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Ecoenzymatic stoichiometry and microbial processing of organic matter in northern bogs and fens reveals a common P limitation among peatland types
Citation:
Hill, B., C. Elonen, T. Jicha, R. Kolka, L. Lehto, S. Sebestyen, AND L. Seifert-Monson. Ecoenzymatic stoichiometry and microbial processing of organic matter in northern bogs and fens reveals a common P limitation among peatland types. BIOGEOCHEMISTRY. Springer, New York, NY, 120(1):203-224, (2014).
Impact/Purpose:
Our objectives for this study were to 1) investigate the role of microbial ecoenzymes in facilitating organic matter processing in northern peatlands; 2) to determine the relative C, N, and P limitations on microbial processes and organic matter decomposition; and 3) to consider the environmental constraints on microbial EEA processes. We also use the ecoenzyme model to explore potential climate change impacts on organic matter decomposition in peatlands.
Description:
We compared C, N, and P concentrations in atmospheric deposition, runoff, and soil standing stocks with microbial respiration (DHA) and ecoenzyme activity (EEA) in an ombrotrophic bog (S2) and a minerotrophic fen (S3) to investigate the environmental drivers of biogeochemical cycling in peatlands at the Marcell Experimental Forest in northern Minnesota, USA. Ecoenzymatic stoichiometry was used to construct models for carbon use efficiency (CUE) and decomposition (M), and these were used to model respiration (Rm). Our goals were to determine the relative C, N, and P limitations on microbial processes and organic matter decomposition; and to identify environmental constraints on ecoenzymatic processes. Atmospheric inputs to the two study watersheds were monitored at an adjacent NADP monitoring station. Mean annual water, C, and P yields were greater in the S3, while N yields were similar in both S2 and S3. Soil chemistry differed between S2 and S3, and both watersheds exhibited significant soil horizon effects for all variables. DHA and EEA differed by watersheds and soil horizons; CUE, M, and Rm differed only by soil horizons. C, N, or P limitations indicated by EEA stoichiometry were confirmed with orthogonal regressions of ecoenzyme pairs and enzyme vector analyses, and indicated greater N and P limitation in S2 than in S3. Ecoenzymatic stoichiometry, microbial respiration, and organic matter decomposition were responsive to resource availability and the environmental drivers of microbial metabolism, including those related to global climate changes.
