The Dynamic Study On Soil Microoganism And Enzyme Activity In Economic-forest Transformation Pattern Of Low-beneficial Cypress Forest

In recent years, due to the environmental destruction and the interference of human activity, the area of low-efficiency forest is increasing, which have caught the attention of domestic and foreign experts and scholors. Deyang is the upper region of Yangtze River. Transforming the low-efficiency forest and improving the effectiveness of soil and water conservation is the essential part for the Yangtze River shelterbelt construction and one of the key research of topics "The technology to optimize structure and enhance function of planted forest ecosystem in Sichuan hilly area". In this paper, the low-beneficial cypress forest in Deyang city Jingyang District is used as contrast. In the early stage of economic-forest transformation especially Chinese pricklyash, soil microorganism and soil enzyme activities and nutrient content of plots are studied by field investigations and laboratory analysis. The relationship amongst soil microbial population,enzyme activities and soil nutrient content,and the changes of soil quality are researched in ord to provide the theoretical base for the economic transformation model of low-efficiency forest.Main conclusions are as follows:1.Soil pH value in pepper transformation model is lower than the contrast and the difference are significant. The content of soil total K, available K and available P under the economic-forest transformation model are pole significantly higher than that under the inbeneficial cypress forest. The variance of other nutrients are not significant. The content of soil organic matter and soil nutrients have no significant differences in pepper plot and walnut plot. The vertical distribution of every soil nutrient content is the same, that soil nutrient content is gradually decreased with soil depth.2.The proportion of bacteria in total number more than 75%, described as the most important status in soil microorganism. The actinomycetes take the second place and the fungi is the least. Compared with the inefficient cypress forest, soil microorganisms in economic-forest transformation models are increased. The quantity of soil microorganism mainly distributed in surface layer. Its vertical distribution is uniform, that is the number decrease rapidly with soil depth. As a whole, the microbial population in the summer and autumn are more than in the spring and winter. The number of bacteria in pepper plot, walnut plot and control plot is the most in the winter. And the bacteria in pepper plot and control plot is minimum in the winter, while the bacteria in walnut is minimum in the spring.The number of actinomycete in pepper plot and control plot is at most in autumn and at least in winter, while walnut plot’s actinomycete number is maximum in summer and minimum in spring. The quantity of soil fungi in two economic-forest transformation patterns and control plot are the most in the autumn, but the number in pepper plot and walnut plot are at least in spring with at least in winter in control plot.The seasonal dynamic rule of the amount of total microorganism consistents with bacteria.3.The difference of the soil catalase activity and urease activity are not significant between walnut plot and control plot,but the phosphatase activity in walnut is significantly lower than control plot.All the three kinds of soil enzyme activity have no significantly difference between pepper plot and control plot.With the increase of soil depth, the three kinds of enzyme activity show weaken and its activites are mainly concentrated in the surface layer.The soil catalase activity in the economic-forest transformation patterns and controlled woodland are the highest in the summer, but the former is the lowest in the winter,while the latter is the lowest in the spring.The urease activity in the pepper plot is the highest in the summer and lowest in the winter,but the urease activity in the walnut plot and control plot is the highest in the autumn and the lowest in the winter. The soil phosphatase activity in all the plots is the highest in the summer and the lowest in the winter.4.In the short term, inorganic fertilizercan not effect the content of organic matter significantly. The content of total N, hydrolyable N and available p increase with raising inorganic fertilizer, and the content of soil total P, total K, available K rise in the first stage and then decrease. The number of soil bacteria increases firstly and then decreases with the rising of nitrogenous fertilizer. Asmall amount of phosphorus,potassium fertilizer can improve the number of bacteria,but excessive fertilizer can inhibit bacteria activity. The number of soil actinomycetes and fungi will decrease with the application of inorganic fertilizer. In the short time,application of inorganic fertilizer can increase the soil enzyme activities significantly, but the excessive application of inorganic fertilizer can reduce the enzyme activities.5.The amount of bacteria is negatively related to thecontent of available P significantly, and is positively related to the content of available K pole significantly. The number of actinomycete and total P, total N, hydrolyable N has significant or extremely significant positively correlation. The variance level between fungi number and organic matter, total N, hydrolyable N, availiable P achive significant or extremely signicant.Soil catalase activity is extremely significantly correlated with total N. Soil urease activity and total N, available K content is significantly related. And the variance level between Phosphatase activity and total P, availiable P, total N, hydrolyable N, availiable K all achieved significant or extremely significant. The number of bacteria, actinomycete, and three kinds of enzyme activity are significant or extremely significant positive correlation. The number of fungi is associated with phosphatase activity significantly and catalase activity significantly.6.1n the economic transformation forest, the correlation of the content of soil total N and the number of actinomycete and fungi and enzyme activity is most significant, that the content of soil total N have a greater influence on the soil biological properties. Fungi quantity and phosphatase activity and most soil nutrient significantly or extremely significantly correlated, which show that the number of fungi and phosphatase activity can better evaluate the soil fertility level.