A simple dynamic equilibrium model shows that high phosphatase activity in tropical forest soils could be explained by rapid microbial turnover

Microorganisms and plant roots secrete phosphatase to obtain phosphorus (P) by degrading organic P. Previous studies have reported high phosphatase activity in tropical forest soils, which has been attributed to poor soil P conditions. However, rapid microbial turnover in tropical forest soils can also contribute to the high soil phosphatase activity. To test this, a simplified dynamic equilibrium model was developed. This model was intentionally designed to exclude the pathways of P originating from rock weathering or P adsorption by soils, with the aim of assessing the specific effect of accelerated microbial turnover on soil phosphatase activity. This model showed that accelerated microbial turnover consistently leads to elevated phosphatase activity, irrespective of the parameters, under the assumed environmental condition with the same litter P input. This suggests that rapid soil microbial turnover may serve as another crucial factor contributing to the high phosphatase activity in tropical forest soils, where both moisture and temperature are high.