The effect of altitudinal gradient on soil microbial community activity and structure in moso bamboo plantations

Abstract

Moso bamboo (Phyllostachys edulis) is the fastest growing vegetation in the world, and it is widely distributed from low- to medium-elevation mountains in Taiwan. To understand how microbial activity and microbial community change with the elevation in bamboo plantations, we investigated soil microbial biomass, enzymes, and composition of bacteria and fungi in five moso bamboo plantations along an elevation gradient (600, 800, 1000, 1200 and 1400m asl) in central Taiwan. The soil microbial community structure was determined by analysis of the phospholipid-derived fatty acid (PLFA) and denaturing gradient gel electrophoresis (DGGE) profiles. The soil microbial biomass C (Cmic) and biomass N (Nmic) increased along the elevation gradient. Similarly, the activities of soil enzymes, such as cellulase, xylanase and urease, increased along the elevation gradient. The proportion of PLFAs that were attributed to total bacteria, Gram-positive (G+) bacteria, and Gram-negative (G-) bacteria also increased with the increase in elevation. However, the ratio of G+/G- bacteria decreased along the elevation increase, indicating that bamboo plantations at low elevations (600m, 800m and 1000m) contained less active soil organic matter than those at high elevations (1200m and 1400m). The results coincided with the availability of labile organic matter in bamboo plantation soils with lower Cmic/Corg and Nmic/Ntot in lower compared to higher elevations. Principle component analysis of PLFA content separated the low-elevation plantations from the high-elevation plantations. The DGGE analysis revealed that changes in both bacterial and fungal community structures were associated with the elevation gradient. Temperature changes along the elevation gradient contributed to variations in the soil microbial community in the bamboo plantations.