Topography determines soil C:N:P stoichiometry more than forest attributes in heterogeneous subtropical karst forests

• Topography dominates soil N and P stoichiometry in karst forests. • Variation in soil C:N:P ratios is primarily attributed to elevation and rock exposure. • Forest attributes exert only a weak regulatory influence on soil C:N:P stoichiometry. • Findings aid forest management and restoration in karst regions. Understanding the ecological stoichiometry of soil nutrients and their drivers is essential for managing forest ecosystems, particularly in highly heterogeneous landscapes, such as karst forests. However, the effects of topography and forest attributes on soil carbon (C), nitrogen (N), and phosphorus (P) stoichiometry in these ecosystems remain unclear. This study investigated the influence of topographic conditions and forest attributes on the contents and stoichiometric ratios of C, N, and P in the surface soils (0–10 cm) of species-rich subtropical karst forests in China. The results showed that topography dominated the variability in total nitrogen (TN) and total phosphorus (TP) contents and their stoichiometry. TN and TP increased by 0.51% and 0.97%, respectively, per 1% increase in rock exposure rate (RER), but decreased by 0.46% and 1.79% per 1-m rise in elevation (ELE). In contrast, the C:N, C:P, and N:P ratios exhibited opposite trends. The soil organic carbon (SOC) was not significantly affected by topography. Forest attributes showed limited influence, explaining only 6.02% of the total variance in soil C:N:P stoichiometry. SOC and TN increased with the nearest taxon index (NTI), while the C:N and C:P ratios declined with the Shannon–Wiener diversity index. Correlation analyses revealed significant associations among topographic variables (ELE, RER, and aspect), forest attributes (Pielou’s evenness, NTI, and mean DBH), and soil C:N:P stoichiometry. The redundancy analysis revealed that topography accounted for a greater proportion of the variance (35.21%) than forest attributes (6.02%), with ELE, RER, and slope contributing 19.22%, 10.98%, and 3.18%, respectively. These findings highlight that topographic conditions rather than forest characteristics are the primary drivers of soil C:N:P stoichiometric patterns in heterogeneous karst forests. This information is critical for guiding effective forest management and restoration strategies in karst regions.