Study On The Soil Conservation Function Of Pinus Yunnanensis Forest In Central Yunnan Plateau

Forest ecosystem has the function of soil conservation,as the main forestvegetation types in Yunnan Province, studying the Pinus yunnanensis forest soilconservation function, has very important scientific research and practicalsignificance.This paper uses the method of the combination of field investigation，sampling and laboratory analysis， Pinus yunnanensis forests in Jianshan smallwatershed and in the Mopan Mountain National Forest Park in Yuxi city, YunnanProvince are selected respectively as the research object, has carried on the quantitativeresearch of Pinus yunnanensis forest soil conservation function from two aspects of soilreinforcement and fertility maintenance functions.The specific results are as follows:（1）Soil and water conservation benefits of Pinus yunnanensis forest1) Compared with the control, the runoff reduction rates of shrub-grass land andsecondary forest were91.87%and91.61%, while the rate of plantation was77.45%.Sediment reduction rates of shrub-grass land, secondary forest and plantation were99.17%,98.76%and96.45%.2) The runoff from May to October was more than83percent of the annual totalrunoff, and the sediment loss was more than90%of the annual total sediment loss.3) Compared with the control, soil TOCs and CPIs of plantation, shrub-grass landand secondary forest increased by42.27%to108.19%and55.53%to145.27%.4) Correlation analysis results showed that: the soil and water conservation ofvegetation had an effect on soil carbon stock, and there was an extremely significantpositive correlation among the water storage efficiency and soil carbon stock.Compared with the control, shrub-grass land and secondary forest had greatefficiencies of water storage. Shrub-grass land, secondary forest and plantation had greateffects on reduction of sediment with a descendant order. From May to October is thekey period for the prevention and control of soil and water erosion. All of three differentvegetation have the functions to increase soil carbon stock. Effective water storageefficiency can significantly increase soil organic matter content。（2）Study on soil physical and chemical properties of Pinus yunnanensis forest1) Compared with the plantation at20years, soil physical and chemical properties of secondary forest were significantly superior.2) Middle-aged secondary forest had the smallest soil bulk density and largest soilnatural water content.3) The soil pH value of Pinus yunnanensis forests at different ages were stronglyacidic. Middle-aged secondary forest had the highest soil total nitrogen content,hydrolyzable nitrogen content, total phosphorus content, fast-acting potassium contentand soil organic matter in the0-20cm soil layer. The total potassium contents in the0-20cm soil layer were similar in three types of secondary forest, but the middle-agedsecondary forest in the20-60cm soil layer had the tallest total potassium content.4) There was an extremely significant negative correlation among pH value, soilorganic carbon, total nitrogen, hydrolyzable nitrogen, total phosphorus and totalpotassium content; while an extremely significant positive correlation among soil organiccarbon, total nitrogen, hydrolyzable nitrogen, total phosphorus fast-acting potassiumand total potassium content.Showed that in the sustainable management and local management process ofyunnan pine forest, should give priority to middle-aged secondary forest, at the sametime use the relation between the soil physical and chemical properties to optimize themanagement.