Correlations between topography and topsoil chemical properties across different parent materials in evergreen broadleaf forests of Taiwan

Context Topography regulates surface water flow, which in turn alters the horizontal spatial distribution of soil chemical properties. Nevertheless, it remains uncertain whether the influence of topography on soil chemistry is consistent under different parent material conditions. Aims This study aimed to clarify whether (1) soil chemical properties differ and (2) the topographic variables that influence their spatial distribution vary, across the two plots with different parent material conditions. Methods We compared various soil chemical properties, including soil pH and concentrations of total carbon (TC), total nitrogen (TN), phosphorus, potassium, calcium, magnesium, iron, copper, manganese, and zinc, across different topographic conditions in two Taiwanese forest dynamics plots: the Kenting karst forest dynamics plot, a tropical forest on limestone; and the Lienhuachih forest dynamics plot, a subtropical forest on quartzose and feldspathic sandstone. Key results The results showed that while parent material properties exerted a significant effect on soil chemistry, common spatial distributions were still observed. The TC and TN were primarily concentrated on ridges and upper slopes (which generally have lower topographic wetness index), while most other chemical elements (except iron) were correlated with relatively drier topographic conditions. Conclusions Topography was an important driver of the spatial distribution of some soil chemical properties, especially TC and TN, across the two plots with different parent material conditions. Implications These findings provide a better understanding of how topography influences the spatial distribution of soil chemical properties in these broadleaf forests and offer useful baseline information for future forest ecology and management.