Soil Biological Activity And Microbial Diversity Of Salinized Horqin Grassland

Salinization is one of importance factors on soil desertification, productivity and biodiversity of grassland. In the Horqin sandy land, a typical pastoral meadow of China, salinization has widely taken place, correspondingly resulting in the dramatic decrease of grassland productivity. In order to understand the effects of soil salinization on grassland soil properties, biological activities and biodiversity, degraded grassland with different salinization levels were selected as objects in this study. Based on field investigation and laboratory analysis, vegetation diversity and soil characteristics were analyzed in grassland. Furthermore, we adopted Biolog ECO microplate culture to learn the impact of soil salinization on functional diversity of soil microbial carbon source metabolism, as well as16S rDNA gene diversities of soil microbe via PCR-DGGE technique.The results showed that plant diversity, aboveground biomass, soil total nitrogen, available nitrogen, total phosphorus, potassium, organic matter and moisture content decreased significantly with the increase of salinization level. Soil microbial biomass C and N, and the activities of urease, protease, phosphomonoesterase, dehydrogenase, nitrate reductase and polyphenol oxidase decreased significantly as well. Significant differences of capacity, source, and type of carbon utilization in ECO microplate among the three grasslands were found (P<0.05). AWCD value of soil microbe changed with the different salinization levels, with the order as:light salinization> moderate salinization>heavy salinization, indicating that the function of soil microbial community was significantly affected by the salinization. Furthermore, with the increasing of salinization level,16S rDNA gene diversity index has an increase tread, while dominance index and evenness index did not change. The dominant species of the three grassland was almost the same. Acinetobacter, Pseudomonas, Moraxella nonliquefaciens are the dominant bacteria and widely distributed in the degraded grassland, and Bacillaceae is also one of dominant taxa in the heavy salinized grassland.