Effects Of Thinning On Enzyme Activity And Nutrition In The Soils Of Planted Stands Of Oriental Arborvitae And Chinese Pine

As the forestation program accomplished in Beijing, the next work is how to manage the established forests well. As we know, soil is the main source of material and energy. It is a very essential way to keep and enhance the soil fertility in order to improve the forest quality. In this paper, Platycladus Orientalis and Pinus tabulaeformis carr in Beijing mountainous area were experimented in the index of soil alkali phosphatase activity, urease activity, catalase activity, total N, available phosphorus available potassium and organic matter and the data was analysed by principal component analysis. We expect to achieve a better thinning intensity from the view of soil enzyme and nutrient. The result shows:1. In the sunny slope with thick-layer soil oriental arborvitae plantation, different thinning intensity had significant effect on the activity of soil phosphatase, urease and catalase, and the influence of the medium thinning was great, but the heavy tending got the hightest of total N, available potassium and organic matter.The principal component analysis showed that the rank of the treatments was medium>heavy>light>control.2. In the shady slope with thick-layer soil oriental arborvitae plantation, different thinning intensity had significant effect on the activity of soil phosphatase, urease and catalase, and the trend is differ with the treatment. The soil nutrient was increased by the treatments ,as the principal component analysis showed:heavy>light>medium>control in the depth of 0-10cm, while the rank is light>medium>heavy>control in the depth of 10-20cm.3. In the sunny slope with thin-layer soil oriental arborvitae plantation, the activity of soil phosphatase, urease and catalase all lower than the control.The pH value were enhanced as the intensity increased. Soil nutrient had different variety as the intensity changed, the principal component analysis showed that the rank of the treatments was heavy > control >medium >light in the depth of0-10cm, while the rank is medium> control > heavy>light in the depth of 10-20cm. 4. In the sunny slope with thin-layer soil Chinese pine plantation, the activity of soil phosphatase, urease and catalase all lower than the control, but there were no significant difference between them. The enzyme activity increased with the augment of intensity of thinning. The principal component analysis showed that the rank of the treatments was medium >heavy > control > light in the depth of 0-10cm, while the rank is control > medium> heavy>light in the depth of 10-20cm.