Research On Microorganism Changes Under The Transformation From Tropical Rain Forests To Rubber Plantations

Tropical rain forest has the most abundant species diversity on land. But a series of eco-problems have been caused by large area of rubber plantation. Through collecting of 10 a, 20 a and 30 a soil profiles of rubber plantations, ravine seasonal rain forests and lower hill seasonal rain forests, the analyses showed that, soil microbial diversity and community structure changed in the process of the transformation from Xishuangbanna tropical rain forests to rubber plantations based on the technique of Illumina MiSeq. The result indicated that:The transformation from tropical rainforest to rubber caused significant changes in natural water content, bulk density, total porosity, available phosphorus(AP), total nitrogen(TN), available postassium(AK), total postassium(TK) and pH value. Moreover, the soil physicochemical properties was changed significantly by the years of rubber planting after the tropical rain forest been destroyed. While both soil physicochemical properties and biodiversity index changed the most significantly in the sub-surface layer after the plant types have been changed.The indexes of soil microbial abundance Ace and Chao indicated that the highest soil microorganism abundance was 20-year rubber plantation while the lower hill rain forest was the lowest. However the samples from different sites showed the same rustles that the highest soil microbial abundance was surface layer followed by bottom layer and sub-surface lay. Cluster analysis shows that the microbial community structure was similar in the sub-surface layer and bottom layer but different in the surface layer. RDA indicated that 3 environmental factors which effected the microbial community structure was AK, TK and water content with the contribution rate of 83%.Acidobacteria(44.67%) was still the dominant species and Proteobacteria(13.92%), Chloroflexi(13.13%), Verrucomicrobia(9.99%) and Planctomycetes(5.23%) made up the majority(86%) of soil microbial communities. Heatmap, RDA and PCA results showed that soil microbial communities of all sites was different while LRF was the most different site.