Scale- and location-specific multivariate controls of topsoil organic carbon density depend on landform heterogeneity

[Display omitted] •Wavelet used to identify soil organic carbon density (SOCD) variations and controls.•Controls of the significant variations in SOCD differed with landform heterogeneity.•Soil moisture dominated SOCD variations at large scales at more homogenous landform.•More variables needed to explain SOCD variations at more heterogeneous landforms.•A new index developed to identify the best factors for explaining SOCD variations. Spatial variability of surface soil organic carbon density (SOCD) and its controls may be scale-specific and localized depending on the landforms which drive distribution of environmental factors such as soil moisture and soil texture. We hypothesize that SOCD variation dominates at larger scales and is controlled by less number of environmental variables at more homogeneous landforms. The objective of this study was to test this hypothesis by revealing the scale-location specific multivariate relationships between surface SOCD and environmental factors at three transects (i.e., upstream, midstream, and downstream) with different landform heterogeneities in a typical basin using bivariate wavelet coherency and multiple wavelet coherence. Results indicated that variations in SOCD was dominated at large scales (>10.6 km) across the entire transect (i.e., global) at the more homogeneous midstream transect, while those were more localized and mainly occurred at small (