Biotic and Abiotic Drivers of Peatland Growth and Microtopography: A Model Demonstration

Peatlands are important carbon reserves in terrestrial ecosystems. The microtopography of a peatland area has a strong influence on its carbon balance, determining carbon fluxes at a range of spatial scales. These patterned surfaces are very sensitive to changing climatic conditions. There are open research questions concerning the stability, behaviour and transformation of these microstructures, and the implications of these changes for the long-term accumulation of organic matter in peatlands. A simple two-dimensional peat microtopographical model was developed, which accounts for the effects of microtopographical variations and a dynamic water table on competitive interactions between peat-forming plants. In a case study of a subarctic mire in northern Sweden, we examined the consequences of such interactions on peat accumulation patterns and the transformation of microtopographical structure. The simulations demonstrate plausible interactions between peatland growth, water table position and microtopography, consistent with many observational studies, including an observed peat age profile from the study area. Our model also suggests that peatlands could exhibit alternative compositional and structural dynamics depending on the initial topographical and climatic conditions, and plant characteristics. Our model approach represents a step towards improved representation of peatland vegetation dynamics and net carbon balance in Earth system models, allowing their potentially important implications for regional and global carbon balances and biogeochemical and biophysical feedbacks to the atmosphere to be explored and quantified.