The Soil Quality Evaluation Of The Successive Chinese Fir And Chinese Fir—Masson Pine Rotational Plantation

Chinese fir is unique in the fast-growing commercial timber species in our country, which has good economic, ecological value and occupies an important position in our plantations. However, the research on the long-standing practice of forestry production is found that, with the planting generation of the fir increasing, the productivity of the land for artificial forest will be gradually declined, which seriously impacts on the sustainable high productivity yield and sustainable management of Chinese fir.For long time, the problem that planting Chinese fir continuously has caused the recession of soil fertility, has been paid great attention by many forestry workers, who create the mixed forest of the fir to restore and enhance the soil fertility of the woodland, Some academics have proposed for short-term rotation, such as planting one species of the legume, locust. However, these studies have focused on the study of fertility decline and recovery mechanism, and have been the lack of the different soil quality evaluation methods of Chinese fir cut-over land. In view of this, this paper takes the state-owned forest in the sub-dam building in Changting County even planted three generations of 3-year-old Chinese fir plantation (hereinafter referred to Chinese fir-Chinese fir replanting), the rotation of the 13-year Masson Pine plantation after 1 generation of the Chinese fir deforesting (hereinafter referred to the Chinese fir-pine) and after Chinese fir 1 generation deforesting and planting Masson Pine after 10 years to plant 3-year-old Chinese fir plantation (hereinafter referred to Chinese fir-pine -Chinese fir rotation) as the research object, on the basis of investigating the growth of Chinese fir plantation,It was selected three points in each plot,including the above slope, middle slope and lower slope.This was used to do the experiment were those soil samples for each slope position being selected a point and taken according to different layers A (0-20cm), B (20-40cm), C (40-60cm) from the bottom of the order.Being used the Chinese fir-pine soil quality deforestation as a control, and compare the two ways of the use of the land on soil quality about the three generations of 3-year-old Chinese fir plantation and fir 1 forest deforested to plant masson pine after 10 years, which lays the theoretical foundation to the land quality evaluation of Chinese fir forest, and maintain the long-term productivity and sustainable management of the Chinese fir plantation. The main results are as follows:1. The difference of soil physical properties in different land use patterns reached significant level, the condition of moistures under Chinese fir-Masson pine -Chinese fir rotation is relatively good than under Chinese fir-Chinese fir planted in the each layer of the above slope, such as the maximum water holding capacity of the 0-20cm,20-40cm soil layers in the above slope, compared with the control group, The soil maximum water holding capacity of Chinese fir-Chinese fir replanting are lower the 78.2g/kg,96.86g/kg, but the soil maximum water holding capacity of Chinese fir-Masson pine-Chinese fir rotation are higher 73.42g/kg,9.08g/kg; Capillary moisture and Minimum water holding capacity have this law. while each layer in the middle slope and lower slope has no obvious regularity.2. From the analysis on the chemical properties of the soil in different land use type, The differences of total nitrogen, total phosphorus, total potassium, available phosphorus content and pH value about the different layers in different depth of the Chinese fir-Chinese fir replanting and Chinese fir-pine-Chinese fir rotation have significantly different levels, while the differences of the available potassium content is not obvious. On the comparison of the soil fertility in different position of the above slope, the condition of soil fertility under the Chinese fir-Masson pine-Chinese fir rotation is relatively better than the soil under the Chinese fir-Chinese fir replanting, while different forest in different types and different soil layer have no obvious rule in the middle slope and lower slope. The total soil nitrogen as an example, from the total nitrogen content of the above slope comparison, compared with the control, both the total soil nitrogen content are lower, have shown a decreasing trend with the increase of soil depth. And in the middle slope and lower slope, Both of the total soil nitrogen content in each soil comparison show instability. Espacially in the middle slope,the total nitrogen content of Chinese fir-pine -Chinese fir rotation field is gradually decreasing trend with the increase of soil depth,and the total nitrogen content of Chinese fir-Chinese fir planted is began to decreased and then increased along with the increase of soil depth.3. This paper takes the above soil slope as an example, and evaluates the soil quality of Chinese fir -Chinese fir replanting and Chinese fir-Masson pine-Chinese fir rotation in the 0-20cm, 20-40cm,40-60cm layer by the principal component analysis. The analysis shows that soil moisture factors(Maximum water holding capacity, Capillary water holding capacity, Minimum water holding capacity), organic matter, total phosphorus, total nitrogen, and other factors can be used as the soil utilization evaluation index method of Chinese fir plantation. So,it uses these indicators to make use of a comprehensive evaluation for the soil quality of Chinese fir -Chinese fir replanting and Chinese fir-Masson pine-Chinese fir rotation.In the 0-20cm,20-40cm layer of the above soil slope,the score of soil quality about Chinese fir -Chinese fir replanting is relatively high than that of the comprehensive principal component of the soil quality of the Chinese fir-Chinese fir replanting, which is not significant in the 40-60 soil layer.Therefore, in the poor soil quality land, taking rotation of Chinese fir and Masson pine is a reliable land use patterns.