Soil Microbial Communities in Natural and Managed Cloud Montane Forests

Forest management often results in changes in soil microbial communities. To understand how forest management can change microbial communities, we studied soil microbial abundance and community structure in a natural Chamaecyparis (NCP) forest, a disturbed Chamaecyparis (DCP) forest, a secondary (regenerated) Chamaecyparis (SCP) forest and a secondary (reforested) Cryptomeria (SCD) forest. We analyzed soil microbial abundance by measuring phospholipid fatty acids (PLFAs) and microbial community structure by denaturing gradient gel electrophoresis (DGGE) in the studied forest soils. The content of the soil PLFA fungal biomarker decreased from NCP to SCP, DCP and SCD forest soils, associated with the degree of disturbance of forest management. The ratio of soil Gram positive-to-negative bacteria and the stress index (16:1ω7t to 16:1ω7c) increased from NCP to SCP and DCP soils; thus, disturbed forests except for SCD showed increased soil microbial stress. Principal component analysis of soil microbial groups by PLFAs separated the four forest soils into three clusters: NCP, DCP and SCP, and SCD soil. The DGGE analysis showed no difference in the microbial community structure for NCP, DCP and SCP soils, but the community structure differed between SCD and the three other forest soils. In cloud montane forests, disturbance due to forest management had only a slight influence on the soil microbial community, whereas reforestation with different species largely changed the soil microbial community structure.