Soil Microbial Activity And Community Functional Diversity In Eucalyptus Plantation

Soil microbe is the main undertaker of the decomposition of organic matter, the species composition and activity directly affect the material cycle of forest and nutrient supply,and reflect the soil fertility and quality changes.Because of Eucalyptus Plantation afforestation was digging and and frequent tending after intense (fertilizer, weeding and so on), changes in the original soil structure and environment, may cause soil microbial community structure and functional changes, effects on soil nutrient balance. To investigate the effects of different stand age of Eucalyptus Plantation on soil microbial activity and community functional diversity,used static alkali absorption to soil respiration for a year observation in2,3and5years old Eucalyptus Plantation and mangium×A.auriculaef,Cunninghamia lanceolata and Pinus massoniana, used fumigation and BIOLOG respectively study on soil microbial biomass and soil microbial community function diversity in above forests, Obtained the following main progress:(1) Eucalyptus near-mature forest soil respiration rate was significantly higher than that of mangium×A.auriculaef,Cunninghamia lanceolata and Pinus massoniana, and Eucalyptus young forest is low, Eucalyptus plantation speed up soil organic matter turnover rate, the main cause of fluctuations is fertilization, litter decomposition, vigorous growth of Eucalyptus, soil water and heat condition. Six types of forest soil respiration showed evident seasonal variation of eucalyptus trees,3years and5years unripe eucalyptus forest soil respiration rate is higher than2year old eucalyptus forest, the different artificial forest soil respiration rate is difference. Influential factors on soil respiration of soil temperature and soil moisture content, the two can work together to explain the variation of soil respiration of58%～75%. Eucalyptus forest soil respiration rate of soil temperature with high sensitivity, compare with eucalyptus forests, mangium×A.auriculaef, Cunninghamia lanceolata and Pinus massoniana forest soil respiration rate of soil temperature sensitivity is not high.(2) Eucalyptus afforestation significantly increase soil microbial biomass, soil nutrient supply capacity is higher than that of mangium×A.auriculaef, Cunninghamia lanceolata and Pinus massoniana, Eucalyptus fertilization, litter and hydrothermal environment conducive to microbial growth. Six kinds of forest soil microbial biomass content of large difference, and soil organic carbon, total nitrogen, available nitrogen and phosphorus have obvious correlation. Eucalyptus trees and soil microbial biomass content is relatively high, soil microbial biomass carbon, nitrogen, phosphorus content of5year old eucalyptus trees is highest, and then is3year old eucalyptus forest,2years old is minimum. Compared with eucalyptus, mangium×A.auriculaef,Cunninghamia lanceolata and Pinus massoniana forest, soil microbial biomass is lower. (3) Eucalyptus afforestation significantly improve soil microbial community functional diversity and organic matter transformation function, eucalyptus trees and soil microbial diversity index increased with age in different stand age of Eucalyptus, and the structure of soil microbial biomass carbon metabolic functional group is similarity. The AWCD of using single carbon source for soil microbial community in6kinds of stands increased with time, the ability to using carbon source for soil microbial community in6kinds of stands was similar. Eucalyptus forest on soil microbial community diversity index of Simpson, Shannon-Wiener and Shannon evenness were as5years old>3years old>2years old. Which, mangium×A. auriculaef,forest Simpson diversity index is higher than that of Eucalyptus forest, Shannon-Wiener diversity index and Shannon evenness index were higher for Eucalyptus forest than that of mangium×A. auriculaef,Cunninghamia lanceolata and Pinus massoniana. Sugars, amino acids, polymers, carboxylic acids and aromatic and other5kinds of carbon sources on6kinds of forest soil microbial community have a greater impact. In different types of carbon source utilization process,3kinds of eucalyptus trees between soil microbial communities exhibit similar carbon metabolic functional group structure, and other forest are different. Which, besides Simpson diversity index of Cunninghamia lanceolata showed higher than Eucalyptus plantation, Shannon-Wiener diversity index and Shannon evenness index of Eucalyptus plantation both showed higher than mangium×A.auriculaef,Cunninghamia lanceolata and Pinus massoniana. Carbohydrates, amino acids, polymers, carboxylic acids and aromatics of five kinds of carbon source for soil microbial community in6kinds of stands had greater effect. In the use of different carbon sources, soil microbial community in3kinds of Eucalyptus plantation showed similar of carbon metabolism functional group structure, and compared with other stands was different.