Soil weathering regime regulates tree-throw effects on carbon and nitrogen dynamics in temperate forests

Our research focus and novelty: Tree-throw disturbances in temperate forests can affect 60-90% of forest floors over centennial to millennial timescales creating mound and pit microsites. It is assumed that these microsites drive soil organic carbon (SOC) and total nitrogen (TN) dynamics in tree-thrown sites; however, their effects have not been fully quantified against environmental factors like soil geochemistry, weathering intensity, and depth gradients. The current study addresses a fundamental question in forest soil ecology (how disturbance-created landforms (mound-pit microsites) interact with pedogenic weathering regimes to control C and N distribution across landscapes). Our study design: We sampled 42 dated mound-pit pairs selected from a wider network of 229 dated tree-throw sites (using dendrochronology and radiometric techniques), covering 30 to 6,000 years in age; we compared three temperate forests along a soil weathering gradient: Haplic Cambisols (Razula, Czech Republic), Entic Podzols (Žofín, Czech Republic), and Albic Podzols (Michigan, USA). We analyzed 520 soil samples across five depth intervals and three microsite positions to characterize SOC, TN, and pedogenic metal forms (Fe, Mn, Al).