Abstract:

This study was carried out to evaluate the effect of rocky desertification on genetic diversity of shrubby grassland soil bacteria. Soil samples of four different degrees of rocky desertification shrubby grasslands were collected in the restoration and treatment point of Puding County, Guizhou Province, and soil sample of corn planting sites in rock cracks was also collected as control. The treatments were as follows:potential (A), slight (B), medium (C), severe rocky desertification (D) and the control (E). The soil bacterial community structure was studied using denatured gradient gel electrophoresis (DGGE) analysis. The results showed that the complexity and richness of bacterial communities showed a declining trend with the aggravation of desertification, and the Shannon-Wiener and richness index of the soil sample A were higher than that of B, C, D. But the ShannonRocky desertification; Shrubby grasslands; Soil bacteria; Genetic diversityWiener, Evenness and Richness index of the control (E) were the lowest. It showed that the complexity and richness of soil bacteria significantly decreased after soil cultivation. Clustering analysis showed that they were divided into two clusters in the phylogenetic tree:the one cluster was the control (E) and the others were A, B, C, D. Among them, A and B had high degree of similarity, and the C and D had the maximum similarity. The phylogenetic analyses showed that the 13 sequenced fragments were clustered into 10 branches, and the soil bacteria in different degrees of rocky desertification shrubby grasslands soil had different community structures and had high degree of genetic diversity.

Key words: Rocky desertification, Shrubby grasslands, Soil bacteria, Genetic diversity

摘要：

为探讨石漠化对灌丛草地土壤细菌遗传多样性的影响，在贵州省普定县石漠化治理区采集潜在（A）、轻度（B）、中度（C）和重度石漠化（D）4种不同类型的灌丛草地土样，并以石缝玉米耕作地为对照（E），应用PCR-DGGE技术对土壤细菌群落结构进行了研究。结果表明：样地A的香农指数与丰富度指数均高于样地B，C，D，说明随着石漠化的加剧，细菌群落的复杂度与丰富度呈下降趋势，而对照组（E）最低，这表明耕作后土壤中细菌的复杂度与丰富度显著下降。通过聚类分析发现对照组E为一个族，A，B，C，D为一个大族，其中样地A与B，样地C与D土壤细菌PCR-DGGE图谱相似度较高。在系统发育树分析中发现13个序列片段聚成了10个分支，土壤细菌在不同程度石漠化灌丛草地土壤中会形成不同的群落结构，并具高度的遗传多样性。

关键词: 石漠化, 灌丛草地, 土壤细菌, 遗传多样性