Study On The Relationship Between Soil Physical And Chemical Properties And Soil Water Conservation Function Of Chinese Fir Forest

Chinese fir, was one of the important timber trees in China, widely distributed in the South area. It could not only provide the material for our country’s economic construction, but also could play an important role in the ecological benefits, especially in the function of water conservation. Sources of water have become one of the most prominent problems in many countries and regions, especially in many large cities under today’s ecological environmental crisis. Exploring the Chinese fir forest’s water conservation was not only cardinal significance to the Fushou forestry, but also for the whole South of Chinese.Based on the young growth, mid-maturation forest and near-mature forest of Chinese fir as the research object of Fushou forestry centre, at the same time based on the near natural forest experimental area as experimental plot, to research the difference of soil physical properties, chemical properties of soil and soil water conservation function between the three different kinds of forest age fir and nearly natural forest. This paper researches the relationship between the forest soil physical and chemical properties and soil water conservation function of Fushou forestry centre, achieves the goal of improving soil water conservation function through taking the soil physical and chemical measures, and improves the theoretical basis and practical reference value of the soil water conservation function of the area. The main research conclusion of this article is as follows:(1) The size of volume weight of soil in three different kinds of forest age fir and nearly natural forest are as followings:Chinese fir mid-maturation forest (1.44g/cm3)>Chinese fir near-mature forest (1.37g/cm3)>Chinese fir young forest (1.30g/cm3)>near natural forest (1.22g/cm3). The near natural forest soil porosity (67.88%) is bigger than the three different kinds of forest age fir, and the largest is in the topsoil. The air permeability and water permeability of near natural forest soil are better than the three different forest age fir.(2) Soil organic matter content is as followings:near natural forest (56.63g/kg)>Chinese fir young forest (37.08g/kg)>Chinese fir mid-maturation forest (30.05 g/kg)>Chinese fir near-mature forest (25.10g/kg). The total N and total P content of near natural forest soil is significantly higher than the different age of fir (p <0.05), but the total soil K content of natural forest’s is under the different age of fir (p<0.05). With the increase of plantation age of Chinese fir, the soil nutrient content reduces. In addition to the soil total N and total P content, the soil total K content of three different Chinese fir plantation age has significant difference (p<0.05). The soil’s PH value in this region is acidity (4.5～6.5), the soil PH value of near natural forest is markedly lower than the three difference age of Chinese fir, and the change of PH value is not obvious along with the increasing of soil thickness (p<0.05). With the increase of soil thickness, the soil PH value of near nature forest increases.(3) Near natural forest has the good function of soil water conservation, seen from the water storage capacity of saturated soil, it’s size as following:near natural forest (2000.4t·hm-2)>Chinese fir near-mature forest (1498.4t·hm-2)>Chinese fir young forest(1400.5t·m-2)>Chinese fir mid-maturation forest(1326.9t·hm-2); Seen from the water storage capacity of non capillary, as following:near natural forest (1104.8t·hm-2)>Chinese fir near-mature forest (1077.4t·hm-2)>Chinese fir mid-maturation forest (812.4t·hm-2)> Chinese fir young forest (574.3t·hm-2); Seen from the water storage capacity of capillary, as following:near natural forest (895.5t·hm-2)>Chinese fir young forest (826.1t·hm-2)>Chinese fir mid-maturation forest(514.5t·hm-2)>Chinese fir near-mature forest(421.0t·hm-2).(4) Through analysing the correlation of the physical and chemical properties of soil and the function of soil water conservation,we can found that the soil bulk density, noncapillary poropsity, capillary porosity, organic matter and total P content had extremely significant correlation with the function of soil water conservation (P<0.01); but the total N content and PH value had medium strong correlation significantly with the function of soil water conservation (p<0.05). Through multiple regression analysis,we established regression equation, and it regards soil bulk density (Xi), capillary porosity (X2), the capillary porosity (X3), total N content (X4) and PH (Xg) as the independent variables, soil water conservation quantity as the dependent variable:Y=2.197X1+1.487X2+2.868X3-2.147X4-1.806X8, the adjusted R2=0.783.(5) According to the research results and the field survey, this study targeted put forward soil physical and chemical measures, such as,taking artificial overall in the study area, trees cover, building mixed forest and return to take leftovers soil and so on. In order to improve the function of soil water conservation in the study area.