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Shen H, Dai Z, Zhang Q, Tong D, Su WQ, Dahlgren RA, Xu J. Postfire Phosphorus Enrichment Mitigates Nitrogen Loss in Boreal Forests. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:10611-10622. [PMID: 38836563 DOI: 10.1021/acs.est.4c01662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Net nitrogen mineralization (Nmin) and nitrification regulate soil N availability and loss after severe wildfires in boreal forests experiencing slow vegetation recovery. Yet, how microorganisms respond to postfire phosphorus (P) enrichment to alter soil N transformations remains unclear in N-limited boreal forests. Here, we investigated postfire N-P interactions using an intensive regional-scale sampling of 17 boreal forests in the Greater Khingan Mountains (Inner Mongolia-China), a laboratory P-addition incubation, and a continental-scale meta-analysis. We found that postfire soils had an increased risk of N loss by accelerated Nmin and nitrification along with low plant N demand, especially during the early vegetation recovery period. The postfire N/P imbalance created by P enrichment acts as a "N retention" strategy by inhibiting Nmin but not nitrification in boreal forests. This strategy is attributed to enhanced microbial N-use efficiency and N immobilization. Importantly, our meta-analysis found that there was a greater risk of N loss in boreal forest soils after fires than in other climatic zones, which was consistent with our results from the 17 soils in the Greater Khingan Mountains. These findings demonstrate that postfire N-P interactions play an essential role in mitigating N limitation and maintaining nutrient balance in boreal forests.
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Affiliation(s)
- Haojie Shen
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
| | - Zhongmin Dai
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
- The Rural Development Academy, Zhejiang University, Hangzhou 310058, China
| | - Qianqian Zhang
- State Key Laboratory of Subtropical Silviculture, Zhejiang A&F University, Hangzhou 311300, China
| | - Di Tong
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
| | - Wei-Qin Su
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
| | - Randy A Dahlgren
- Department of Land, Air and Water Resources, University of California, Davis, California 95616, United States
| | - Jianming Xu
- Institute of Soil and Water Resources and Environmental Science, College of Environmental and Resource Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
- Zhejiang Provincial Key Laboratory of Agricultural Resources and Environment, Zhejiang University, 866 Yuhangtang Road, Hangzhou 310058, China
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2
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Jones BM, Kanevskiy MZ, Shur Y, Gaglioti BV, Jorgenson MT, Ward Jones MK, Veremeeva A, Miller EA, Jandt R. Post-fire stabilization of thaw-affected permafrost terrain in northern Alaska. Sci Rep 2024; 14:8499. [PMID: 38605076 PMCID: PMC11009396 DOI: 10.1038/s41598-024-58998-5] [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: 01/13/2024] [Accepted: 04/05/2024] [Indexed: 04/13/2024] Open
Abstract
In 2007, the Anaktuvuk River fire burned more than 1000 km2 of arctic tundra in northern Alaska, ~ 50% of which occurred in an area with ice-rich syngenetic permafrost (Yedoma). By 2014, widespread degradation of ice wedges was apparent in the Yedoma region. In a 50 km2 area, thaw subsidence was detected across 15% of the land area in repeat airborne LiDAR data acquired in 2009 and 2014. Updating observations with a 2021 airborne LiDAR dataset show that additional thaw subsidence was detected in < 1% of the study area, indicating stabilization of the thaw-affected permafrost terrain. Ground temperature measurements between 2010 and 2015 indicated that the number of near-surface soil thawing-degree-days at the burn site were 3 × greater than at an unburned control site, but by 2022 the number was reduced to 1.3 × greater. Mean annual ground temperature of the near-surface permafrost increased by 0.33 °C/yr in the burn site up to 7-years post-fire, but then cooled by 0.15 °C/yr in the subsequent eight years, while temperatures at the control site remained relatively stable. Permafrost cores collected from ice-wedge troughs (n = 41) and polygon centers (n = 8) revealed the presence of a thaw unconformity, that in most cases was overlain by a recovered permafrost layer that averaged 14.2 cm and 18.3 cm, respectively. Taken together, our observations highlight that the initial degradation of ice-rich permafrost following the Anaktuvuk River tundra fire has been followed by a period of thaw cessation, permafrost aggradation, and terrain stabilization.
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Affiliation(s)
- Benjamin M Jones
- Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA.
| | - Mikhail Z Kanevskiy
- Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Yuri Shur
- College of Engineering and Mines, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Benjamin V Gaglioti
- Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | | | - Melissa K Ward Jones
- Institute of Northern Engineering, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
| | - Alexandra Veremeeva
- Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Potsdam, Germany
| | - Eric A Miller
- Bureau of Land Management Alaska Fire Service, Fort Wainwright, AK, 99703, USA
| | - Randi Jandt
- Alaska Fire Science Consortium, University of Alaska Fairbanks, Fairbanks, AK, 99775, USA
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3
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Kuzmina D, Lim AG, Loiko SV, Pokrovsky OS. Experimental assessment of tundra fire impact on element export and storage in permafrost peatlands. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 853:158701. [PMID: 36108862 DOI: 10.1016/j.scitotenv.2022.158701] [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: 06/29/2022] [Revised: 09/07/2022] [Accepted: 09/08/2022] [Indexed: 06/15/2023]
Abstract
Extensive studies have been performed on wildfire impact on terrestrial and aquatic ecosystems in the taiga biome, however consequences of wildfires in the tundra biome remain poorly understood. In such a biome, permafrost peatlands occupy a sizable territory in the Northern Hemisphere and present an extensive and highly vulnerable storage of organic carbon. Here we used an experimental approach to model the impact of ash produced from burning of main tundra organic constituents (i.e., moss, lichen and peat) on surrounding aquatic ecosystems. We studied the chemical composition of aqueous leachates produced during short-term (1 week) interaction of ash with distilled water and organic-rich lake water at 5 gsolid L-1 and 20 °C. The addition of ash enriched the fluid phase in major cations (i.e., Na, Ca, Mg), macro- (i.e., P, K, Si) and micronutrients (i.e., Mn, Fe, Co, Ni, Zn, Mo). This enrichment occurred over <2 days of experiment. Among 3 studied substrates, moss ash released the largest amount of macro- and micro-components into the aqueous solution. To place the obtained results in the environmental context of a peatbog watershed, we assume a fire return interval of 56 years and that the entire 0-10 cm of upper peat is subjected to fire impact. These mass balance calculations demonstrated that maximal possible delivery of elements from ash after soil burning to the hydrological network is negligibly small (<1-2 %) compared to the annual riverine export flux and element storage in thermokarst lakes. As such, even a 5-10 fold increase in tundra wildfire frequency may not sizably modify nutrient and metal fluxes and pools in the surrounding aquatic ecosystems. This result requires revisiting the current paradigm on the importance of wildfire impact on permafrost peatlands and calls a need for experimental work on other ecosystem compartments (litter, shrubs, frozen peat) which are subjected to fire events.
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Affiliation(s)
- Daria Kuzmina
- BIO-GEO-CLIM Laboratory, Tomsk State University, 36 av. Lenina, Tomsk 634004, Russia
| | - Artem G Lim
- BIO-GEO-CLIM Laboratory, Tomsk State University, 36 av. Lenina, Tomsk 634004, Russia
| | - Sergey V Loiko
- BIO-GEO-CLIM Laboratory, Tomsk State University, 36 av. Lenina, Tomsk 634004, Russia
| | - Oleg S Pokrovsky
- GET UMR 5563 CNRS University of Toulouse, 14 Avenue Edouard Belin, 31400 Toulouse, France; N Laverov Federal Center for Integrated Arctic Research, Ural Branch of the Russian Academy of Science, 23 Nab Severnoi Dviny, Arkhangelsk 163000, Russia.
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4
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Hudson AR, Peters DPC, Blair JM, Childers DL, Doran PT, Geil K, Gooseff M, Gross KL, Haddad NM, Pastore MA, Rudgers JA, Sala O, Seabloom EW, Shaver G. Cross-Site Comparisons of Dryland Ecosystem Response to Climate Change in the US Long-Term Ecological Research Network. Bioscience 2022; 72:889-907. [PMID: 36034512 PMCID: PMC9405733 DOI: 10.1093/biosci/biab134] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Long-term observations and experiments in diverse drylands reveal how ecosystems and services are responding to climate change. To develop generalities about climate change impacts at dryland sites, we compared broadscale patterns in climate and synthesized primary production responses among the eight terrestrial, nonforested sites of the United States Long-Term Ecological Research (US LTER) Network located in temperate (Southwest and Midwest) and polar (Arctic and Antarctic) regions. All sites experienced warming in recent decades, whereas drought varied regionally with multidecadal phases. Multiple years of wet or dry conditions had larger effects than single years on primary production. Droughts, floods, and wildfires altered resource availability and restructured plant communities, with greater impacts on primary production than warming alone. During severe regional droughts, air pollution from wildfire and dust events peaked. Studies at US LTER drylands over more than 40 years demonstrate reciprocal links and feedbacks among dryland ecosystems, climate-driven disturbance events, and climate change.
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Affiliation(s)
- Amy R Hudson
- Agricultural Research Service's Big Data Initiative and SCINet Program for Scientific Computing in Berwyn Heights , Maryland, United States
| | - Debra P C Peters
- Agricultural Research Service's Big Data Initiative and SCINet Program for Scientific Computing in Berwyn Heights , Maryland, United States
- US Department of Agriculture Agricultural Research Service's Jornada Experimental Range, Las Cruces , New Mexico, United States
- New Mexico State University , Las Cruces, New Mexico, United States
| | - John M Blair
- Kansas State University, Manhattan , Kansas, United States
| | | | - Peter T Doran
- Louisiana State University , Baton Rouge, Louisiana, United States
| | - Kerrie Geil
- Agricultural Research Service's Big Data Initiative and SCINet Program for Scientific Computing in Berwyn Heights , Maryland, United States
| | | | - Katherine L Gross
- W. K. Kellogg Biological Station, Vermont , United States
- Department of Plant Biology, Vermont , United States
| | - Nick M Haddad
- W. K. Kellogg Biological Station, Vermont , United States
- Department of Plant Biology, Vermont , United States
| | | | | | - Osvaldo Sala
- Arizona State University , Tempe, Arizona, United States
- Global Drylands Center and the School of Life Sciences, Arizona State University , Tempe, Arizona, United States
| | - Eric W Seabloom
- University of Minnesota , St. Paul, Minnesota, United States
| | - Gaius Shaver
- Marine Biological Laboratory, Woods Hole , Massachusetts, United States
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5
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Microbiogeochemical Traits to Identify Nitrogen Hotspots in Permafrost Regions. NITROGEN 2022. [DOI: 10.3390/nitrogen3030031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Permafrost-affected tundra soils are large carbon (C) and nitrogen (N) reservoirs. However, N is largely bound in soil organic matter (SOM), and ecosystems generally have low N availability. Therefore, microbial induced N-cycling processes and N losses were considered negligible. Recent studies show that microbial N processing rates, inorganic N availability, and lateral N losses from thawing permafrost increase when vegetation cover is disturbed, resulting in reduced N uptake or increased N input from thawing permafrost. In this review, we describe currently known N hotspots, particularly bare patches in permafrost peatland or permafrost soils affected by thermokarst, and their microbiogeochemical characteristics, and present evidence for previously unrecorded N hotspots in the tundra. We summarize the current understanding of microbial N cycling processes that promote the release of the potent greenhouse gas (GHG) nitrous oxide (N2O) and the translocation of inorganic N from terrestrial into aquatic ecosystems. We suggest that certain soil characteristics and microbial traits can be used as indicators of N availability and N losses. Identifying N hotspots in permafrost soils is key to assessing the potential for N release from permafrost-affected soils under global warming, as well as the impact of increased N availability on emissions of carbon-containing GHGs.
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6
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Mason RE, Craine JM, Lany NK, Jonard M, Ollinger SV, Groffman PM, Fulweiler RW, Angerer J, Read QD, Reich PB, Templer PH, Elmore AJ. Evidence, causes, and consequences of declining nitrogen availability in terrestrial ecosystems. Science 2022; 376:eabh3767. [PMID: 35420945 DOI: 10.1126/science.abh3767] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The productivity of ecosystems and their capacity to support life depends on access to reactive nitrogen (N). Over the past century, humans have more than doubled the global supply of reactive N through industrial and agricultural activities. However, long-term records demonstrate that N availability is declining in many regions of the world. Reactive N inputs are not evenly distributed, and global changes-including elevated atmospheric carbon dioxide (CO2) levels and rising temperatures-are affecting ecosystem N supply relative to demand. Declining N availability is constraining primary productivity, contributing to lower leaf N concentrations, and reducing the quality of herbivore diets in many ecosystems. We outline the current state of knowledge about declining N availability and propose actions aimed at characterizing and responding to this emerging challenge.
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Affiliation(s)
- Rachel E Mason
- National Socio-Environmental Synthesis Center, Annapolis, MD, USA
| | | | - Nina K Lany
- Northern Research Station, USDA Forest Service, Durham, NH, USA
| | - Mathieu Jonard
- Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - Scott V Ollinger
- Earth Systems Research Center, University of New Hampshire, Durham, NH, USA
| | - Peter M Groffman
- Advanced Science Research Center, The Graduate Center, City University of New York, New York, NY, USA.,Cary Institute of Ecosystem Studies, Millbrook, NY, USA
| | - Robinson W Fulweiler
- Department of Earth and Environment, Boston University, Boston, MA, USA.,Department of Biology, Boston University, Boston, MA, USA
| | - Jay Angerer
- Fort Keogh Livestock and Range Research Laboratory, USDA Agricultural Research Service, Miles City, MT, USA
| | - Quentin D Read
- National Socio-Environmental Synthesis Center, Annapolis, MD, USA
| | - Peter B Reich
- Department of Forest Resources, University of Minnesota, St. Paul, MN, USA.,Institute for Global Change Biology and School for Environment and Sustainability, University of Michigan, Ann Arbor, MI, USA.,Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | | | - Andrew J Elmore
- National Socio-Environmental Synthesis Center, Annapolis, MD, USA.,Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, MD, USA
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7
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Steketee JK, Rocha AV, Gough L, Griffin KL, Klupar I, An R, Williamson N, Rowe RJ. Small herbivores with big impacts: Tundra voles (Microtus oeconomus) alter post-fire ecosystem dynamics. Ecology 2022; 103:e3689. [PMID: 35324006 DOI: 10.1002/ecy.3689] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 10/14/2021] [Accepted: 10/28/2021] [Indexed: 11/11/2022]
Abstract
Fire is an important ecological disturbance that can reset ecosystems and initiate changes in plant community composition, ecosystem biogeochemistry, and primary productivity. Since herbivores rely on primary producers for food, changes in vegetation may alter plant-herbivore interactions with important - but often unexplored - feedbacks to ecosystems. Here we examined the impact of post-fire changes in plant community composition and structure on habitat suitability and rodent herbivore activity in response to a large, severe, and unprecedented fire in northern Alaskan tundra. In moist acidic tundra where the fire occurred, tundra voles (Microtus oeconomus) are the dominant herbivore and rely on the tussock forming sedge Eriophorum vaginatum for both food and nesting material. Seven to twelve years after the fire, tundra voles were 10 times more abundant at the burned site compared to nearby unburned tundra. Fire increased habitat suitability for voles by increasing plant productivity and biomass, food quality, and cover through both taller vegetation and increased microtopography. As a result of elevated vole abundance, Eriophorum mortality caused by vole herbivory was two orders of magnitude higher than natural mortality and approached the magnitude of the mortality rate resulting directly from the fire. These findings suggest that post-fire increases in herbivore pressure on Eriophorum could, in turn, disrupt graminoid recovery and enhance shrub encroachment. Tundra state transitions from graminoid to shrub dominated are also evident following other disturbances and fertilization experiments, suggesting that as Arctic temperatures rise, greater available nutrients and increased frequencies of large-scale disturbances may also alter plant-animal interactions with cascading impacts on plant communities and ecosystem function.
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Affiliation(s)
- Jess K Steketee
- Natural Resources and the Environment, University of New Hampshire, 114 James Hall, 56 College Road, Durham, NH, USA
| | - Adrian V Rocha
- Department of Biological Sciences and the Environmental Change Initiative, University of Notre Dame, Notre Dame, IN, USA
| | - Laura Gough
- Department of Biological Sciences, Towson University, Towson, Maryland, USA
| | - Kevin L Griffin
- Department of Ecology, Evolution and Environmental Biology, Columbia University, New York, NY, USA.,Department of Earth and Environmental Sciences, Columbia University, Palisades, NY, USA.,Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
| | - Ian Klupar
- Department of Biological Sciences and the Environmental Change Initiative, University of Notre Dame, Notre Dame, IN, USA
| | - Ruby An
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ
| | - Nicole Williamson
- Department of Biological Sciences, Towson University, Towson, Maryland, USA
| | - Rebecca J Rowe
- Natural Resources and the Environment, University of New Hampshire, 114 James Hall, 56 College Road, Durham, NH, USA
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8
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Chen Y, Kelly R, Genet H, Lara MJ, Chipman ML, McGuire AD, Hu FS. Resilience and sensitivity of ecosystem carbon stocks to fire-regime change in Alaskan tundra. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151482. [PMID: 34742811 DOI: 10.1016/j.scitotenv.2021.151482] [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: 07/23/2021] [Revised: 11/02/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
Fire disturbance has increased in some tundra ecosystems due to anthropogenic climate change, with important ramifications for terrestrial carbon cycling. Assessment of the potential impact of fire-regime change on tundra carbon stocks requires long-term perspectives because tundra fires have been rare historically. Here we integrated the process-based Dynamic Organic Soil version of the Terrestrial Ecosystem Model with paleo-fire records to evaluate the responses of tundra carbon stocks to changes in fire return interval (FRI). Paleorecords reveal that mean FRIs of tundra ecosystems in Alaska ranged from centennial to millennial timescales (200-6000 years) during the late Quaternary, but projected FRIs by 2100 decrease to a few hundred years to several decades (70-660 years). Our simulations indicate threshold effects of changing FRIs on tundra carbon stocks. Shortening FRI from 5000 to 1000 years results in minimal carbon release (<5%) from Alaskan tundra ecosystems. Rapid carbon stock loss occurs when FRI declines below 800 years trigger sustained mobilization of ancient carbon stocks from permafrost soils. However, substantial spatial heterogeneity in the resilience/sensitivity of tundra carbon stocks to FRI change exists, largely attributable to vegetation types. We identified the carbon stocks in shrub tundra as the most vulnerable to decreasing FRI because shrub tundra stores a large share of carbon in combustible biomass and organic soils. Moreover, our results suggest that ecosystems characterized by large carbon stocks and relatively long FRIs (e.g. Brooks Foothills) may transition towards hotspots of permafrost carbon emission as a response to crossing FRI thresholds in the coming decades. These findings combined imply that fire disturbance may play an increasingly important role in future carbon balance of tundra ecosystems, but the net outcome may be strongly modulated by vegetation composition.
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Affiliation(s)
- Yaping Chen
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Ryan Kelly
- UNC Health Care System, 1025 Think Place, Morrisville, NC, USA
| | - Hélène Genet
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Mark Jason Lara
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Geography, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Melissa Lynn Chipman
- Department of Earth and Environmental Sciences, Syracuse University, Syracuse, NY, USA
| | - A David McGuire
- Institute of Arctic Biology, University of Alaska, Fairbanks, AK, USA
| | - Feng Sheng Hu
- Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Geology, University of Illinois at Urbana-Champaign, Urbana, IL, USA; Department of Biology, Washington University in Saint Louis, Saint Louis, MO, USA; Department of Earth and Planetary Sciences, Washington University in Saint Louis, Saint Louis, MO, USA.
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9
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OUP accepted manuscript. Bioscience 2022. [DOI: 10.1093/biosci/biac034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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10
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Crandall T, Jones E, Greenhalgh M, Frei RJ, Griffin N, Severe E, Maxwell J, Patch L, St. Clair SI, Bratsman S, Merritt M, Norris AJ, Carling GT, Hansen N, St. Clair SB, Abbott BW. Megafire affects stream sediment flux and dissolved organic matter reactivity, but land use dominates nutrient dynamics in semiarid watersheds. PLoS One 2021; 16:e0257733. [PMID: 34555099 PMCID: PMC8460006 DOI: 10.1371/journal.pone.0257733] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 09/08/2021] [Indexed: 01/05/2023] Open
Abstract
Climate change is causing larger wildfires and more extreme precipitation events in many regions. As these ecological disturbances increasingly coincide, they alter lateral fluxes of sediment, organic matter, and nutrients. Here, we report the stream chemistry response of watersheds in a semiarid region of Utah (USA) that were affected by a megafire followed by an extreme precipitation event in October 2018. We analyzed daily to hourly water samples at 10 stream locations from before the storm event until three weeks after its conclusion for suspended sediment, solute and nutrient concentrations, water isotopes, and dissolved organic matter concentration, optical properties, and reactivity. The megafire caused a ~2,000-fold increase in sediment flux and a ~6,000-fold increase in particulate carbon and nitrogen flux over the course of the storm. Unexpectedly, dissolved organic carbon (DOC) concentration was 2.1-fold higher in burned watersheds, despite the decreased organic matter from the fire. DOC from burned watersheds was 1.3-fold more biodegradable and 2.0-fold more photodegradable than in unburned watersheds based on 28-day dark and light incubations. Regardless of burn status, nutrient concentrations were higher in watersheds with greater urban and agricultural land use. Likewise, human land use had a greater effect than megafire on apparent hydrological residence time, with rapid stormwater signals in urban and agricultural areas but a gradual stormwater pulse in areas without direct human influence. These findings highlight how megafires and intense rainfall increase short-term particulate flux and alter organic matter concentration and characteristics. However, in contrast with previous research, which has largely focused on burned-unburned comparisons in pristine watersheds, we found that direct human influence exerted a primary control on nutrient status. Reducing anthropogenic nutrient sources could therefore increase socioecological resilience of surface water networks to changing wildfire regimes.
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Affiliation(s)
- Trevor Crandall
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
- Cimarron Valley Research Station, Oklahoma State University, Perkins, Oklahoma, United States of America
| | - Erin Jones
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Mitchell Greenhalgh
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Rebecca J. Frei
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
- Department of Renewable Resources, University of Alberta, Edmonton, Alberta, Canada
| | - Natasha Griffin
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Emilee Severe
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Jordan Maxwell
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Leika Patch
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - S. Isaac St. Clair
- Department of Statistics, Brigham Young University, Provo, Utah, United States of America
| | - Sam Bratsman
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Marina Merritt
- Department of Chemical Engineering, Brigham Young University, Provo, Utah, United States of America
| | - Adam J. Norris
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Gregory T. Carling
- Department of Geological Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Neil Hansen
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Samuel B. St. Clair
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
| | - Benjamin W. Abbott
- Department of Plant and Wildlife Sciences, Brigham Young University, Provo, Utah, United States of America
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11
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Klupar I, Rocha AV, Rastetter EB. Alleviation of nutrient co-limitation induces regime shifts in post-fire community composition and productivity in Arctic tundra. GLOBAL CHANGE BIOLOGY 2021; 27:3324-3335. [PMID: 33960082 DOI: 10.1111/gcb.15646] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Accepted: 03/21/2021] [Indexed: 06/12/2023]
Abstract
Recent unprecedented fires in the Arctic during the past two decades have indicated a pressing need to understand the long-term ecological impacts of fire in this biome. Anecdotal evidence suggests that tundra fires can induce regime shifts that change tussock tundra to more shrub-dominated ecosystems. However, the ecological mechanisms regulating these shifts are poorly understood, but are hypothesized to involve changes to nutrient availability in this nutrient limited system. Here we conducted a 4-year two-factorial (control: C, nitrogen along: N+ , phosphorus alone: P+ , nitrogen and phosphorus combined: NP+ ) fertilization experiment in both unburned and burned tundra to test this hypothesis after a decade of post-fire recovery. A decade after fire, the burned site exhibited an increase in soil nitrogen and phosphorus availability and a transition toward taller, more productive, and more deciduous vegetation. This shift in vegetation structure, composition, and function was induced at the unburned site through the addition of both NP+ and the alleviation of their co-limitation. Both burned and unburned tundra responded similarly to fertilizer treatments by increasing leaf area index, greenness, and canopy height in NP+ treatments, and exhibited no significant response in individual N+ or P+ treatments. These results point to a greater need to understand coupled carbon, nitrogen, and phosphorus cycles in this system, and suggest that post-fire regime shifts are regulated by the alleviation of nitrogen and phosphorus co-limitation in Arctic tundra.
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Affiliation(s)
- Ian Klupar
- Department of Biological Sciences and the Environmental Change Initiative, University of Notre Dame, Notre Dame, IN, USA
| | - Adrian V Rocha
- Department of Biological Sciences and the Environmental Change Initiative, University of Notre Dame, Notre Dame, IN, USA
| | - Edward B Rastetter
- Marine Biological Laboratory, The Ecosystems Center, Woods Hole, MA, USA
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