Peatland Vegetation Patterns in a Long Term Global Change Experiment Find no Reflection in Belowground Extracellular Enz
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PEATLANDS
Peatland Vegetation Patterns in a Long Term Global Change Experiment Find no Reflection in Belowground Extracellular Enzyme Activities Magdalena M. Wiedermann 1
&
Mats B. Nilsson 2
Received: 19 May 2020 / Accepted: 2 September 2020 # Society of Wetland Scientists 2020
Abstract To assess the effects of global change on peatland vegetation and biogeochemistry we used a long term (21 years) in-situ plot scale manipulation experiment comprising nitrogen (N; ambient and 30 kg ha−1 yr−1), temperature (T; ambient and + 3.6 °C during growing season) and sulfur (S; ambient and 20 kg ha−1 yr−1) treatments in an oligotrophic boreal peatland. Vegetation was assessed by plant species cover estimates, while biogeochemical processes were characterized by measuring potential extracellular enzyme activity (EEA) of glucosidase, cellulase, aminopeptidase, phosphatase, and sulfatase in the peat matrix. We hypothesized that the plant communities would change in response to the N and T manipulations, and that belowground EEA would respond distinctively to the applied treatments as well as to changes in plant community. We found vascular plant cover to have strongly increased in the T treatment, whereas the Sphagnum cover collapsed in the high N treatment. Belowground we found enhanced enzymatic C and N acquisition activity in response to the N treatment, but EEA showed no response to the T treatment. No S effects were found, neither aboveground nor belowground. Contrary to our expectations, our data reveal a mismatch between above-ground vegetation patterns and belowground decomposition processes. In particular, the large increase in vascular plant cover in the warming treatment found no reflection in belowground EEA. Keywords Plant–soil (below-ground) interactions . Global change ecology . Ecosystem function . Ecophysiology . Extracellular enzymes . Enzyme stoichiometry . Plant functional types . Peat
Introduction Two global change factors with strong potential to alter peatland ecosystems are enhanced nitrogen (N) deposition and climate change (Limpens et al. 2008; Dise and Phoenix 2011). Over the last few decades, anthropogenic reactive nitrogen (Nr) production has been greater than production from all natural terrestrial systems combined (Galloway et al. Electronic supplementary material The online version of this article (https://doi.org/10.1007/s13157-020-01377-3) contains supplementary material, which is available to authorized users. * Magdalena M. Wiedermann [email protected] 1
Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA
2
Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
2008). The highest N deposition rates are measured in the northern hemisphere (Dentener et al. 2006; Reay et al. 2008; Bobbink et al. 2010), where peatlands form a dominant landscape element in boreal and sub-arctic areas. In these northern latitudes 95% of the global peat reserves are found, storing about 25% of the global soil carbon (C) pool (G
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