The Characteristics of Soil Microbial Functional Diversity of Six Types of Vegetation in Tropical Regions

PurposeTo study the characteristics of the soil microbial community structure of typical vegetation types in the tropical region of Hainan, and reveal the effects of vegetation characteristics and soil physical and chemical characteristics on the soil microbial community.

MethodUsing BIOLOG-ECO technology, the functional diversity of soil microbes in six typical vegetation types in the tropical region of Hainan was studied.

ResultsThe average well color development (AWCD) curve changes of soil microorganisms of different vegetation types were basically the same, but the carbon source utilization capacity were different. As the AWCD value in 192 hours for analysis, the order of the soil AWCD of different vegetation types was: mixed forest>semi-mangrove forest>secondary forest>Cocos nucifera forest>Pinus elliottii×P. caribaea forest>Casuarina equisetifolia forest. There were differences in the utilization rates of the six main types of carbon sources for different forest stand types. The utilization rates of carbohydrates, amino acids, and polymers by mixed forest, semi-mangrove, secondary forest, and C.nucifera forest were highest. However, the utilization rates of these six carbon source substrates by soil microorganisms in the planted pure forests of C. japonica and P. chinensis were not high. Among them, amino acids and carboxylic acid carbon sources were the main carbon source utilization forms of the two artificial pure forests. The soil microbial McIntosh index, Shannon-Wiener index, Simpson index and Pielou index of different vegetations also showed a trend that mixed forests, semi-mangroves, and secondary forests were higher than pure forests. Principal component analysis showed that the metabolic diversity of soil microbial communities in different vegetation types could be significant among them, PC1 could explain 47.32% of the variance of all variables, PC2 could explain 31.58% of the variance of all variables, and the cumulative contribution could reach 78.90%. The correlation analysis showed that the relationship between each index of soil microbial community diversity and soil organic carbon and total nitrogen extremely significant positive correlation (P<0.01), negative correlation with soil pH, and significantly positive correlation with soil water content (P<0.05).

ConclusionCompared with pure forest, artificial mixed forest plays an important role in improving the characteristics of soil microbial community.