Simultaneous Estimation of Actual Litter Enzymatic Catalysis and Respiration Rates with a Simple Model of C Dynamics in Sphagnum-Dominated Peatlands

摘要

C dynamics in soils plays an important role in the interactions between climate and terrestrial ecosystems. Given the importance of the soil C pool in future climate scenarios, accurate models that can then be integrated into global models are required. On the one hand, models of soil C dynamics can be very simplistic in that only solid organic matter (OM) is taken into account with constant rates. Such models can miss important features of soil C dynamics such as enzymatic activity and CO2 production. On the other hand, some models are too complicated to be experimentally calibrated, tested, and widely used. We propose a model of soil C dynamics that (i) integrates all C fluxes from the solid to the gaseous form, and (ii) can be easily implemented experimentally. Because peatlands are important C stores that are experiencing vegetation changes, the model was tested on experimental results obtained with peatland litter: Sphagnum cuspidatum (autochtonous vegetation), Molinia caerulea, and Betula spp. (both invasive species). Our model was able to accurately describe the early stages of C dynamics in litter especially when only one pool of OM was used and when catalysis and respiration rates were allowed to decrease with time. Our model is efficient in assessing the entire actual catalysis rate. This is a notable achievement as usually, enzyme activity is measured on specific enzymes in conditions often far from actual ones. Our model appeared to be sufficiently robust and worthy of development, keeping in mind that it should remain experimentally testable.