The Research On Soil Physico-chemical Properties And Water Source Conservation Function Fromdifferent Age Rubber Plantation In Xishuangbanna

Forest plays an important role in conserving water and fertilizers and it is important for us to explore the different forest vegetation communities in soil fertility and water conservation ability. Meanwhile, it is also a point to take some steps, including rational use of tropical soils to prevent existing forest soil degradation, adjusting the forest water environment, and getting a better understanding for the scientific management of water resources. The evaluation that different vegetation types conserve water and fertilize in the soil physical properties in Xishuangbanna can provide a scientific basis for vegetation management and water conservation management. Based on three different life cycle planting(i.e. rubber plantation, tea grove and secondary forest), we discussed the characteristics of soil and identified the effect of different environmental changes with the changing function, combined with mathematical statistics methods. We got the following conclusions:(1) The study area dominated by clay and silt, soils in the study area with viscous grain and silt based, the silt as the dominant particle size and sand content lower and soil types to silty sticky loam, silt loam based, followed by silty clay. Different types of forest vegetation, the grain size difference is also significantly different. In the rubber plantation, with the increase of planting time, soil clay particle group increase, corresponding to the silt and sand content reduced. Study area the average soil bulk density between 1.37g/cm~3~1.56g/cm~3. Each forest type, soil bulk density were decreased with soil depth increase showed a trend of increase, the tea trees of the soil bulk density was lower, may be associated with high soil organic matter and soil permeability. The maximum water holding capacity of different vegetation types was in the range of 3276.72 t/hm~2~4566.16 t/hm~2, and there was a great difference between the soil water holding capacity of different forest types, among which the maximum water holding capacity of the ancient tea forest was the highest.(2) Different kinds of forests showed varied soil chemistry features: the pH in study area vary from 4.245 to 5.425, thus the soil belongs to acid soil. It is easy to find that the soil pH show increased tendency with the growing age of rubber plantation; the organic matters in surface between 0 and 70 cm suggest the following declined features: ancient tea plantation>22a rubber plantation>secondary forest>10a rubber plantation>32a rubber plantation; Due to the different plantation, the nutrient matters of growing is different. The tea plantation possesses superior N content, and other plantation possesses little N concentration. As for the P, the tea plantation shows similar features. However, 20 a rubber plantation includes a lot of K content.(3) Based on the PCA analysis, we calculated the scores: ancient tea plantation(29.58)>secondary plantation(22.81)>32a rubber plantation(17.05)>22a rubber plantation(15.17)>10a rubber plantation(15.07). Additionally, the nutrient matter in ancient tea plantation is good, which is related with age, lush trees, fertile soil; however, different rubber plantations revel different nutrient status, the10 a rubber plantation is the most, and the 22 a and 32 a rubber plantation is relatively bad. These features show that a lot of nutrient matters are flowed with the growing age. In addition, the tapping also bring out a lot of nutrient matters, leading to the decline of soil fertile.(4) In this paper, the ideal point method is used to evaluate the water conservation capacity of different forest types. The results showed that the scores of different vegetation types were different:The ancient tea forest(0.147)>22a rubber forest(0.707) >secondary forest(0.839) >32a rubber forest(0.851) >10a rubber forest(0.942). Wherein, the water conservation capacity of ancient tea trees is high, the main reason is that with a higher degree of litter decomposition the surface soil is fertile, it is conducive to the growth of ancient tea trees. The hydrological function of the 22 a rubber plantation was the best. Secondly, it is the 32 a rubber plantation and 10 a rubber plantation. Water conservation function of the different age of the whole rubber trees had little difference. The 10 a rubber plantation at the young stage, the stand structure is single, the vegetation under the forest is less, water conservation capacity of the worst.32 a rubber forest is about to be renewed, the rubber forest consumes more soil nutrients, and the hydrological function is between the two types. The production of 22 a forest is richest, greatly influenced by artificial fertilization and management, which has the best water conservation function.