Southeast Asia experiences the highest relative rate of tropical deforestation in the world. In Malaysia, the majority of deforestation has been driven by the agricultural expansion of oil palm, Elaeis guineensis (Arecaceae) and logging. Both logging and oil palm agriculture alter soil physicochemical characteristics, which could cause shifts in microbial community composition and lead to changes in nutrient cycling. The aim of this study was to assess the impact of oil palm agriculture on tropical soil by comparing it to an old-growth, primary forest and a forest regenerating from logging. Soil cores were collected at the Pasoh Forest Reserve in Malaysia from three replicate plots at each site and divided into three depths: 0-2 cm, 2-10 cm, and 10- 20 cm. We quantified microbial biomass using phospholipid fatty acid analysis (PLFA) and analyzed fungal community composition using Illumina DNA sequencing.
Results/Conclusions
Microbial community composition was distinct across all sites and soil depths. However, microbial community composition in the logged forest was more similar to the primary forest than either forest community was to the oil palm site. Total microbial biomass was the lowest in the oil palm plantation, signifying that the soil ecosystem in oil palm plantations may experience altered carbon dynamics. We also found that total microbial biomass was the highest in the logged forest, possibly due to higher tree stem density in these areas. Numerous studies have documented the detrimental effects of oil palm agriculture on macroscopic taxa, but this is the first study explicitly examining soil microbial communities in these agricultural systems. These results have important implications for reclamation and management of forests and oil palm plantations in Southeast Asia.