CHARACTERISTICS OF RHIZOSPHERE AND BULK SOIL MICROBIAL COMMUNITIES IN RUBBER PLANTATIONS IN HAINAN ISLAND, CHINA

Abstract

Phospholipid fatty acid analysis was used to investigate spatial variations in microbial communities of rhizosphere and bulk soil in rubber plantations in Hainan Island. Rhizosphere and bulk soil were collected from immature and mature rubber trees in areas with four different soil parent material types. For each site, total microbial biomass and biomass of bacteria, fungi, actinomycetes and ratio of fungi to bacteria in rhizosphere were significantly higher than those in bulk soil. The rhizosphere/bulk soil ratio for fungi in soil derived from basalt ranged from 10.44 to 12.33, which were significantly higher than those in soil derived from granitic gneiss, shallow marine deposits and granite (2.22–6.00). Total microbial biomass and bacterial biomass were positively correlated with soil organic carbon and total N in both rhizosphere and bulk soil. Total microbial biomass and biomass of bacteria, fungi and actinomycetes were correlated with soil total P in the rhizosphere. Rhizosphere total microbial biomass decreased in soil derived from basalt and increased in soil derived from shallow marine deposits with increasing age of rubber trees. The main factor affecting the composition of microbial communities in bulk and rhizosphere soil was soil parent material.