机构地区:[1]Rubenstein School of Environment and Natural Resources,University of Vermont,Burlington VT 05405(USA) [2]Ecology&Evolutionary Biology,University of Tennessee,Knoxville TN 37996(USA) [3]The Gund Institute for Environment,University of Vermont,Burlington VT 05405(USA) [4]Department of Biology,University of South Alabama,Mobile AL 36688(USA) [5]Climate Change Science Institute and Environmental Sciences Division,Oak Ridge National Laboratory,Oak Ridge TN 37830(USA) [6]Institute for Environmental Genomics&Department of Microbiology and Plant Biology,University of Oklahoma,Norman OK 73019(USA) [7]The Department of Physical Geography and Ecosystem Science,Lund University,Lund 22362(Sweden)
出 处:《Pedosphere》2020年第1期135-145,共11页土壤圈(英文版)
基 金:the United States Department of Energy,Office of Science,Office of Biological and Environmental Research,Terrestrial Ecosystem Sciences Program(No.DE-SC0010562).
摘 要:Northern peatlands store nearly one-third of terrestrial carbon(C)stocks while covering only 3%of the global landmass;nevertheless,the drivers of C cycling in these often-waterlogged ecosystems are different from those that control C dynamics in upland forested soils.To explore how multiple abiotic and biotic characteristics of bogs interact to shape microbial activity in a northern,forested bog,we added a labile C tracer(13C-labeled starch)to in situ peat mesocosms and correlated heterotrophic respiration with natural variation in several microbial predictor variables,such as enzyme activity and microbial biomass,as well as with a suite of abiotic variables and proximity to vascular plants aboveground.We found that peat moisture content was positively correlated with respiration and microbial activity,even when moisture levels exceeded total saturation,suggesting that access to organic matter substrates in drier environments may be limiting for microbial activity.Proximity to black spruce trees decreased total and labile heterotrophic respiration.This negative relationship may reflect the influence of tree evapotranspiration and peat shading effects;i.e.,microbial activity may decline as peat dries and cools near trees.Here,we isolated the response of heterotrophic respiration to explore the variation in,and interactions among,multiple abiotic and biotic drivers that influence microbial activity.This approach allowed us to reveal the relative influence of individual drivers on C respiration in these globally important C sinks.Northern peatlands store nearly one-third of terrestrial carbon(C) stocks while covering only 3% of the global landmass; nevertheless, the drivers of C cycling in these often-waterlogged ecosystems are different from those that control C dynamics in upland forested soils. To explore how multiple abiotic and biotic characteristics of bogs interact to shape microbial activity in a northern,forested bog, we added a labile C tracer(13C-labeled starch) to in situ peat mesocosms and correlated heterotrophic respiration with natural variation in several microbial predictor variables, such as enzyme activity and microbial biomass, as well as with a suite of abiotic variables and proximity to vascular plants aboveground. We found that peat moisture content was positively correlated with respiration and microbial activity, even when moisture levels exceeded total saturation, suggesting that access to organic matter substrates in drier environments may be limiting for microbial activity. Proximity to black spruce trees decreased total and labile heterotrophic respiration. This negative relationship may reflect the influence of tree evapotranspiration and peat shading effects; i.e.,microbial activity may decline as peat dries and cools near trees. Here, we isolated the response of heterotrophic respiration to explore the variation in, and interactions among, multiple abiotic and biotic drivers that influence microbial activity. This approach allowed us to reveal the relative influence of individual drivers on C respiration in these globally important C sinks.
关 键 词:CARBON cycling enzyme activity HETEROTROPHIC RESPIRATION labile CARBON RESPIRATION ombrotrophic BOG PEAT moisture plant proximity soil CARBON SINK
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