101
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Vidon P, Serchan S. Landscape geomorphic characteristic impacts on greenhouse gas fluxes in exposed stream and riparian sediments. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2016; 18:844-853. [PMID: 27306099 DOI: 10.1039/c6em00162a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
While excessive releases of greenhouse gases (GHG: N2O, CO2, CH4) to the atmosphere due to the burning of fossil fuel remains a concern, we also need to better quantify GHG emissions from natural systems. This study investigates GHG fluxes at the soil-atmosphere interface in a series of 7 stream reaches (riparian zones + exposed streambed sediment) across a range of geomorphic locations from headwaters reaches to lowland wetland reaches. When riparian fluxes (RZ) are compared to fluxes from in-stream locations (IS) under summer baseflow conditions, total CO2-equivalent (CO2eq) emissions are approximately 5 times higher at RZ locations than at IS locations, with most CO2eq driven by CH4 production at RZ locations where wet conditions dominate (headwater wetlands, lowland wetlands). On a gas-by-gas basis, no clear differences in N2O fluxes between RZ and IS locations were observed regardless of locations (headwater vs. lowland reaches), while CO2 fluxes were significantly larger at RZ locations than IS locations. Methane fluxes were significantly higher in wetland-influenced reaches than other reaches for both RZ and IS locations. However, GHG fluxes were not consistently correlated to DOC, DO, NO3(-), NH4(+), or water temperature, stressing the limitations of using water quality parameters to predict GHG emissions at the floodplain scale, at least during summer baseflow conditions. As strategies are developed to further constrain GHG emission for whole watersheds, we propose that approaches linking landscape geomorphic characteristics to GHG fluxes at the soil-atmosphere interface offer a promising avenue to successfully predict GHG emissions in floodplains at the watershed scale.
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Affiliation(s)
- Philippe Vidon
- Department of Forest and Natural Resources Management, The State University of New York College of Environmental Science and Forestry (SUNY-ESF), 1 Forestry Drive, Bray 320, Syracuse, NY 13210, USA.
| | - Satish Serchan
- Department of Forest and Natural Resources Management, The State University of New York College of Environmental Science and Forestry (SUNY-ESF), 1 Forestry Drive, Bray 320, Syracuse, NY 13210, USA.
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102
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Bond‐Lamberty B, Epron D, Harden J, Harmon ME, Hoffman F, Kumar J, David McGuire A, Vargas R. Estimating heterotrophic respiration at large scales: challenges, approaches, and next steps. Ecosphere 2016. [DOI: 10.1002/ecs2.1380] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Ben Bond‐Lamberty
- Joint Global Change Research Institute Pacific Northwest National Laboratory 5825 University Research Court College Park Maryland 20740 USA
| | - Daniel Epron
- Université de Lorraine UMR INRA‐UL 1137 Ecologie et Ecophysiologie Forestières Vandoeuvre‐les‐Nancy F54500 France
| | - Jennifer Harden
- United States Geological Survey Menlo Park California 94025 USA
| | - Mark E. Harmon
- Department of Forest Ecosystems and Society Oregon State University Corvallis Oregon 97331 USA
| | - Forrest Hoffman
- Oak Ridge National Laboratory Climate Change Science Institute Oak Ridge Tennessee 37831 USA
| | - Jitendra Kumar
- Oak Ridge National Laboratory Climate Change Science Institute Oak Ridge Tennessee 37831 USA
| | - Anthony David McGuire
- United States Geological Survey Alaska Cooperative Fish and Wildlife Research Unit University of Alaska Fairbanks Fairbanks Alaska 99775 USA
| | - Rodrigo Vargas
- Department of Plant and Soil Sciences University of Delaware Newark Delaware 19716 USA
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103
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Diáková K, Čapek P, Kohoutová I, Mpamah PA, Bárta J, Biasi C, Martikainen PJ, Šantrůčková H. Heterogeneity of carbon loss and its temperature sensitivity in East-European subarctic tundra soils. FEMS Microbiol Ecol 2016; 92:fiw140. [DOI: 10.1093/femsec/fiw140] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2016] [Indexed: 01/25/2023] Open
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104
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Gomez J, Vidon P, Gross J, Beier C, Caputo J, Mitchell M. Estimating greenhouse gas emissions at the soil-atmosphere interface in forested watersheds of the US Northeast. ENVIRONMENTAL MONITORING AND ASSESSMENT 2016; 188:295. [PMID: 27085717 DOI: 10.1007/s10661-016-5297-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 04/07/2016] [Indexed: 06/05/2023]
Abstract
Although anthropogenic emissions of greenhouse gases (GHG: CO2, CH4, N2O) are unequivocally tied to climate change, natural systems such as forests have the potential to affect GHG concentration in the atmosphere. Our study reports GHG emissions as CO2, CH4, N2O, and CO2eq fluxes across a range of landscape hydrogeomorphic classes (wetlands, riparian areas, lower hillslopes, upper hillslopes) in a forested watershed of the Northeastern USA and assesses the usability of the topographic wetness index (TWI) as a tool to identify distinct landscape geomorphic classes to aid in the development of GHG budgets at the soil atmosphere interface at the watershed scale. Wetlands were hot spots of GHG production (in CO2eq) in the landscape owing to large CH4 emission. However, on an areal basis, the lower hillslope class had the greatest influence on the net watershed CO2eq efflux, mainly because it encompassed the largest proportion of the study watershed (54 %) and had high CO2 fluxes relative to other land classes. On an annual basis, summer, fall, winter, and spring accounted for 40, 27, 9, and 24 % of total CO2eq emissions, respectively. When compared to other approaches (e.g., random or systematic sampling design), the TWI landscape classification method was successful in identifying dominant landscape hydrogeomorphic classes and offered the possibility of systematically accounting for small areas of the watershed (e.g., wetlands) that have a disproportionate effect on total GHG emissions. Overall, results indicate that soil CO2eq efflux in the Archer Creek Watershed may exceed C uptake by live trees under current conditions.
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Affiliation(s)
- Joshua Gomez
- College of Environmental Science and Forestry (SUNY-ESF), The State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
- Tectonic Engineering and Surveying Consultants P.C., Mountainville, NY, 10953, USA
| | - Philippe Vidon
- College of Environmental Science and Forestry (SUNY-ESF), The State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA.
| | - Jordan Gross
- College of Environmental Science and Forestry (SUNY-ESF), The State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Colin Beier
- College of Environmental Science and Forestry (SUNY-ESF), The State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Jesse Caputo
- College of Environmental Science and Forestry (SUNY-ESF), The State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
| | - Myron Mitchell
- College of Environmental Science and Forestry (SUNY-ESF), The State University of New York, 1 Forestry Drive, Syracuse, NY, 13210, USA
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105
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Fleischer E, Khashimov I, Hölzel N, Klemm O. Carbon exchange fluxes over peatlands in Western Siberia: Possible feedback between land-use change and climate change. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 545-546:424-433. [PMID: 26748007 DOI: 10.1016/j.scitotenv.2015.12.073] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 12/16/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
The growing demand for agricultural products has been leading to an expansion and intensification of agriculture around the world. More and more unused land is currently reclaimed in the regions of the former Soviet Union. Driven by climate change, the Western Siberian grain belt might, in a long-term, even expand into the drained peatland areas to the North. It is crucial to study the consequences of this land-use change with respect to the carbon cycling as this is still a major knowledge gap. We present for the first time data on the atmosphere-ecosystem exchange of carbon dioxide and methane of an arable field and a neighboring unused grassland on peat soil in Western Siberia. Eddy covariance measurements were performed over one vegetation period. No directed methane fluxes were found due to an effective drainage of the study sites. The carbon dioxide fluxes appeared to be of high relevance for the global carbon and greenhouse gas cycles. They showed very site-specific patterns resulting from the development of vegetation: the persistent plants of the grassland were able to start photosynthesizing soon after snow melt, while the absence of vegetation on the managed field lead to a phase of emissions until the oat plants started to grow in June. The uptake peak of the oat field is much later than that of the grassland, but larger due to a rapid plant growth. Budgeting the whole measurement period, the grassland served as a carbon sink, whereas the oat field was identified to be a carbon source. The conversion from non-used grasslands on peat soil to cultivated fields in Western Siberia is therefore considered to have a positive feedback on climate change.
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Affiliation(s)
- Elisa Fleischer
- Institute of Landscape Ecology, Climatology Research Group, University of Münster, Münster, Germany.
| | - Ilhom Khashimov
- Institute of Earth Science, Physical Geography and Geoecology Department, Tyumen State University, Tyumen, Russia.
| | - Norbert Hölzel
- Institute of Landscape Ecology, Biodiversity and Ecosystem Research Group, University of Münster, Münster, Germany.
| | - Otto Klemm
- Institute of Landscape Ecology, Climatology Research Group, University of Münster, Münster, Germany.
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106
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High-Resolution Classification of South Patagonian Peat Bog Microforms Reveals Potential Gaps in Up-Scaled CH4 Fluxes by use of Unmanned Aerial System (UAS) and CIR Imagery. REMOTE SENSING 2016. [DOI: 10.3390/rs8030173] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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107
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Krause S, Niklaus PA, Badwan Morcillo S, Meima Franke M, Lüke C, Reim A, Bodelier PLE. Compositional and functional stability of aerobic methane consuming communities in drained and rewetted peat meadows. FEMS Microbiol Ecol 2015; 91:fiv119. [PMID: 26449384 DOI: 10.1093/femsec/fiv119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/30/2015] [Indexed: 11/13/2022] Open
Abstract
The restoration of peatlands is an important strategy to counteract subsidence and loss of biodiversity. However, responses of important microbial soil processes are poorly understood. We assessed functioning, diversity and spatial organization of methanotrophic communities in drained and rewetted peat meadows with different water table management and agricultural practice. Results show that the methanotrophic diversity was similar between drained and rewetted sites with a remarkable dominance of the genus Methylocystis. Enzyme kinetics depicted no major differences, indicating flexibility in the methane (CH4) concentrations that can be used by the methanotrophic community. Short-term flooding led to temporary elevated CH4 emission but to neither major changes in abundances of methane-oxidizing bacteria (MOB) nor major changes in CH4 consumption kinetics in drained agriculturally used peat meadows. Radiolabeling and autoradiographic imaging of intact soil cores revealed a markedly different spatial arrangement of the CH4 consuming zone in cores exposed to near-atmospheric and elevated CH4. The observed spatial patterns of CH4 consumption in drained peat meadows with and without short-term flooding highlighted the spatial complexity and responsiveness of the CH4 consuming zone upon environmental change. The methanotrophic microbial community is not generally altered and harbors MOB that can cover a large range of CH4 concentrations offered due to water-table fluctuations, effectively mitigating CH4 emissions.
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Affiliation(s)
- Sascha Krause
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, 6708 PB, the Netherlands Department of Chemical Engineering, University of Washington, Seattle, WA 98195, USA
| | - Pascal A Niklaus
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich 8057, Switzerland
| | - Sara Badwan Morcillo
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, 6708 PB, the Netherlands
| | - Marion Meima Franke
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, 6708 PB, the Netherlands
| | - Claudia Lüke
- Department of Microbiology, Radboud University Nijmegen, Nijmegen, 6525 AJ, the Netherlands
| | - Andreas Reim
- Department of Biogeochemistry, Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Paul L E Bodelier
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, 6708 PB, the Netherlands
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108
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Hartley IP, Hill TC, Wade TJ, Clement RJ, Moncrieff JB, Prieto-Blanco A, Disney MI, Huntley B, Williams M, Howden NJK, Wookey PA, Baxter R. Quantifying landscape-level methane fluxes in subarctic Finland using a multiscale approach. GLOBAL CHANGE BIOLOGY 2015; 21:3712-3725. [PMID: 25969925 PMCID: PMC4989475 DOI: 10.1111/gcb.12975] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 04/27/2015] [Indexed: 06/04/2023]
Abstract
Quantifying landscape-scale methane (CH4 ) fluxes from boreal and arctic regions, and determining how they are controlled, is critical for predicting the magnitude of any CH4 emission feedback to climate change. Furthermore, there remains uncertainty regarding the relative importance of small areas of strong methanogenic activity, vs. larger areas with net CH4 uptake, in controlling landscape-level fluxes. We measured CH4 fluxes from multiple microtopographical subunits (sedge-dominated lawns, interhummocks and hummocks) within an aapa mire in subarctic Finland, as well as in drier ecosystems present in the wider landscape, lichen heath and mountain birch forest. An intercomparison was carried out between fluxes measured using static chambers, up-scaled using a high-resolution landcover map derived from aerial photography and eddy covariance. Strong agreement was observed between the two methodologies, with emission rates greatest in lawns. CH4 fluxes from lawns were strongly related to seasonal fluctuations in temperature, but their floating nature meant that water-table depth was not a key factor in controlling CH4 release. In contrast, chamber measurements identified net CH4 uptake in birch forest soils. An intercomparison between the aerial photography and satellite remote sensing demonstrated that quantifying the distribution of the key CH4 emitting and consuming plant communities was possible from satellite, allowing fluxes to be scaled up to a 100 km(2) area. For the full growing season (May to October), ~ 1.1-1.4 g CH4 m(-2) was released across the 100 km(2) area. This was based on up-scaled lawn emissions of 1.2-1.5 g CH4 m(-2) , vs. an up-scaled uptake of 0.07-0.15 g CH4 m(-2) by the wider landscape. Given the strong temperature sensitivity of the dominant lawn fluxes, and the fact that lawns are unlikely to dry out, climate warming may substantially increase CH4 emissions in northern Finland, and in aapa mire regions in general.
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Affiliation(s)
- Iain P Hartley
- Geography, College of Life and Environmental Sciences, University of Exeter, Exeter, EX4 4RJ, UK
| | - Timothy C Hill
- Department of Earth and Environmental Science, University of St Andrews, St Andrews, KY16 9AL, UK
| | - Thomas J Wade
- School of Geosciences, University of Edinburgh, Edinburgh, EH3 3JN, UK
| | - Robert J Clement
- School of Geosciences, University of Edinburgh, Edinburgh, EH3 3JN, UK
| | - John B Moncrieff
- School of Geosciences, University of Edinburgh, Edinburgh, EH3 3JN, UK
| | - Ana Prieto-Blanco
- Department of Geography, University College London, London, WC1E 6BT, UK
| | - Mathias I Disney
- Department of Geography, University College London, London, WC1E 6BT, UK
- NERC National Centre for Earth Observation (NCEO)
| | - Brian Huntley
- NERC National Centre for Earth Observation (NCEO)
- School of Biological and Biomedical Sciences, University of Durham, Durham, DH1 3LE, UK
| | - Mathew Williams
- School of Geosciences, University of Edinburgh, Edinburgh, EH3 3JN, UK
- NERC National Centre for Earth Observation (NCEO)
| | | | - Philip A Wookey
- School of Life Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK
| | - Robert Baxter
- School of Biological and Biomedical Sciences, University of Durham, Durham, DH1 3LE, UK
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109
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Knox SH, Sturtevant C, Matthes JH, Koteen L, Verfaillie J, Baldocchi D. Agricultural peatland restoration: effects of land-use change on greenhouse gas (CO2 and CH4) fluxes in the Sacramento-San Joaquin Delta. GLOBAL CHANGE BIOLOGY 2015; 21:750-765. [PMID: 25229180 DOI: 10.1111/gcb.12745] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/11/2014] [Indexed: 06/03/2023]
Abstract
Agricultural drainage of organic soils has resulted in vast soil subsidence and contributed to increased atmospheric carbon dioxide (CO2) concentrations. The Sacramento-San Joaquin Delta in California was drained over a century ago for agriculture and human settlement and has since experienced subsidence rates that are among the highest in the world. It is recognized that drained agriculture in the Delta is unsustainable in the long-term, and to help reverse subsidence and capture carbon (C) there is an interest in restoring drained agricultural land-use types to flooded conditions. However, flooding may increase methane (CH4) emissions. We conducted a full year of simultaneous eddy covariance measurements at two conventional drained agricultural peatlands (a pasture and a corn field) and three flooded land-use types (a rice paddy and two restored wetlands) to assess the impact of drained to flooded land-use change on CO2 and CH4 fluxes in the Delta. We found that the drained sites were net C and greenhouse gas (GHG) sources, releasing up to 341 g C m(-2) yr(-1) as CO2 and 11.4 g C m(-2) yr(-1) as CH4. Conversely, the restored wetlands were net sinks of atmospheric CO2, sequestering up to 397 g C m(-2) yr(-1). However, they were large sources of CH4, with emissions ranging from 39 to 53 g C m(-2) yr(-1). In terms of the full GHG budget, the restored wetlands could be either GHG sources or sinks. Although the rice paddy was a small atmospheric CO2 sink, when considering harvest and CH4 emissions, it acted as both a C and GHG source. Annual photosynthesis was similar between sites, but flooding at the restored sites inhibited ecosystem respiration, making them net CO2 sinks. This study suggests that converting drained agricultural peat soils to flooded land-use types can help reduce or reverse soil subsidence and reduce GHG emissions.
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Affiliation(s)
- Sara Helen Knox
- Ecosystem Science Division, Department of Environmental Science, Policy and Management, University of California at Berkeley, Berkeley, CA, USA
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110
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Whitfield CJ, Baulch HM, Chun KP, Westbrook CJ. Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas. AMBIO 2015; 44:7-15. [PMID: 25515021 PMCID: PMC4293363 DOI: 10.1007/s13280-014-0575-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 09/12/2014] [Accepted: 10/30/2014] [Indexed: 06/04/2023]
Abstract
Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH(4)) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH(4) emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18-0.80 Tg CH(4) year(-1) (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500-42 000 km(2) of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH(4) emissions.
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Affiliation(s)
- Colin J Whitfield
- Centre for Hydrology, Department of Geography and Planning, University of Saskatchewan, Saskatoon, SK, S7N 5C8, Canada,
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111
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Smiljanić M, Seo JW, Läänelaid A, van der Maaten-Theunissen M, Stajić B, Wilmking M. Peatland pines as a proxy for water table fluctuations: disentangling tree growth, hydrology and possible human influence. THE SCIENCE OF THE TOTAL ENVIRONMENT 2014; 500-501:52-63. [PMID: 25217744 DOI: 10.1016/j.scitotenv.2014.08.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 08/16/2014] [Accepted: 08/18/2014] [Indexed: 06/03/2023]
Abstract
Dendrochronological investigations of Scots pine (Pinus sylvestris L.) growing on Männikjärve peatland in central Estonia showed that annual tree growth of peatland pines can be used as a proxy for past variations of water table levels. Reconstruction of past water table levels can help us to better understand the dynamics of various ecological processes in peatlands, e.g. the formation of vegetation patterns or carbon and nitrogen cycling. Männikjärve bog has one of the longest water table records in the boreal zone, continuously monitored since 1956. Common uncertainties encountered while working with peatland trees (e.g. narrow, missing and wedging rings) were in our case exacerbated with difficulties related to the instability of the relationship between tree growth and peatland environment. We hypothesized that the instable relationship was mainly due to a significant change of the limiting factor, i.e. the rise of the water table level due to human activity. To test our hypothesis we had to use several novel methods of tree-ring chronology analysis as well as to test explicitly whether undetected missing rings biased our results. Since the hypothesis that the instable relationship between tree growth and environment was caused by a change in limiting factor could not be rejected, we proceeded to find possible significant changes of past water table levels using structural analysis of the tree-ring chronologies. Our main conclusions were that peatland pines can be proxies to water table levels and that there were several shifting periods of high and low water table levels in the past 200 years.
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Affiliation(s)
- Marko Smiljanić
- Institute for Botany and Landscape Ecology, University of Greifswald, Soldmannstrasse 15, 17487, Germany.
| | - Jeong-Wook Seo
- Institute for Botany and Landscape Ecology, University of Greifswald, Soldmannstrasse 15, 17487, Germany
| | - Alar Läänelaid
- Department of Geography, Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise St. 46, 51014 Tartu, Estonia
| | | | - Branko Stajić
- Faculty of Forestry, University of Belgrade, Kneza Viseslava 1, 11000 Belgrade, Serbia
| | - Martin Wilmking
- Institute for Botany and Landscape Ecology, University of Greifswald, Soldmannstrasse 15, 17487, Germany
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112
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Sjögersten S, Black CR, Evers S, Hoyos-Santillan J, Wright EL, Turner BL. Tropical wetlands: A missing link in the global carbon cycle? GLOBAL BIOGEOCHEMICAL CYCLES 2014; 28:1371-1386. [PMID: 26074666 PMCID: PMC4461074 DOI: 10.1002/2014gb004844] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 10/04/2014] [Indexed: 05/26/2023]
Abstract
Tropical wetlands are not included in Earth system models, despite being an important source of methane (CH4) and contributing a large fraction of carbon dioxide (CO2) emissions from land use, land use change, and forestry in the tropics. This review identifies a remarkable lack of data on the carbon balance and gas fluxes from undisturbed tropical wetlands, which limits the ability of global change models to make accurate predictions about future climate. We show that the available data on in situ carbon gas fluxes in undisturbed forested tropical wetlands indicate marked spatial and temporal variability in CO2 and CH4 emissions, with exceptionally large fluxes in Southeast Asia and the Neotropics. By upscaling short-term measurements, we calculate that approximately 90 ± 77 Tg CH4 year-1 and 4540 ± 1480 Tg CO2 year-1 are released from tropical wetlands globally. CH4 fluxes are greater from mineral than organic soils, whereas CO2 fluxes do not differ between soil types. The high CO2 and CH4 emissions are mirrored by high rates of net primary productivity and litter decay. Net ecosystem productivity was estimated to be greater in peat-forming wetlands than on mineral soils, but the available data are insufficient to construct reliable carbon balances or estimate gas fluxes at regional scales. We conclude that there is an urgent need for systematic data on carbon dynamics in tropical wetlands to provide a robust understanding of how they differ from well-studied northern wetlands and allow incorporation of tropical wetlands into global climate change models.
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Affiliation(s)
| | - Colin R Black
- School of Biosciences, University of NottinghamNottingham, UK
| | - Stephanie Evers
- School of Biosciences, University of NottinghamKuala Lumpur, Malaysia
| | | | - Emma L Wright
- School of Biosciences, University of NottinghamNottingham, UK
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