of carbon dioxide and methane from an Alaskan lowland boreal peatland complex. GLOBAL CHANGE BIOLOGY 2024; 30:e17139. [PMID: 38273498 DOI: 10.1111/gcb.17139] [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: 07/13/2023] [Revised: 11/20/2023] [Accepted: 12/18/2023] [Indexed: 01/27/2024]
Abstract
Permafrost degradation in peatlands is altering vegetation and soil properties and impacting net carbon storage. We studied four adjacent sites in Alaska with varied permafrost regimes, including a black spruce forest on a peat plateau with permafrost, two collapse scar bogs of different ages formed following thermokarst, and a rich fen without permafrost. Measurements included year-round eddy covariance estimates of net carbon dioxide (CO2 ), mid-April to October methane (CH4 ) emissions, and environmental variables. From 2011 to 2022, annual rainfall was above the historical average, snow water equivalent increased, and snow-season duration shortened due to later snow return. Seasonally thawed active layer depths also increased. During this period, all ecosystems acted as slight annual sources of CO2 (13-59 g C m-2 year-1 ) and stronger sources of CH4 (11-14 g CH4 m-2 from ~April to October). The interannual variability of net ecosystem exchange was high, approximately ±100 g C m-2 year-1 , or twice what has been previously reported across other boreal sites. Net CO2 release was positively related to increased summer rainfall and winter snow water equivalent and later snow return. Controls over CH4 emissions were related to increased soil moisture and inundation status. The dominant emitter of carbon was the rich fen, which, in addition to being a source of CO2 , was also the largest CH4 emitter. These results suggest that the future carbon-source strength of boreal lowlands in Interior Alaska may be determined by the area occupied by minerotrophic fens, which are expected to become more abundant as permafrost thaw increases hydrologic connectivity. Since our measurements occur within close proximity of each other (≤1 km2 ), this study also has implications for the spatial scale and data used in benchmarking carbon cycle models and emphasizes the necessity of long-term measurements to identify carbon cycle process changes in a warming climate.
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Affiliation(s)
- Eugénie S Euskirchen
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA
- Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - Colin W Edgar
- Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, Alaska, USA
| | - Evan S Kane
- College of Forest Resources and Environmental Science, Michigan Technological University, Houghton, Michigan, USA
- Northern Research Station, USDA Forest Service, Houghton, Michigan, USA
| | - Mark P Waldrop
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Moffett Fields, Mountain View, California, USA
| | - Rebecca B Neumann
- Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington, USA
| | - Kristen L Manies
- U.S. Geological Survey, Geology, Minerals, Energy, and Geophysics Science Center, Moffett Fields, Mountain View, California, USA
| | - Thomas A Douglas
- U.S. Army Cold Regions Research & Engineering Laboratory, Fort Wainwright, Fairbanks, Alaska, USA
| | - Catherine Dieleman
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada
| | - Miriam C Jones
- U.S. Geological Survey, Florence Bascom Geoscience Center, Reston, Virginia, USA
| | - Merritt R Turetsky
- Institute of Arctic and Alpine Research, Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, Colorado, USA
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3
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Wen L, Mason TJ, Ryan S, Ling JE, Saintilan N, Rodriguez J. Monitoring long-term vegetation condition dynamics in persistent semi-arid wetland communities using time series of Landsat data. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 905:167212. [PMID: 37730050 DOI: 10.1016/j.scitotenv.2023.167212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 09/14/2023] [Accepted: 09/17/2023] [Indexed: 09/22/2023]
Abstract
Wetlands in arid and semi-arid regions are characterized by dry- and wet-phase vegetation expression which responds to variable water resources. Monitoring condition trends in these wetlands is challenging because transitions may be rapid and short-lived, and identification of meaningful condition change requires longitudinal study. Remotely-sensed data provide cost effective, multi-decadal information with sufficient temporal and spatial scale to explore wetland condition. In this study, we used a time series of Enhanced Vegetation Index (EVI) derived from 34 years (1988-2021) of Landsat imagery, to investigate the long-term condition dynamics of six broad vegetation groups (communities) in a large floodplain wetland system, the Macquarie Marshes in Australia. These communities were persistently mapped as River Red Gum wetland, Black Box/Coolibah woodland, Lignum shrubland, Semi-permanent wetland, Terrestrial grassland and Terrestrial woodland. We used generalized additive models (GAM) to explore the response of vegetation to seasonality, river flow and climatic conditions. We found that EVI was a useful metric to monitor both wetland condition and response to climatic and hydrological drivers. Wetland communities were particularly responsive to river flow and seasonality, while terrestrial communities were responsive to climate and seasonality. Our results indicate asymptotic condition responses, and therefore evidence of hydrological thresholds, by some wetland communities to river flows. We did not observe a long-term trend of declining condition although an apparent increase in condition variability towards the end of the time series requires continued monitoring. Our remotely-sensed, landscape-scale monitoring approach merits further ground validation. We discuss how it can be used to provide a management tool which continuously assesses short and long-term wetland condition and informs conservation decisions about water management for environmental flows.
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Affiliation(s)
- Li Wen
- Science, Economics and Insights Division, NSW Department of Planning and Environment, Lidcombe, NSW 2141, Australia.
| | - Tanya J Mason
- Science, Economics and Insights Division, NSW Department of Planning and Environment, Lidcombe, NSW 2141, Australia; Centre for Ecosystem Science, UNSW Sydney, Sydney, NSW 2052, Australia
| | - Shawn Ryan
- Science, Economics and Insights Division, NSW Department of Planning and Environment, Lidcombe, NSW 2141, Australia
| | - Joanne E Ling
- Science, Economics and Insights Division, NSW Department of Planning and Environment, Lidcombe, NSW 2141, Australia
| | - Neil Saintilan
- School of Natural Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Jose Rodriguez
- School of Engineering, The University of Newcastle, Callaghan, NSW 2308, Australia
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4
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Ehnvall B, Ågren AM, Nilsson MB, Ratcliffe JL, Noumonvi KD, Peichl M, Lidberg W, Giesler R, Mörth CM, Öquist MG. Catchment characteristics control boreal mire nutrient regime and vegetation patterns over ~5000 years of landscape development. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 895:165132. [PMID: 37379918 DOI: 10.1016/j.scitotenv.2023.165132] [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: 04/18/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 06/30/2023]
Abstract
Vegetation holds the key to many properties that make natural mires unique, such as surface microtopography, high biodiversity values, effective carbon sequestration and regulation of water and nutrient fluxes across the landscape. Despite this, landscape controls behind mire vegetation patterns have previously been poorly described at large spatial scales, which limits the understanding of basic drivers underpinning mire ecosystem services. We studied catchment controls on mire nutrient regimes and vegetation patterns using a geographically constrained natural mire chronosequence along the isostatically rising coastline in Northern Sweden. By comparing mires of different ages, we can partition vegetation patterns caused by long-term mire succession (<5000 years) and present-day vegetation responses to catchment eco-hydrological settings. We used the remote sensing based normalized difference vegetation index (NDVI) to describe mire vegetation and combined peat physicochemical measures with catchment properties to identify the most important factors that determine mire NDVI. We found strong evidence that mire NDVI depends on nutrient inputs from the catchment area or underlying mineral soil, especially concerning phosphorus and potassium concentrations. Steep mire and catchment slopes, dry conditions and large catchment areas relative to mire areas were associated with higher NDVI. We also found long-term successional patterns, with lower NDVI in older mires. Importantly, the NDVI should be used to describe mire vegetation patterns in open mires if the focus is on surface vegetation, since the canopy cover in tree-covered mires completely dominated the NDVI signal. With our study approach, we can quantitatively describe the connection between landscape properties and mire nutrient regime. Our results confirm that mire vegetation responds to the upslope catchment area, but importantly, also suggest that mire and catchment aging can override the role of catchment influence. This effect was clear across mires of all ages, but was strongest in younger mires.
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Affiliation(s)
- Betty Ehnvall
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden.
| | - Anneli M Ågren
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden
| | - Mats B Nilsson
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden
| | - Joshua L Ratcliffe
- Unit for Field-Based Forest Research, Swedish University of Agricultural Sciences, 922 91 Vindeln, Sweden
| | - Koffi Dodji Noumonvi
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden
| | - Matthias Peichl
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden
| | - William Lidberg
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden
| | - Reiner Giesler
- Climate Impacts Research Centre Umeå, Sweden, Department of Ecology and Environmental Sciences, Umeå University, 90736 Umeå, Sweden
| | - Carl-Magnus Mörth
- Department of Geological Sciences, Stockholm University, Svante Arrheniusväg 8, 10691 Stockholm, Sweden
| | - Mats G Öquist
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd 17, 90183 Umeå, Sweden
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5
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Sun J, Gallego-Sala A, Yu Z. Topographic and climatic controls of peatland distribution on the Tibetan Plateau. Sci Rep 2023; 13:14811. [PMID: 37684329 PMCID: PMC10491611 DOI: 10.1038/s41598-023-39699-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Accepted: 07/29/2023] [Indexed: 09/10/2023] Open
Abstract
The Tibetan Plateau (TP) hosts a variety of mountain peatlands that are sensitive to the amplified warming in this region. However, we still lack a basic understanding of environmental and climatic factors controlling peatland distribution in the region. Here we use a bioclimatic envelope model (PeatStash) and environmental analysis that utilise three peatland datasets-(a) the well-studied Zoige peatland complex, (b) a literature-based dataset of TP peatlands sites, and (c) an existing global peatland map (PEATMAP)-to investigate major drivers of peatland distribution in the TP. The Zoige peatland complex is defined by gentle slopes (< 2°), mean annual temperature at 0-2 °C, and soil moisture index > 1.7, much narrower thresholds than those stemming from PEATMAP. Using these narrower thresholds to predict future changes, we found that the Zoige peatland complex will shrink greatly under full-range future warming scenarios (both SSP1-2.6 and SSP5-8.5). Modelling peatland distribution in the entire TP remains challenging because accurate environmental and climate data at high resolution and a reliable peatland distribution map are still lacking. Improved peatland mapping supported by ground-truthing is necessary to understand drivers of peatland distribution, assess carbon storage and other ecosystem services, and predict the TP's peatlands fate under climate change.
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Affiliation(s)
- Jingjing Sun
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains (Ministry of Education), School of Geographical Sciences, Northeast Normal University, Changchun, Jilin, 130024, China
- Geography Department, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, EX4 4QE, UK
| | - Angela Gallego-Sala
- Geography Department, College of Life and Environmental Sciences, University of Exeter, Exeter, Devon, EX4 4QE, UK.
| | - Zicheng Yu
- Key Laboratory of Geographical Processes and Ecological Security in Changbai Mountains (Ministry of Education), School of Geographical Sciences, Northeast Normal University, Changchun, Jilin, 130024, China.
- State Key Laboratory of Black Soils Conservation and Utilization, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Changchun, Jilin, 130102, China.
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6
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Norby RJ, Baxter T, Živković T, Weston DJ. Shading contributes to Sphagnum decline in response to warming. Ecol Evol 2023; 13:e10542. [PMID: 37732286 PMCID: PMC10507575 DOI: 10.1002/ece3.10542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 08/28/2023] [Accepted: 09/06/2023] [Indexed: 09/22/2023] Open
Abstract
Experimental warming of an ombrotrophic bog in northern Minnesota has caused a rapid decline in the productivity and areal cover of Sphagnum mosses, affecting whole-ecosystem carbon balance and biogeochemistry. Direct effects of elevated temperature and the attendant drying are most likely the primary cause of the effects on Sphagnum, but there may also be responses to the increased shading from shrubs, which increased with increasing temperature. To evaluate the independent effects of reduction in light availability and deposition of shrub litter on Sphagnum productivity, small plots with shrubs removed were laid out adjacent to the warming experiment on hummocks and hollows in three blocks and with five levels of shading. Four plots were covered with neutral density shade cloth to simulate shading from shrubs of 30%-90% reduction in light; one plot was left open. Growth of Sphagnum angustifolium/fallax and S. divinum declined linearly with increasing shade in hollows, but there was no response to shade on hummocks, where higher irradiance in the open plots may have been inhibitory. Shading caused etiolation of Sphagnum-they were thin and spindly under the deepest shade. A dense mat of shrub litter, corresponding to the amount of shrub litter produced in response to warming, did not inhibit Sphagnum growth or cause increases in potentially toxic base cations. CO2 exchange and chlorophyll-a fluorescence of S. angustifolium/fallax from the 30% and 90% shade cloth plots were measured in the laboratory. Light response curves indicate that maximal light saturated photosynthesis was 42% greater for S. angustifolium/fallax grown under 30% shade cloth relative to plants grown under 90% shade cloth. The response of Sphagnum growth in response to increasing shade is consistent with the hypothesis that increased shade resulting from shrub expansion in response to experimental warming contributed to reduced Sphagnum growth.
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Affiliation(s)
- Richard J Norby
- Environmental Sciences Division Oak Ridge National Laboratory Oak Ridge Tennessee USA
- Department of Ecology and Evolutionary Biology University of Tennessee Knoxville Tennessee USA
| | - Taylor Baxter
- Department of Ecology and Evolutionary Biology University of Tennessee Knoxville Tennessee USA
| | - Tatjana Živković
- Department of Biology Dalhousie University Halifax Nova Scotia Canada
- Biological Sciences Division Oak Ridge National Laboratory Oak Ridge Tennessee USA
| | - David J Weston
- Biological Sciences Division Oak Ridge National Laboratory Oak Ridge Tennessee USA
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7
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Hamilton VA, Lee SS, Rober AR, Furey PC, Manoylov KM, Wyatt KH. A Voucher Flora of Diatoms from Fens in the Tanana River Floodplain, Alaska. WATER 2023; 15:1-52. [PMID: 38152466 PMCID: PMC10750759 DOI: 10.3390/w15152803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2023]
Abstract
Climate change and human activities may alter the structure and function of boreal peatlands by warming waters and changing their hydrology. Diatoms can be used to assess or track these changes. However, effective biomonitoring requires consistent, reliable identification. To address this need, this study developed a diatom voucher flora of species found across a boreal fen gradient (e.g., vegetation) in interior Alaskan peatlands. Composite diatom samples were collected bi-weekly from three peatland complexes over the 2017 summer. The morphological range of each taxon was imaged. The fens contained 184 taxa across 38 genera. Eunotia (45), Gomphonema (23), and Pinnularia (20) commonly occurred in each peatland. Tabellaria was common in the rich and moderate fen but sparse in the poor fen. Eunotia showed the opposite trend. Approximately 11% of species are potentially novel and 25% percent matched those at risk or declining in status on the diatom Red List (developed in Germany), highlighting the conservation value of boreal wetlands. This voucher flora expands knowledge of regional diatom biodiversity and provides updated, verifiable taxonomic information for inland Alaskan diatoms, building on Foged's 1981 treatment. This flora strengthens the potential to effectively track changes in boreal waterways sensitive to climate change and anthropogenic stressors.
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Affiliation(s)
| | - Sylvia S. Lee
- Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC 20460, USA
| | - Allison R. Rober
- Department of Biology, Ball State University, Muncie, IN 47306, USA
| | - Paula C. Furey
- Department of Biology, St. Catherine University, St. Paul, MN 55105, USA
| | - Kalina M. Manoylov
- Department of Biological & Environmental Sciences, Georgia College & State University, Milledgeville, GA 31061, USA
| | - Kevin H. Wyatt
- Department of Biology, Ball State University, Muncie, IN 47306, USA
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8
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Salko S, Juola J, Burdun I, Vasander H, Rautiainen M. Intra- and interspecific variation in spectral properties of dominant Sphagnum moss species in boreal peatlands. Ecol Evol 2023; 13:e10197. [PMID: 37325720 PMCID: PMC10261972 DOI: 10.1002/ece3.10197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 05/12/2023] [Accepted: 05/30/2023] [Indexed: 06/17/2023] Open
Abstract
Boreal peatlands store ~25 % of global soil organic carbon and host many endangered species; however, they face degradation due to climate change and anthropogenic drainage. In boreal peatlands, vegetation indicates ecohydrological conditions of the ecosystem. Applying remote sensing would enable spatially and temporally continuous monitoring of peatland vegetation. New multi- and hyperspectral satellite data offer promising approaches for understanding the spectral properties of peatland vegetation at high temporal and spectral resolutions. However, using spectral satellite data to their fullest potential requires detailed spectral analyses of dominant species in peatlands. A dominant feature of peatland vegetation is the genus Sphagnum mosses. We investigated how the reflectance spectra of common boreal Sphagnum mosses, collected from waterlogged natural conditions after snowmelt, change when the mosses are desiccated. We conducted a laboratory experiment where the reflectance spectra (350-2500 nm) and the mass of 90 moss samples (representing nine species) were measured repetitively. Furthermore, we examined (i) their inter- and intraspecific spectral differences and (ii) whether the species or their respective habitats could be identified based on their spectral signatures in varying states of drying. Our findings show that the most informative spectral regions to retrieve information about the Sphagnum species and their state of desiccation are in the shortwave infrared region. Furthermore, the visible and near-infrared spectral regions contain less information on species and moisture content. Our results also indicate that hyperspectral data can, to a limited extent, be used to separate mosses belonging to meso- and ombrotrophic habitats. Overall, this study demonstrates the importance of including data especially from the shortwave infrared region (1100-2500 nm) in remote sensing applications of boreal peatlands. The spectral library of Sphagnum mosses collected in this study is available as open data and can be used to develop new methods for remote monitoring of boreal peatlands.
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Affiliation(s)
| | - Jussi Juola
- School of EngineeringAalto UniversityEspooFinland
| | | | - Harri Vasander
- Department of Forest SciencesUniversity of HelsinkiHelsinkiFinland
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Li C, Zhang R, Li T, Guo H, Guo R. Dynamic Changes and Influencing Factors of Vegetation in the "Green Heart" Zone of the Chang-Zhu-Tan Urban Agglomeration during the Past 21 Years. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:4517. [PMID: 36901526 PMCID: PMC10001680 DOI: 10.3390/ijerph20054517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2022] [Revised: 02/05/2023] [Accepted: 02/27/2023] [Indexed: 06/18/2023]
Abstract
As a policy, protected green space in the rapidly developing the Chang-Zhu-Tan Urban Agglomeration is of great practical significance to study the vegetation changes and influencing factors in the Green Heart area. In this paper, data processing, grading and area statistics were carried out for the maximum value of normalized differential vegetation index (NDVI) from 2000 to 2020. Combined with Theil-Sen median trend analysis and Mann-Kendall, the change trend of long-time series NDVI was studied, and investigation of NDVI influencing factors, processes and mechanisms using geographical detectors. The results showed that: (1) The spatial distribution characteristics of NDVI in the study area were high in the middle and inlaid transition between adjacent grades. Except for the low grades, the distribution of NDVI in other grades was relatively scattered, and the overall trend of NDVI change was rising. (2) Population density was the main factor affecting NDVI changes, with an explanatory power of up to 40%, followed by elevation, precipitation and minimum temperature. (3) The influence of influencing factors on the change of NDVI was not the result of independent action of a single factor, but the result of the interaction between human factors and natural factors, and the factor combinations with greater interaction had significant differences in the spatial distribution of NDVI.
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Affiliation(s)
- Chaokui Li
- Hunan Provincial Key Laboratory of Information Engineering for Surveying, Hunan University of Science and Technology, Xiangtan 411201, China
- National and Local Joint Engineering Laboratory of Geospatial Information Technology, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Rui Zhang
- Hunan Provincial Key Laboratory of Information Engineering for Surveying, Hunan University of Science and Technology, Xiangtan 411201, China
- National and Local Joint Engineering Laboratory of Geospatial Information Technology, Hunan University of Science and Technology, Xiangtan 411201, China
- College of Earth Science and Spatial Information Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Ting Li
- Hunan Provincial Key Laboratory of Information Engineering for Surveying, Hunan University of Science and Technology, Xiangtan 411201, China
- National and Local Joint Engineering Laboratory of Geospatial Information Technology, Hunan University of Science and Technology, Xiangtan 411201, China
- College of Architecture and Artistic Design, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Haibin Guo
- Hunan Provincial Key Laboratory of Information Engineering for Surveying, Hunan University of Science and Technology, Xiangtan 411201, China
- National and Local Joint Engineering Laboratory of Geospatial Information Technology, Hunan University of Science and Technology, Xiangtan 411201, China
- College of Earth Science and Spatial Information Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
| | - Ruirong Guo
- Hunan Provincial Key Laboratory of Information Engineering for Surveying, Hunan University of Science and Technology, Xiangtan 411201, China
- National and Local Joint Engineering Laboratory of Geospatial Information Technology, Hunan University of Science and Technology, Xiangtan 411201, China
- College of Earth Science and Spatial Information Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
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10
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Structuring Life After Death: Plant Leachates Promote CO2 Uptake by Regulating Microbial Biofilm Interactions in a Northern Peatland Ecosystem. Ecosystems 2023. [DOI: 10.1007/s10021-023-00820-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
AbstractShifts in plant functional groups associated with climate change have the potential to influence peatland carbon storage by altering the amount and composition of organic matter available to aquatic microbial biofilms. The goal of this study was to evaluate the potential for plant subsidies to regulate ecosystem carbon flux (CO2) by governing the relative proportion of primary producers (microalgae) and heterotrophic decomposers (heterotrophic bacteria) during aquatic biofilm development in an Alaskan fen. We evaluated biofilm composition and CO2 flux inside mesocosms with and without nutrients (both nitrogen and phosphorus), organic carbon (glucose), and leachates from common peatland plants (moss, sedge, shrub, horsetail). Experimental mesocosms were exposed to either natural sunlight or placed under a dark canopy to evaluate the response of decomposers to nutrients and carbon subsidies with and without algae, respectively. Algae were limited by inorganic nutrients and heterotrophic bacteria were limited by organic carbon. The quality of organic matter varied widely among plants and leachate nutrient content, more so than carbon quality, influenced biofilm composition. By alleviating nutrient limitation of algae, plant leachates shifted the biofilm community toward autotrophy in the light-transparent treatments, resulting in a significant reduction in CO2 emissions compared to the control. Without the counterbalance from algal photosynthesis, a heterotrophic biofilm significantly enhanced CO2 emissions in the presence of plant leachates in the dark. These results show that plants not only promote carbon uptake directly through photosynthesis, but also indirectly through a surrogate, the phototrophic microbes.
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11
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Kwon MJ, Ballantyne A, Ciais P, Qiu C, Salmon E, Raoult N, Guenet B, Göckede M, Euskirchen ES, Nykänen H, Schuur EAG, Turetsky MR, Dieleman CM, Kane ES, Zona D. Lowering water table reduces carbon sink strength and carbon stocks in northern peatlands. GLOBAL CHANGE BIOLOGY 2022; 28:6752-6770. [PMID: 36039832 PMCID: PMC9805217 DOI: 10.1111/gcb.16394] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 07/04/2022] [Indexed: 06/15/2023]
Abstract
Peatlands at high latitudes have accumulated >400 Pg carbon (C) because saturated soil and cold temperatures suppress C decomposition. This substantial amount of C in Arctic and Boreal peatlands is potentially subject to increased decomposition if the water table (WT) decreases due to climate change, including permafrost thaw-related drying. Here, we optimize a version of the Organizing Carbon and Hydrology In Dynamic Ecosystems model (ORCHIDEE-PCH4) using site-specific observations to investigate changes in CO2 and CH4 fluxes as well as C stock responses to an experimentally manipulated decrease of WT at six northern peatlands. The unmanipulated control peatlands, with the WT <20 cm on average (seasonal max up to 45 cm) below the surface, currently act as C sinks in most years (58 ± 34 g C m-2 year-1 ; including 6 ± 7 g C-CH4 m-2 year-1 emission). We found, however, that lowering the WT by 10 cm reduced the CO2 sink by 13 ± 15 g C m-2 year-1 and decreased CH4 emission by 4 ± 4 g CH4 m-2 year-1 , thus accumulating less C over 100 years (0.2 ± 0.2 kg C m-2 ). Yet, the reduced emission of CH4 , which has a larger greenhouse warming potential, resulted in a net decrease in greenhouse gas balance by 310 ± 360 g CO2-eq m-2 year-1 . Peatlands with the initial WT close to the soil surface were more vulnerable to C loss: Non-permafrost peatlands lost >2 kg C m-2 over 100 years when WT is lowered by 50 cm, while permafrost peatlands temporally switched from C sinks to sources. These results highlight that reductions in C storage capacity in response to drying of northern peatlands are offset in part by reduced CH4 emissions, thus slightly reducing the positive carbon climate feedbacks of peatlands under a warmer and drier future climate scenario.
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Affiliation(s)
- Min Jung Kwon
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
- Institute of Soil ScienceUniversity of HamburgHamburgGermany
| | - Ashley Ballantyne
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
- Department of Ecosystem and Conservation ScienceUniversity of MontanaMissoulaMontanaUSA
| | - Philippe Ciais
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
| | - Chunjing Qiu
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
- INRAE, AgroParisTech, Université Paris‐SaclayGif‐sur‐YvetteFrance
| | - Elodie Salmon
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
| | - Nina Raoult
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
| | - Bertrand Guenet
- Laboratoire des Sciences du Climat et de l'EnvironnementCEA‐CNRS‐UVSQGif‐sur‐YvetteFrance
- Laboratoire de Géologie, Ecole Normale SupérieureCNRS, PSL Research UniversityParisFrance
| | - Mathias Göckede
- Systems DepartmentMax Planck Institute for BiogeochemistryJenaGermany
| | | | - Hannu Nykänen
- Department of Environmental and Biological SciencesUniversity of Eastern FinlandKuopioFinland
| | - Edward A. G. Schuur
- College of the Environment, Forestry, and Natural SciencesNorthern Arizona UniversityFlagstaffArizonaUSA
| | - Merritt R. Turetsky
- Institute of Arctic and Alpine ResearchUniversity of ColoradoBoulderColoradoUSA
| | | | - Evan S. Kane
- College of Forest Resources and Environmental ScienceMichigan Technological UniversityHoughtonMichiganUSA
- USDA Forest Service Northern Research StationHoughtonMichiganUSA
| | - Donatella Zona
- Department of Animal and Plant ScienceUniversity of SheffieldSheffieldUK
- Department of BiologySan Diego State UniversitySan DiegoCaliforniaUSA
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12
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Cao R, Lu G, Zhang T, Li Z, Wu X, Sun S. Invertebrate herbivory accelerates shift towards forbs caused by warming in a sedge‐dominated alpine meadow. Ecosphere 2022. [DOI: 10.1002/ecs2.4230] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Rui Cao
- Jiangsu Key Laboratory for Eco‐Agricultural Biotechnology around Hongze Lake, Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection Huaiyin Normal University Huaian China
- Department of Ecology, School of Life Sciences Nanjing University Nanjing China
| | - Guihua Lu
- Jiangsu Key Laboratory for Eco‐Agricultural Biotechnology around Hongze Lake, Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection Huaiyin Normal University Huaian China
| | - Tong Zhang
- Jiangsu Key Laboratory for Eco‐Agricultural Biotechnology around Hongze Lake, Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection Huaiyin Normal University Huaian China
| | - Zhengpeng Li
- Jiangsu Key Laboratory for Eco‐Agricultural Biotechnology around Hongze Lake, Collaborative Innovation Center of Regional Modern Agriculture & Environmental Protection Huaiyin Normal University Huaian China
| | - Xinwei Wu
- Department of Ecology, School of Life Sciences Nanjing University Nanjing China
| | - Shucun Sun
- Department of Ecology, School of Life Sciences Nanjing University Nanjing China
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13
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Antala M, Juszczak R, van der Tol C, Rastogi A. Impact of climate change-induced alterations in peatland vegetation phenology and composition on carbon balance. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 827:154294. [PMID: 35247401 DOI: 10.1016/j.scitotenv.2022.154294] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/03/2022] [Accepted: 02/28/2022] [Indexed: 06/14/2023]
Abstract
Global climate is changing faster than humankind has ever experienced. Model-based predictions of future climate are becoming more complex and precise, but they still lack crucial information about the reaction of some important ecosystems, such as peatlands. Peatlands belong to one of the largest carbon stores on the Earth. They are mostly distributed in high latitudes, where the temperature rises faster than in the other parts of the planet. Warmer climate and changes in precipitation patterns cause changes in the composition and phenology of peatland vegetation. Peat mosses are becoming less abundant, vascular plants cover is increasing, and the vegetation season and phenophases of vascular plants start sooner. The alterations in vegetation cause changes in the carbon assimilation and release of greenhouse gases. Therefore, this article reviews the impact of climate change-induced alterations in peatland vegetation phenology and composition on future climate and the uncertainties that need to be addressed for more accurate climate prediction.
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Affiliation(s)
- Michal Antala
- Laboratory of Bioclimatology, Department of Ecology and Environmental Protection, Faculty of Environmental Engineering and Mechanical Engineering, Poznan University of Life Sciences, Piątkowska 94, 60-649 Poznań, Poland
| | - Radoslaw Juszczak
- Laboratory of Bioclimatology, Department of Ecology and Environmental Protection, Faculty of Environmental Engineering and Mechanical Engineering, Poznan University of Life Sciences, Piątkowska 94, 60-649 Poznań, Poland
| | - Christiaan van der Tol
- Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, 7500 AE Enschede, the Netherlands
| | - Anshu Rastogi
- Laboratory of Bioclimatology, Department of Ecology and Environmental Protection, Faculty of Environmental Engineering and Mechanical Engineering, Poznan University of Life Sciences, Piątkowska 94, 60-649 Poznań, Poland; Faculty of Geo-Information Science and Earth Observation (ITC), University of Twente, 7500 AE Enschede, the Netherlands.
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14
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Wang Y, Xu S, Li B, Chen W, Li Y, He X, Wang N. Responses of spring leaf phenological and functional traits of two urban tree species to air warming and/or elevated ozone. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 179:158-167. [PMID: 35358866 DOI: 10.1016/j.plaphy.2022.03.015] [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: 02/13/2022] [Revised: 03/07/2022] [Accepted: 03/14/2022] [Indexed: 06/14/2023]
Abstract
Climate warming and surface ozone (O3) pollution are important global environmental issues today. However, the combined impacts of air warming and O3 on phenology and its functional traits of urban trees are still poorly understood. Here, an experiment was performed to explore the variations of the spring phenological and functional traits in leaves of Populus alba 'Berolinensis' and Forsythia suspensa under ambient air (15.8 °C, 35.7 ppb), increased air temperature (IT, ambient air temperature + 2 °C, 17.9 °C), elevated O3 (EO, ambient air O3 concentrations + 40 ppb, 77.4 ppb), and their combined treatments (17.7 °C, 74.5 ppb). Our results showed that: IT advanced the beginning of leaf bud expansion phase of P. alba 'Berolinensis' and F. suspensa for 6 d and 5 d, respectively, increased leaf unfolding rate, leaf area and dry weight, and enhanced photosynthesis and antioxidative enzyme activities. EO delayed the beginning of leaf bud expansion phase of P. alba 'Berolinensis' for 5 d, decreased leaf area and biomass, and inhibited photosynthesis and caused oxidative damage of plant leaves. Compared to EO, the combined treatment advanced the spring phenophase, increased growth and induced the higher level of photosynthetic rate and antioxidative enzymes activities in plant leaves, which indicated that the positive effects of increased temperature (17.7 °C) alleviated the inhibition of growth and photosynthesis induced by ozone. Our findings can provide a theoretical reference for predicting the adaptation of functional traits of the two trees blossomed early under warming and O3 pollution at spring phenological stage.
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Affiliation(s)
- Yijing Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Sheng Xu
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China.
| | - Bo Li
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Wei Chen
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Yan Li
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Xingyuan He
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China; Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China.
| | - Nan Wang
- CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China; University of Chinese Academy of Sciences, Beijing, 100049, China
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15
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Kuemmerlen M, Moorkens EA, Piggott JJ. Assessing remote sensing as a tool to monitor hydrological stress in Irish catchments with Freshwater Pearl Mussel populations. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150807. [PMID: 34626624 DOI: 10.1016/j.scitotenv.2021.150807] [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: 07/06/2021] [Revised: 09/22/2021] [Accepted: 10/01/2021] [Indexed: 06/13/2023]
Abstract
The West Coast of Ireland hosts many of the few populations of Freshwater Peal Mussels (FPM) left in Europe. The decline of this keystone species is strongly related to deteriorating hydrological conditions, specifically to the threat of low flows during dry summers. Populations still capable of reproducing require a minimum discharge and flow velocity to support juvenile mussels, or else stress builds up and an entire generation may be lost. Monitoring environmental and hydrological conditions in small and remote FPM catchments is difficult due to the lack of infrastructure. Indices derived from remote sensing imagery can be used to assess hydrological variables at the catchment scale. Here, five indices are tested as possible surrogates for soil moisture and evapotranspiration, based on two relevant land-cover types: open peat habitats (OPH) and forestry. Selected indices are then assessed in their ability to reproduce seasonal patterns and in their response to a severe drought event. The moisture stress index (MSI) and normalized difference vegetation index (NDVI) were found to be the best surrogates for soil moisture and evapotranspiration respectively. Both indices showed seasonality patterns in the two land-cover types, although the variability of MSI was significantly higher. During the 2018 drought, MSI visibly increased only in OPH, while NDVI rose only for forestry. The results suggest that OPH enhances the long-term hydrological resilience of a catchment by conserving water in the peat substrate, while industrial forestry plantations exacerbate the pressure on water during drier periods. This has consequences for river discharge, freshwater biodiversity and specifically for FPM. Implementing these surrogates have the potential to identify land-use management strategies that reduce and even avert the effects of drought on FPM. Such strategies are increasingly necessary in a climate change context, as recurring summer droughts are expected in most of Europe.
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Affiliation(s)
- Mathias Kuemmerlen
- Trinity Centre for the Environment, School of Natural Sciences, Department of Zoology, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
| | - Evelyn A Moorkens
- Trinity Centre for the Environment, School of Natural Sciences, Department of Zoology, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Jeremy J Piggott
- Trinity Centre for the Environment, School of Natural Sciences, Department of Zoology, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
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16
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Sun B, Jiang M, Han G, Zhang L, Zhou J, Bian C, Du Y, Yan L, Xia J. Experimental warming reduces ecosystem resistance and resilience to severe flooding in a wetland. SCIENCE ADVANCES 2022; 8:eabl9526. [PMID: 35080980 PMCID: PMC8791607 DOI: 10.1126/sciadv.abl9526] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Climate warming and extreme hydrological events are threatening the sustainability of wetlands across the globe. However, whether climate warming will amplify or diminish the impact of extreme flooding on wetland ecosystems is unknown. Here, we show that climate warming significantly reduced wetland resistance and resilience to a severe flooding event via a 6-year warming experiment. We first found that warming rapidly altered plant community structure by increasing the dominance of low-canopy species. Then, we showed that warming reduced the resistance and resilience of vegetation productivity to a 72-cm flooding event. Last, we detected slower postflooding carbon processes, such as gross ecosystem productivity, soil respiration, and soil methane emission, under the warming treatment. Our results demonstrate how severe flooding can destabilize wetland vegetation structure and ecosystem function under climate warming. These findings indicate an enhanced footprint of extreme hydrological events in wetland ecosystems in a warmer climate.
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Affiliation(s)
- Baoyu Sun
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264000, China
| | - Ming Jiang
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
| | - Guangxuan Han
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264000, China
- University of Chinese Academy of Sciences, Beijing 100000, China
| | - Liwen Zhang
- Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264000, China
- University of Chinese Academy of Sciences, Beijing 100000, China
| | - Jian Zhou
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Chenyu Bian
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Ying Du
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Liming Yan
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
| | - Jianyang Xia
- State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200000, China
- Research Center for Global Change and Complex Ecosystems, East China Normal University, Shanghai 200000, China
- Corresponding author.
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17
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AminiTabrizi R, Dontsova K, Graf Grachet N, Tfaily MM. Elevated temperatures drive abiotic and biotic degradation of organic matter in a peat bog under oxic conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 804:150045. [PMID: 34798718 DOI: 10.1016/j.scitotenv.2021.150045] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Revised: 08/26/2021] [Accepted: 08/26/2021] [Indexed: 06/13/2023]
Abstract
Understanding the effects of elevated temperatures on soil organic matter (SOM) decomposition pathways in northern peatlands is central to predicting their fate under future warming. Peatlands role as carbon (C) sink is dependent on both anoxic conditions and low temperatures that limit SOM decomposition. Previous studies have shown that elevated temperatures due to climate change can disrupt peatland's C balance by enhancing SOM decomposition and increasing CO2 emissions. However, little is known about how SOM decomposition pathways change at higher temperatures. Here, we used an integrated research approach to investigate the mechanisms behind enhanced CO2 emissions and SOM decomposition under elevated temperatures of surface peat soil collected from a raised and Sphagnum dominated mid-continental bog (S1 bog) peatland at the Marcel Experimental Forest in Minnesota, USA, incubated under oxic conditions at three different temperatures (4, 21, and 35 °C). Our results indicated that elevated temperatures could destabilize peatland's C pool via a combination of abiotic and biotic processes. In particular, temperature-driven changes in redox conditions can lead to abiotic destabilization of Fe-organic matter (phenol) complexes, previously an underestimated decomposition pathway in peatlands, leading to increased CO2 production and accumulation of polyphenol-like compounds that could further inhibit extracellular enzyme activities and/or fuel the microbial communities with labile compounds. Further, increased temperatures can alter strategies of microbial communities for nutrient acquisition via changes in the activities of extracellular enzymes by priming SOM decomposition, leading to enhanced CO2 emission from peatlands. Therefore, coupled biotic and abiotic processes need to be incorporated into process-based climate models to predict the fate of SOM under elevated temperatures and to project the likely impacts of environmental change on northern peatlands and CO2 emissions.
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Affiliation(s)
- Roya AminiTabrizi
- Department of Environmental Science, The University of Arizona, Tucson, AZ 85721, USA
| | - Katerina Dontsova
- Department of Environmental Science, The University of Arizona, Tucson, AZ 85721, USA
| | - Nathalia Graf Grachet
- Department of Environmental Science, The University of Arizona, Tucson, AZ 85721, USA
| | - Malak M Tfaily
- Department of Environmental Science, The University of Arizona, Tucson, AZ 85721, USA; Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, WA 99354, USA.
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An Overview of Remote Sensing Data Applications in Peatland Research Based on Works from the Period 2010–2021. LAND 2021. [DOI: 10.3390/land11010024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In the 21st century, remote sensing (RS) has become increasingly employed in many environmental studies. This paper constitutes an overview of works utilising RS methods in studies on peatlands and investigates publications from the period 2010–2021. Based on fifty-nine case studies from different climatic zones (from subarctic to subtropical), we can indicate an increase in the use of RS methods in peatland research during the last decade, which is likely a result of the greater availability of new remote sensing data sets (Sentinel 1 and 2; Landsat 8; SPOT 6 and 7) paired with the rapid development of open-source software (ESA SNAP; QGIS and SAGA GIS). In the studied works, satellite data analyses typically encompassed the following elements: land classification/identification of peatlands, changes in water conditions in peatlands, monitoring of peatland state, peatland vegetation mapping, Gross Primary Productivity (GPP), and the estimation of carbon resources in peatlands. The most frequently employed research methods, on the other hand, included: vegetation indices, soil moisture indices, water indices, supervised classification and machine learning. Remote sensing data combined with field research is deemed helpful for peatland monitoring and multi-proxy studies, and they may offer new perspectives on research at a regional level.
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19
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ter Horst AM, Santos-Medellín C, Sorensen JW, Zinke LA, Wilson RM, Johnston ER, Trubl G, Pett-Ridge J, Blazewicz SJ, Hanson PJ, Chanton JP, Schadt CW, Kostka JE, Emerson JB. Minnesota peat viromes reveal terrestrial and aquatic niche partitioning for local and global viral populations. MICROBIOME 2021; 9:233. [PMID: 34836550 PMCID: PMC8626947 DOI: 10.1186/s40168-021-01156-0] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 09/02/2021] [Indexed: 05/31/2023]
Abstract
BACKGROUND Peatlands are expected to experience sustained yet fluctuating higher temperatures due to climate change, leading to increased microbial activity and greenhouse gas emissions. Despite mounting evidence for viral contributions to these processes in peatlands underlain with permafrost, little is known about viruses in other peatlands. More generally, soil viral biogeography and its potential drivers are poorly understood at both local and global scales. Here, 87 metagenomes and five viral size-fraction metagenomes (viromes) from a boreal peatland in northern Minnesota (the SPRUCE whole-ecosystem warming experiment and surrounding bog) were analyzed for dsDNA viral community ecological patterns, and the recovered viral populations (vOTUs) were compared with our curated PIGEON database of 266,125 vOTUs from diverse ecosystems. RESULTS Within the SPRUCE experiment, viral community composition was significantly correlated with peat depth, water content, and carbon chemistry, including CH4 and CO2 concentrations, but not with temperature during the first 2 years of warming treatments. Peat vOTUs with aquatic-like signatures (shared predicted protein content with marine and/or freshwater vOTUs) were significantly enriched in more waterlogged surface peat depths. Predicted host ranges for SPRUCE vOTUs were relatively narrow, generally within a single bacterial genus. Of the 4326 SPRUCE vOTUs, 164 were previously detected in other soils, mostly peatlands. None of the previously identified 202,371 marine and freshwater vOTUs in our PIGEON database were detected in SPRUCE peat, but 0.4% of 80,714 viral clusters (VCs, grouped by predicted protein content) were shared between soil and aquatic environments. On a per-sample basis, vOTU recovery was 32 times higher from viromes compared with total metagenomes. CONCLUSIONS Results suggest strong viral "species" boundaries between terrestrial and aquatic ecosystems and to some extent between peat and other soils, with differences less pronounced at higher taxonomic levels. The significant enrichment of aquatic-like vOTUs in more waterlogged peat suggests that viruses may also exhibit niche partitioning on more local scales. These patterns are presumably driven in part by host ecology, consistent with the predicted narrow host ranges. Although more samples and increased sequencing depth improved vOTU recovery from total metagenomes, the substantially higher per-sample vOTU recovery after viral particle enrichment highlights the utility of soil viromics. Video abstract The importance of Minnesota peat viromes in revealing terrestrial and aquatic niche partitioning for viral populations.
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Affiliation(s)
| | | | - Jackson W. Sorensen
- Department of Plant Pathology, University of California, Davis, Davis, CA USA
| | - Laura A. Zinke
- Department of Plant Pathology, University of California, Davis, Davis, CA USA
| | - Rachel M. Wilson
- Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL USA
| | - Eric R. Johnston
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Gareth Trubl
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA USA
| | - Jennifer Pett-Ridge
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA USA
| | - Steven J. Blazewicz
- Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA USA
| | - Paul J. Hanson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN USA
| | - Jeffrey P. Chanton
- Department of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL USA
| | | | - Joel E. Kostka
- Schools of Biology and Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA USA
- Center for Microbial Dynamics and Infection, Georgia Institute of Technology, Atlanta, GA 30332 USA
| | - Joanne B. Emerson
- Department of Plant Pathology, University of California, Davis, Davis, CA USA
- Genome Center, University of California, Davis, Davis, CA USA
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Kolari THM, Sallinen A, Wolff F, Kumpula T, Tolonen K, Tahvanainen T. Ongoing Fen–Bog Transition in a Boreal Aapa Mire Inferred from Repeated Field Sampling, Aerial Images, and Landsat Data. Ecosystems 2021. [DOI: 10.1007/s10021-021-00708-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
AbstractNorthern aapa mire complexes are characterized by patterned fens with flarks (wet fen surfaces) and bog zone margins with Sphagnum moss cover. Evidence exists of a recent increase in Sphagnum over fens that can alter ecosystem functions. Contrast between flarks and Sphagnum moss cover may enable remote sensing of these changes with satellite proxies. We explored recent changes in hydro-morphological patterns and vegetation in a south-boreal aapa mire in Finland and tested the performance of Landsat bands and indices in detecting Sphagnum increase in aapa mires. We combined aerial image analysis and vegetation survey, repeated after 60 years, to support Landsat satellite image analysis. Aerial image analysis revealed a decrease in flark area by 46% between 1947 and 2019. Repeated survey showed increase in Sphagnum mosses (S. pulchrum, S. papillosum) and deep-rooted vascular plants (Menyanthes trifoliata, Carex rostrata). A supervised classification of high-resolution UAV image recognized the legacy of infilled flarks in the patterning of Sphagnum carpets. Among Landsat variables, all separate spectral bands, the Green Difference Vegetation Index (GDVI), and the Automated Water Extraction Index (AWEI) correlated with the flark area. Between 1985 and 2020, near-infrared (NIR) and GDVI increased in the central flark area, and AWEI decreased throughout the mire area. In aapa mire complexes, flark fen and Sphagnum bog zones have contrasting Landsat NIR reflectance, and NIR band is suggested for monitoring changes in flarks. The observed increase in Sphagnum mosses supports the interpretation of ongoing fen–bog transitions in Northern European aapa mires, indicating significant ecosystem-scale changes.
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21
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Drivers controlling spatial and temporal variation of microbial properties and dissolved organic forms (DOC and DON) in fen soils with persistently low water tables. Glob Ecol Conserv 2021. [DOI: 10.1016/j.gecco.2021.e01605] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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The Rhizosphere Responds: Rich Fen Peat and Root Microbial Ecology after Long-Term Water Table Manipulation. Appl Environ Microbiol 2021; 87:e0024121. [PMID: 33811029 DOI: 10.1128/aem.00241-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hydrologic shifts due to climate change will affect the cycling of carbon (C) stored in boreal peatlands. Carbon cycling in these systems is carried out by microorganisms and plants in close association. This study investigated the effects of experimentally manipulated water tables (lowered and raised) and plant functional groups on the peat and root microbiomes in a boreal rich fen. All samples were sequenced and processed for bacterial, archaeal (16S DNA genes; V4), and fungal (internal transcribed spacer 2 [ITS2]) DNA. Depth had a strong effect on microbial and fungal communities across all water table treatments. Bacterial and archaeal communities were most sensitive to the water table treatments, particularly at the 10- to 20-cm depth; this area coincides with the rhizosphere or rooting zone. Iron cyclers, particularly members of the family Geobacteraceae, were enriched around the roots of sedges, horsetails, and grasses. The fungal community was affected largely by plant functional group, especially cinquefoils. Fungal endophytes (particularly Acephala spp.) were enriched in sedge and grass roots, which may have underappreciated implications for organic matter breakdown and cycling. Fungal lignocellulose degraders were enriched in the lowered water table treatment. Our results were indicative of two main methanogen communities, a rooting zone community dominated by the archaeal family Methanobacteriaceae and a deep peat community dominated by the family Methanomicrobiaceae. IMPORTANCE This study demonstrated that roots and the rooting zone in boreal fens support organisms likely capable of methanogenesis, iron cycling, and fungal endophytic association and are directly or indirectly affecting carbon cycling in these ecosystems. These taxa, which react to changes in the water table and associate with roots and, particularly, graminoids, may gain greater biogeochemical influence, as projected higher precipitation rates could lead to an increased abundance of sedges and grasses in boreal fens.
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23
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Wang Y, Xu S, Zhang W, Li Y, Wang N, He X, Chen W. Responses of growth, photosynthesis and related physiological characteristics in leaves of Acer ginnala Maxim. to increasing air temperature and/or elevated O 3. PLANT BIOLOGY (STUTTGART, GERMANY) 2021; 23 Suppl 1:221-231. [PMID: 33527649 DOI: 10.1111/plb.13240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 01/12/2021] [Accepted: 01/21/2021] [Indexed: 05/26/2023]
Abstract
Regional warming and atmospheric ozone (O3 ) pollution are two of the most important environmental issues, and commonly coexist in many areas. Both factors have an intense impact on plants. However, little information is available on the combined and interactive effects of air warming and elevated O3 concentrations on physiological characteristics of plants. To explore this issue, we studied variations in growth, photosynthesis and physiological characteristics of leaves of Acer ginnala seedlings exposed to control (ambient temperature and O3 ), increasing air temperature (ambient temperature + 2 °C), elevated O3 (ambient O3 concentration + 40 ppb) and a combination of the two abiotic factors at different phenological stages by using open-top chambers. The results showed that increasing air temperature had no significant effect on growth, but increased photosynthesis and antioxidant enzyme activity at the leaf unfolding and defoliation stages. In contrast, elevated O3 decreased growth and photosynthesis and caused oxidative stress injury in A. ginnala leaves at each phenological stage. The combination of increasing air temperature and elevated O3 improved growth and net photosynthetic rates of tested plants and alleviated the oxidative stress compared to O3 alone. Our findings demonstrated that moderate warming was beneficial to A. ginnala at leaf unfolding and defoliation stages, and alleviated the adverse effects of O3 stress on growth, photosynthesis and the antioxidant system. These results will provide a theoretical reference and scientific basis for the adaptation and response of A. ginnala under regional air warming and atmospheric O3 pollution.
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Affiliation(s)
- Y Wang
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - S Xu
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
- Chinese Academy of Sciences Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China
| | - W Zhang
- College of Environment, Shenyang University, 110044, China
| | - Y Li
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China
| | - N Wang
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
| | - X He
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
- Chinese Academy of Sciences Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China
- Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China
| | - W Chen
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
- University of the Chinese Academy of Sciences, Beijing, 100049, China
- Chinese Academy of Sciences Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Shenyang, 110016, China
- Shenyang Arboretum, Chinese Academy of Sciences, Shenyang, 110016, China
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24
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Warren JM, Jensen AM, Ward EJ, Guha A, Childs J, Wullschleger SD, Hanson PJ. Divergent species-specific impacts of whole ecosystem warming and elevated CO 2 on vegetation water relations in an ombrotrophic peatland. GLOBAL CHANGE BIOLOGY 2021; 27:1820-1835. [PMID: 33528056 DOI: 10.1111/gcb.15543] [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: 07/03/2020] [Revised: 01/08/2021] [Accepted: 01/11/2021] [Indexed: 06/12/2023]
Abstract
Boreal peatland forests have relatively low species diversity and thus impacts of climate change on one or more dominant species could shift ecosystem function. Despite abundant soil water availability, shallowly rooted vascular plants within peatlands may not be able to meet foliar demand for water under drought or heat events that increase vapor pressure deficits while reducing near surface water availability, although concurrent increases in atmospheric CO2 could buffer resultant hydraulic stress. We assessed plant water relations of co-occurring shrub (primarily Rhododendron groenlandicum and Chamaedaphne calyculata) and tree (Picea mariana and Larix laricina) species prior to, and in response to whole ecosystem warming (0 to +9°C) and elevated CO2 using 12.8-m diameter open-top enclosures installed within an ombrotrophic bog. Water relations (water potential [Ψ], turgor loss point, foliar and root hydraulic conductivity) were assessed prior to treatment initiation, then Ψ and peak sap flow (trees only) assessed after 1 or 2 years of treatments. Under the higher temperature treatments, L. laricina Ψ exceeded its turgor loss point, increased its peak sap flow, and was not able to recover Ψ overnight. In contrast, P. mariana operated below its turgor loss point and maintained constant Ψ and sap flow across warming treatments. Similarly, C. calyculata Ψ stress increased with temperature while R. groenlandicum Ψ remained at pretreatment levels. The more anisohydric behavior of L. laricina and C. calyculata may provide greater net C uptake with warming, while the more conservative P. mariana and R. groenlandicum maintained greater hydraulic safety. These latter species also responded to elevated CO2 by reduced Ψ stress, which may also help limit hydraulic failure during periods of extreme drought or heat in the future. Along with Sphagnum moss, the species-specific responses of peatland vascular communities to drier or hotter conditions will shape boreal peatland composition and function in the future.
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Affiliation(s)
- Jeffrey M Warren
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Anna M Jensen
- Department of Forestry and Wood Technology, Linnaeus University, Växjö, Sweden
| | - Eric J Ward
- U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, LA, USA
| | - Anirban Guha
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Joanne Childs
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Stan D Wullschleger
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Paul J Hanson
- Environmental Sciences Division and Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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25
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Malhotra A, Brice DJ, Childs J, Graham JD, Hobbie EA, Vander Stel H, Feron SC, Hanson PJ, Iversen CM. Peatland warming strongly increases fine-root growth. Proc Natl Acad Sci U S A 2020; 117:17627-17634. [PMID: 32661144 PMCID: PMC7395547 DOI: 10.1073/pnas.2003361117] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Belowground climate change responses remain a key unknown in the Earth system. Plant fine-root response is especially important to understand because fine roots respond quickly to environmental change, are responsible for nutrient and water uptake, and influence carbon cycling. However, fine-root responses to climate change are poorly constrained, especially in northern peatlands, which contain up to two-thirds of the world's soil carbon. We present fine-root responses to warming between +2 °C and 9 °C above ambient conditions in a whole-ecosystem peatland experiment. Warming strongly increased fine-root growth by over an order of magnitude in the warmest treatment, with stronger responses in shrubs than in trees or graminoids. In the first year of treatment, the control (+0 °C) shrub fine-root growth of 0.9 km m-2 y-1 increased linearly by 1.2 km m-2 y-1 (130%) for every degree increase in soil temperature. An extended belowground growing season accounted for 20% of this dramatic increase. In the second growing season of treatment, the shrub warming response rate increased to 2.54 km m-2 °C-1 Soil moisture was negatively correlated with fine-root growth, highlighting that drying of these typically water-saturated ecosystems can fuel a surprising burst in shrub belowground productivity, one possible mechanism explaining the "shrubification" of northern peatlands in response to global change. This previously unrecognized mechanism sheds light on how peatland fine-root response to warming and drying could be strong and rapid, with consequences for the belowground growing season duration, microtopography, vegetation composition, and ultimately, carbon function of these globally relevant carbon sinks.
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Affiliation(s)
- Avni Malhotra
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830;
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37830
| | - Deanne J Brice
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37830
| | - Joanne Childs
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37830
| | - Jake D Graham
- Department of Geosciences, Boise State University, Boise, ID 83725
| | - Erik A Hobbie
- Earth Systems Research Center, University of New Hampshire, Durham, NH 03824
| | - Holly Vander Stel
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37830
- Kellogg Biological Station, Michigan State University, Hickory Corners, MI 49060
| | - Sarah C Feron
- Department of Physics, Universidad de Santiago de Chile, Santiago, 9170022, Chile
- School of Earth, Energy and Environmental Sciences, Department of Earth System Science, Stanford University, Stanford, CA 94305
| | - Paul J Hanson
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37830
| | - Colleen M Iversen
- Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37830
- Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37830
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26
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Zhang H, Väliranta M, Piilo S, Amesbury MJ, Aquino-López MA, Roland TP, Salminen-Paatero S, Paatero J, Lohila A, Tuittila ES. Decreased carbon accumulation feedback driven by climate-induced drying of two southern boreal bogs over recent centuries. GLOBAL CHANGE BIOLOGY 2020; 26:2435-2448. [PMID: 31961026 DOI: 10.1111/gcb.15005] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/21/2019] [Accepted: 01/07/2020] [Indexed: 06/10/2023]
Abstract
Northern boreal peatlands are important ecosystems in modulating global biogeochemical cycles, yet their biological communities and related carbon dynamics are highly sensitive to changes in climate. Despite this, the strength and recent direction of these feedbacks are still unclear. The response of boreal peatlands to climate warming has received relatively little attention compared with other northern peatland types, despite forming a large northern hemisphere-wide ecosystem. Here, we studied the response of two ombrotrophic boreal peatlands to climate variability over the last c. 200 years for which local meteorological data are available. We used remains from plants and testate amoebae to study historical changes in peatland biological communities. These data were supplemented by peat property (bulk density, carbon and nitrogen content), 14 C, 210 Pb and 137 Cs analyses and were used to infer changes in peatland hydrology and carbon dynamics. In total, six peat cores, three per study site, were studied that represent different microhabitats: low hummock (LH), high lawn and low lawn. The data show a consistent drying trend over recent centuries, represented mainly as a change from wet habitat Sphagnum spp. to dry habitat S. fuscum. Summer temperature and precipitation appeared to be important drivers shaping peatland community and surface moisture conditions. Data from the driest microhabitat studied, LH, revealed a clear and strong negative linear correlation (R2 = .5031; p < .001) between carbon accumulation rate and peat surface moisture conditions: under dry conditions, less carbon was accumulated. This suggests that at the dry end of the moisture gradient, availability of water regulates carbon accumulation. It can be further linked to the decreased abundance of mixotrophic testate amoebae under drier conditions (R2 = .4207; p < .001). Our study implies that if effective precipitation decreases in the future, the carbon uptake capacity of boreal bogs may be threatened.
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Affiliation(s)
- Hui Zhang
- Institute for Atmospheric and Earth System Research (INAR), Department of Physics, University of Helsinki, Helsinki, Finland
- Environmental Change Research Unit (ECRU), Ecosystems and Environment Research Programme, University of Helsinki, Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), Helsinki, Finland
| | - Minna Väliranta
- Environmental Change Research Unit (ECRU), Ecosystems and Environment Research Programme, University of Helsinki, Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), Helsinki, Finland
| | - Sanna Piilo
- Environmental Change Research Unit (ECRU), Ecosystems and Environment Research Programme, University of Helsinki, Helsinki, Finland
- Helsinki Institute of Sustainability Science (HELSUS), Helsinki, Finland
| | - Matthew J Amesbury
- Environmental Change Research Unit (ECRU), Ecosystems and Environment Research Programme, University of Helsinki, Helsinki, Finland
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | - Thomas P Roland
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, UK
| | | | | | - Annalea Lohila
- Institute for Atmospheric and Earth System Research (INAR), Department of Physics, University of Helsinki, Helsinki, Finland
- Finnish Meteorological Institute, Helsinki, Finland
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27
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When the Source of Flooding Matters: Divergent Responses in Carbon Fluxes in an Alaskan Rich Fen to Two Types of Inundation. Ecosystems 2019. [DOI: 10.1007/s10021-019-00460-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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28
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Jassey VEJ, Signarbieux C. Effects of climate warming on Sphagnum photosynthesis in peatlands depend on peat moisture and species-specific anatomical traits. GLOBAL CHANGE BIOLOGY 2019; 25:3859-3870. [PMID: 31502398 DOI: 10.1111/gcb.14788] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Accepted: 07/16/2019] [Indexed: 06/10/2023]
Abstract
Climate change will influence plant photosynthesis by altering patterns of temperature and precipitation, including their variability and seasonality. Both effects may be important for peatlands as the carbon (C) sink potential of these ecosystems depends on the balance between plant C uptake through photosynthesis and microbial decomposition. Here, we show that the effect of climate warming on Sphagnum community photosynthesis toggles from positive to negative as the peatland goes from rainy to dry periods during summer. More particularly, we show that mechanisms of compensation among the dominant Sphagnum species (Sphagnum fallax and Sphagnum medium) stabilize the average photosynthesis and productivity of the Sphagnum community during summer despite rising temperatures and frequent droughts. While warming had a negligible effect on S. medium photosynthetic capacity (Amax ) during rainy periods, Amax of S. fallax increased by 40%. On the opposite, warming exacerbated the negative effects of droughts on S. fallax with an even sharper decrease of its Amax while S. medium Amax remained unchanged. S. medium showed a remarkable resistance to droughts due to anatomical traits favouring its water holding capacity. Our results show that different phenotypic plasticity among dominant Sphagnum species allow the community to cope with rising temperatures and repeated droughts, maintaining similar photosynthesis and productivity over summer in warmed and control conditions. These results are important because they provide information on how soil water content may modulate the effects of climate warming on Sphagnum productivity in boreal peatlands. It further confirms the transitory nature of warming-induced photosynthesis benefits in boreal systems and highlights the vulnerability of the ecosystem to excess warming and drying.
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Affiliation(s)
- Vincent E J Jassey
- Laboratoire d'Ecologie Fonctionnelle et Environnement, CNRS-INPT, Université de Toulouse, Toulouse, France
- School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Systems Laboratory (ECOS), Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
- WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Lausanne, Switzerland
| | - Constant Signarbieux
- School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Systems Laboratory (ECOS), Ecole Polytechnique Fédérale de Lausanne EPFL, Lausanne, Switzerland
- WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Lausanne, Switzerland
- Institute of Geography, University of Neuchatel, Neuchatel, Switzerland
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29
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Norby RJ, Childs J, Hanson PJ, Warren JM. Rapid loss of an ecosystem engineer: Sphagnum decline in an experimentally warmed bog. Ecol Evol 2019; 9:12571-12585. [PMID: 31788198 PMCID: PMC6875578 DOI: 10.1002/ece3.5722] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/13/2019] [Accepted: 09/15/2019] [Indexed: 01/16/2023] Open
Abstract
Sphagnum mosses are keystone components of peatland ecosystems. They facilitate the accumulation of carbon in peat deposits, but climate change is predicted to expose peatland ecosystem to sustained and unprecedented warming leading to a significant release of carbon to the atmosphere. Sphagnum responses to climate change, and their interaction with other components of the ecosystem, will determine the future trajectory of carbon fluxes in peatlands. We measured the growth and productivity of Sphagnum in an ombrotrophic bog in northern Minnesota, where ten 12.8-m-diameter plots were exposed to a range of whole-ecosystem (air and soil) warming treatments (+0 to +9°C) in ambient or elevated (+500 ppm) CO2. The experiment is unique in its spatial and temporal scale, a focus on response surface analysis encompassing the range of elevated temperature predicted to occur this century, and consideration of an effect of co-occurring CO2 altering the temperature response surface. In the second year of warming, dry matter increment of Sphagnum increased with modest warming to a maximum at 5°C above ambient and decreased with additional warming. Sphagnum cover declined from close to 100% of the ground area to <50% in the warmest enclosures. After three years of warming, annual Sphagnum productivity declined linearly with increasing temperature (13-29 g C/m2 per °C warming) due to widespread desiccation and loss of Sphagnum. Productivity was less in elevated CO2 enclosures, which we attribute to increased shading by shrubs. Sphagnum desiccation and growth responses were associated with the effects of warming on hydrology. The rapid decline of the Sphagnum community with sustained warming, which appears to be irreversible, can be expected to have many follow-on consequences to the structure and function of this and similar ecosystems, with significant feedbacks to the global carbon cycle and climate change.
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Affiliation(s)
- Richard J. Norby
- Environmental Sciences Division and Climate Change Science InstituteOak Ridge National LaboratoryOak RidgeTNUSA
| | - Joanne Childs
- Environmental Sciences Division and Climate Change Science InstituteOak Ridge National LaboratoryOak RidgeTNUSA
| | - Paul J. Hanson
- Environmental Sciences Division and Climate Change Science InstituteOak Ridge National LaboratoryOak RidgeTNUSA
| | - Jeffrey M. Warren
- Environmental Sciences Division and Climate Change Science InstituteOak Ridge National LaboratoryOak RidgeTNUSA
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30
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Haynes KM, Kane ES, Potvin L, Lilleskov EA, Kolka RK, Mitchell CPJ. Impacts of experimental alteration of water table regime and vascular plant community composition on peat mercury profiles and methylmercury production. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 682:611-622. [PMID: 31129544 DOI: 10.1016/j.scitotenv.2019.05.072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 04/22/2019] [Accepted: 05/06/2019] [Indexed: 06/09/2023]
Abstract
Climate change is expected to alter the hydrology and vascular plant communities in peatland ecosystems. These changes may have as yet unexplored impacts on peat mercury (Hg) concentrations and net methylmercury (MeHg) production. In this study, peat was collected from PEATcosm, an outdoor, controlled mesocosm experiment where peatland water table regimes and vascular plant functional groups were manipulated over several years to simulate potential climate change effects. Potential Hg(II) methylation and MeHg demethylation rate constants were assessed using enriched stable isotope incubations at the end of the study in 2015, and ambient peat total Hg (THg) and MeHg concentration depth profiles were tracked annually from 2011 to 2014. Peat THg and MeHg concentrations and the proportion of THg methylated (%MeHg) increased significantly within the zone of water table fluctuation when water tables were lowered, but potential Hg(II) methylation rate constants were similar regardless of water table treatment. When sedges dominate over ericaceous shrubs, MeHg concentrations and %MeHg became significantly elevated within the sedge rooting zone. Increased desorption of Hg(II) and MeHg from the solid phase peat into pore water occurred with a lowered water table and predominant sedge cover, likely due to greater aerobic peat decomposition. Deeper, more variable water tables and a transition to sedge-dominated communities coincided with increased MeHg accumulation within the zone of water table fluctuation. Sustained high water tables promoted the net downward migration of Hg(II) and MeHg. The simultaneous decrease in Hg(II) and MeHg concentrations in the near-surface peat and accumulation deeper in the peat profile, combined with the trends in Hg(II) and MeHg partitioning to mobile pore waters, suggest that changes to peatland hydrology and vascular plant functional groups redistribute peat Hg(II) and MeHg via vertical hydrochemical transport mechanisms.
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Affiliation(s)
- Kristine M Haynes
- University of Toronto Scarborough, Department of Physical and Environmental Sciences, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada; University of Toronto, Department of Geography, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada.
| | - Evan S Kane
- Michigan Technological University, School of Forest Resources and Environmental Science, Houghton, MI 49931, USA; USDA Forest Service Northern Research Station, Houghton, MI 49931, USA
| | - Lynette Potvin
- USDA Forest Service Northern Research Station, Houghton, MI 49931, USA
| | - Erik A Lilleskov
- USDA Forest Service Northern Research Station, Houghton, MI 49931, USA
| | - Randall K Kolka
- USDA Forest Service Northern Research Station, Grand Rapids, MN 55744, USA
| | - Carl P J Mitchell
- University of Toronto Scarborough, Department of Physical and Environmental Sciences, 1265 Military Trail, Toronto, Ontario M1C 1A4, Canada; University of Toronto, Department of Geography, 100 St. George Street, Toronto, Ontario M5S 3G3, Canada
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31
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Mekonnen ZA, Riley WJ, Randerson JT, Grant RF, Rogers BM. Expansion of high-latitude deciduous forests driven by interactions between climate warming and fire. NATURE PLANTS 2019; 5:952-958. [PMID: 31451797 DOI: 10.1038/s41477-019-0495-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 07/16/2019] [Indexed: 05/12/2023]
Abstract
High-latitude regions have experienced rapid warming in recent decades, and this trend is projected to continue over the twenty-first century1. Fire is also projected to increase with warming2,3. We show here, consistent with changes during the Holocene4, that changes in twenty-first century climate and fire are likely to alter the composition of Alaskan boreal forests. We hypothesize that competition for nutrients after fire in early succession and for light in late succession in a warmer climate will cause shifts in plant functional type. Consistent with observations, our ecosystem model predicts evergreen conifers to be the current dominant tree type in Alaska. However, under future climate and fire, our analysis suggests the relative dominance of deciduous broadleaf trees nearly doubles, accounting for 58% of the Alaska ecosystem's net primary productivity by 2100, with commensurate declines in contributions from evergreen conifer trees and herbaceous plants. Post-fire deciduous broadleaf tree growth under a future climate is sustained from enhanced microbial nitrogen mineralization caused by warmer soils and deeper active layers, resulting in taller trees that compete more effectively for light. The expansion of deciduous broadleaf forests will affect the carbon cycle, surface energy fluxes and ecosystem function, thereby modifying important feedbacks with the climate system.
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Affiliation(s)
- Zelalem A Mekonnen
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - William J Riley
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - James T Randerson
- Department of Earth System Science, University of California, Irvine, CA, USA
| | - Robert F Grant
- Department of Renewable Resources, University of Alberta, Edmonton, Canada
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32
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Characterizing Boreal Peatland Plant Composition and Species Diversity with Hyperspectral Remote Sensing. REMOTE SENSING 2019. [DOI: 10.3390/rs11141685] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Peatlands, which account for approximately 15% of land surface across the arctic and boreal regions of the globe, are experiencing a range of ecological impacts as a result of climate change. Factors that include altered hydrology resulting from drought and permafrost thaw, rising temperatures, and elevated levels of atmospheric carbon dioxide have been shown to cause plant community compositional changes. Shifts in plant composition affect the productivity, species diversity, and carbon cycling of peatlands. We used hyperspectral remote sensing to characterize the response of boreal peatland plant composition and species diversity to warming, hydrologic change, and elevated CO2. Hyperspectral remote sensing techniques offer the ability to complete landscape-scale analyses of ecological responses to climate disturbance when paired with plot-level measurements that link ecosystem biophysical properties with spectral reflectance signatures. Working within two large ecosystem manipulation experiments, we examined climate controls on composition and diversity in two types of common boreal peatlands: a nutrient rich fen located at the Alaska Peatland Experiment (APEX) in central Alaska, and an ombrotrophic bog located in northern Minnesota at the Spruce and Peatland Responses Under Changing Environments (SPRUCE) experiment. We found a strong effect of plant functional cover on spectral reflectance characteristics. We also found a positive relationship between species diversity and spectral variation at the APEX field site, which is consistent with other recently published findings. Based on the results of our field study, we performed a supervised land cover classification analysis on an aerial hyperspectral dataset to map peatland plant functional types (PFTs) across an area encompassing a range of different plant communities. Our results underscore recent advances in the application of remote sensing measurements to ecological research, particularly in far northern ecosystems.
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