The Change of Undergrowth,Soil Microorganism, Enzyme Activity and Nutrient in Different Developing Stage of the Chinese Fir Plantation

With the reduction of undergrowth coverage in Chinese fir plantation from juvenile to mideum plantation,the amount of soil microorganism,bacteria,fungi,actinomycetes and the soil enzyme activity especially the proteinase,phosphorylase,sucrase and the organic nutrient content cut down rapidly.With the increase of undergrowth coverage in Chinese fir plantation from mideum to mature plantation,the amount of soil microorganism,bacteria and the soil enzyme activity especially the proteinase,phosphorylase,sucrase and the organic nutrient content went up gradually.Due to the reduction of phosphorylase and hydrogen peroxidase causing the accumulation of poison as phenolic compounds in the soil of medium plantation.Maybe this is one of the causes for the yield reduction or low survival rate in successive rotation of Chinese fir.