Hillslope-induced environmental gradients regulate potential soil respiration in temperate peatlands

Along peatland catenas, micro- to meso-scale topographic variation shapes microclimate and biogeochemical properties, creating distinct environmental regimes. Yet, how such heterogeneity regulates soil respiration in peatlands has been much less studied. To this end, we sampled five slope positions along a peatland hillslope and combined microclimate monitoring with laboratory incubations and geochemical analyses. Specifically, we asked: (1) How do hillslope-induced environmental gradients influence spatial patterns of potential soil respiration (PSR) in temperate peatlands? and (2) How does PSR respond to increasing temperature? Results showed that soil biogeochemistry (i.e., soil pH, C/N ratio, soil organic matter (SOM) functional groups), PSR rates, and apparent temperature sensitivity (i.e., activation energy, Ea) varied substantially across hillslope positions and soil depths. We found that topographical and thermal-hydrological conditions are associated to soil biogeochemistry patterns across the landscape. The spatial heterogeneity in PSR and Ea was primarily explained by the functional group composition of SOM (45–68 % and 34 % in total, respectively), with cellulose and carboxylic acids accounting for 27 %–31 % of the variation in PSR rates, while aliphatic and lignin functional groups explained 13 % of the variation in Ea. In addition, the C/N ratio and pH together accounted for 13 %–26 % of PSR rate variation and 18 % of variation in Ea. This study demonstrates that hillslope topography-driven variations in soil biogeochemical properties strongly regulate potential peat soil respiration and its temperature sensitivity, providing mechanistic insights into peatland carbon–climate feedback and informing peatland management strategies.