Microarray-based analysis of changes in diversity of microbial genes involved in organic carbon decomposition following land use/cover changes

To increase our understanding of the impact of land use/cover changes on soil microbial decomposition genes involved in organic carbon decomposition, we analyzed soil samples in four sites with different land cover/use histories in a subalpine region of western Sichuan. One site was in a primitive Abies faxoniana forest, the second and the third sites were spruce plantations established in 1960's and 1980's, respectively, and the fourth site was in a cropland dating back to 1960's. The genomic DNA from the microbial community was isolated and hybridized against a functional gene microarray containing 1,961 probes. There were 39, 62, 41, and 28 gene probes with statistically significant positive signals and the gene diversity index (H') values were 3.59, 4.04, 3.70 and 3.16 in primitive forest, spruce plantations established in 1960s and 1980s and cropland, respectively. The results suggested that the number of functional genes and the gene diversity index were correlated with increasing amounts of soil organic carbon, except in the primitive Abies faxoniana forest site. cluster analysis demonstrated that primitive forest soil was clustered more closely to soil from the spruce plantation established in 1960s.