Tree species effects on soil enzyme activities through effects on soil physicochemical and microbial properties in a tropical montane forest on Mt. Kinabalu, Borneo

Tree species influence on the soil mineralization process can regulate overall nutrient cycling in a forest ecosystem, which may occur through their effects on substrate quality, soil physicochemical properties and soil microbial community. We investigated tree species effects on soil enzyme activities in a tropical montane forest on Mt. Kinabalu, Borneo. Specifically, we analyzed C- and P-degrading enzyme activities, as well as the relationships among the enzyme activities, soil physicochemical properties, substrate quality (C, N, and P concentrations), and microbial composition in the top 5 cm soils beneath conifers (Dacrycarpus imbricatus and Dacrydium gracilis) and broadleaves (Lithocarpus clementianus, Palaquium rioence, and Tristaniopsis clementis). Activities of acid phosphatase and β-d-glucosidase were significantly different among the tree species. Soil moisture, total C and N content and microbial lipid abundance (a proxy for microbial composition) could influence the enzyme activities although the relative contributions of microbial composition to the enzyme activities might be smaller. A higher acid phosphatase activity beneath Dacrydium than those beneath the other tree species can compensate for a lower concentration of P in available fractions beneath Dacrydium. This localized mineralization activity could subsequently influence soil nutrient availability in this forest.