Influence of the microtopography of patagonian peatbogs on the fluxes of greenhouse gasses and dissolved carbon in porewater

Abstract

Peatlands play an important role in global carbon cycling, as they act as a natural sink of carbon dioxide (CO2) or as a source of methane (CH4). The influence of microtopography (lawns and hummock-hollow complexes) in the biogeochemical dynamics of dissolved organic and inorganic carbon (DOC and DIC) and dissolved CH4 and CO2 is generally miss-considered. Southernmost Patagonia has huge areas of pristine peatlands, which are still in a largely natural state with scarce anthropogenic influence. In this study we provide foundational insights into the dynamics of greenhouse gasses (GHGs) and DOC in Sphagnum dominated peatlands of Southern Patagonia, assessing the impact of microtopography on these dynamics. The stocks of dissolved GHGs and DOC in hummock-hollows complex and lawns were analysed at three depths (25, 50, and 75 cm) in four ombrotrophic peatbogs. CH4, N2O and CO2 fluxes, net ecosystem exchange (NEE) and gross primary productivity (GPP) were also studied. CO2 and CH4 fluxes were strongly affected by microtopography. Hummock-hollows showed higher CO2 fluxes, and temperature and radiation were the main drivers for respiration and GPP, respectively. In addition, in this microtopography, higher DOC concentrations were observed at the top depth. In contrast, lawns acted as a source of CH4, with higher emission rates and high dissolved GHGs concentration throughout the depth profile.