Study On Community And Genetic Diversity Of Soil Bacteria Under Phyllostachy Pubescens Stands By PCR-DGGE

Mao bamboo (phyllostachy pubescens) is one of the major forest resourses in southern China. It has been widely developed by replacing natural forest since its high economic, social and ecological benefits. Biodiversity of plant was decreasing when bamboo replacing natural forest, especially when bamboo was managed intensively. The plant richness could be down to zero when practice of fertilization and weeds cleaning was conducted. It was proved that biodiversity of under ground system has an important role in keeping ecological stability and sustainable development of land. The objective of this paper is to reveal the evolution of soil bacteria community under bamboo stands by DGGE of 16S rDNA V3 fragment polymerase chain reaction products. The following are the main results from this study.(1) Soil bacteria communities appeared no great change with growing time of bamboo when traditional practice with no fertilization but only weeds cutting in winter was undertaken. However, dominant species has shifted from some to other. It can be inferred from the bacteria community of soil since the year of 1960 bamboo bacteria community that bacteria communities would change with the time of pure bamboo plantation.(2) Soil bacteria communities in the area of Tianmu Mountain National Natural Reserve are of rich biodiversity, and no great change was observed with the invasion process of bamboo into natural forest but each type of the forests has its own characteristic species that was not dominant. Shannon indexes from DGGE slices showed no significant difference among the various types of vegetations when bamboo invaded into natural needle forest, however, Shannon index of soil bacteria in bamboo stands was greater than those in broad-leaved forest and the transition zone with mixture bamboo and broad-leaved forest. The evidence from sequence of recovered DNA slices showed that soil bacteria were mainly classified as Proteobacterium, Firmicutes, Acidobacteria and Actinobacterium. Most species of soil bacteria in this study found in GeneBank database were uncultured.(3) Intensive management generally did not cause great change in soil bacteria communities but some species declined in population and even disappeared. Soil bacteria communities were observed no difference between bulk and rhizosphere. The activity of bamboo roots affected bacteria population greatly.(4) The microcosmos experiment by adding different rate of bamboo leaf into broad-leaved forest showed that in soil bacteria communities were affected more by incubation time than treatments with different rate of bamboo leaf. The richness of soil bacteria communities was decreasing with incubation time, the original soil has the highest Shannon index (2.564) and soils after 52 weeks incubation has the lowest one (1.934).In conclusion, soil bacteria communities in different bamboo systems are generally stable. The type of vegetation and time of intensive management would further the effect on soil bacteria communities and richness in long future.