Soil microbial diversity and litter decomposition increase along a forest recovery gradient in tropical montane forests of Malaysian Borneo

Logging and forest conversion are occurring at alarming rates in the tropical forests. These disturbances alter soil chemistry and microbial diversity, and disrupt carbon cycling through shifts in litter decomposition. Direct links between microbial diversity and soil properties such as pH are well established; however, the indirect impacts of logging and forest conversion on microbial diversity and litter decomposition are poorly understood. We investigated how soil properties and soil functions change across a forest recovery gradient in the tropical montane forests of Malaysian Borneo. We used surface (top 5 cm) soil to assess soil physicochemical properties, next-generation DNA sequencing to assess soil microbial diversity, and standardized litterbags to assess litter decomposition and stabilization. Our results show that soils of the older forests harbored significantly greater microbial diversity, decomposed litter faster, and stabilized greater amounts of litter than soils of the younger forests and converted sites. These results suggest that logging and forest conversion significantly affect soil microbial diversity and can have lasting effects on carbon cycling in tropical montane forests.