Study On Soil And Water Conservation Effect Of Different Stands In Sandshale Red Soil Area Of HengDong

Hunan vigorously develops the construction of soil and water conservation forest in the soil and water conservation development strategy.But because of lacking of the understanding of different plant growth rule, genetic features and its growth soil and climate environment, It leads some soil and water conservation forest fail to adapt to the tree and soil,and leads the forest loss function of soil and water conservation.By studying the soil and water conservation effect between different type forests in sandstone and shale red soil region in HengDong, we can know the growth characteristics of different type forests and the planting and configuration mode between different tree species,it can provide data support for the governance of the soil and water loss problem in research area.On this basis, this study combined with general science and technology project of water resources bureau of Hunan province-"soil and water conservation biological regulatory mechanism research in typical red soil hilly region",take three representative different kinds of soil and water conservation forest of sand shale in the red soil region in HengDong as the research object,combine with the forest type and the Environmental characteristics,adopt field investigation and indoor experiment analysis method.combined with those indicators to analysis the moisture effect and woodland soil maintain effect in the layer of different forest,build index system and use the principal component analysis (PCA) to evaluate the soil and water conservation effect in three different type forests,the results are as follows:(1) Holding water effect of the forest canopy and the vegetation layer in Pinus elliottii - Koelreuteria elegans mixed forest performs the best. The maximum water-holding capacity of the plant layer in three types forest is 80.79 t/hm2 to 88.39 t/hm2, and the value is 7.25～7.93 times than that of the control slope.(2) The water-holding capacity of litter layer in Cinnamomum camphora (L.) Presl - Liquidambar formosana Hance mixed forest is the best, followed by Pinusm assoniana -Cinnamomum camphora (L.) Presl mixed forest, and the Pinus elliottii-Koelreuteria elegans mixed forest is the least.The litter storage of three types forest is 3.84 t/hm2～5.42 t/hm2,the total maximum water-holding capacity is 3.15t/hm2～ 6.39t/hm2,the water absorbing capacity and immersion time shows a logarithmic relationship,from the point of bibulous rate, Cinnamomum camphora (L.) Presl Liquidambar formosana Hance mixed forest performs better.(3) The trend of the water-holding capacity in the soil layer is Pinusm assoniana-Cinnamomum camphora (L.) Presl mixed forest> Cinnamomum camphora (L.) Presl-Liquidambar formosana Hance mixed forest> Pinus elliottii-Koelreuteria elegans mixed forest.The maximum water-holding capacity in the soil layer is between 1063.31 t/hm2 and 1106.89 t/hm2,capillary water-holding capacity is between 883.74 t/hm2 and 967.21 t/hm2, the minimum water-holding capacity is between 844.96 t/hm2 and 920.38 t/hm2,the maximum water-holding capacity,capillary water-holding capacity,the minimum water-holding capacity is 15.99%,14.26% and 21.62% bigger than that of the slope soil which is developed from the same parent rock respectively.(4) From the point of the soil erosion resistance index, in 0-20cm layer, Cinnamomum camphora (L.) Presl -Liquidambar formosana Hance mixed forest performs the best, followed by Pinusm assoniana-Cinnamomum camphora (L.) Presl mixed forest, and Pinus elliottii-Koelreuteria elegans mixed forest performs the worst.The soil aggregate account for 94.46～97.58% of the soil sample;Resistance index is between 0.3263 and 0.2945; Water stability index is between 0.7503 and 0.8353; The permeability coefficient is between 3.973 and 4.358.(5) The trend of the annual surface runoff and the surface erosion sediment loads is Pinusm assoniana -Cinnamomum camphora (L.) Presl mixed forest> Pinus elliottii-Koelreuteria elegans mixed forest> Cinnamomum camphora (L.) Presl-Liquidambar formosana Hance mixed forest.In summary, under the condition of same rainfall, the annual sediment yield and surface runoff in Cinnamomum camphora (L.) Presl - Liquidambar formosana Hance mixed forests is the lowest,so the water and soil conservation effect of which is the best.(6) Use principal component analysis to analyze the research indicator which are extracted from three different types forests, the comprehensive evaluation results of the effect of the soil and water conservation is Cinnamomum camphora (L.) Presl - Liquidambar formosana Hance mixed forest is the best (0.5234),the next is Pinusm assoniana-Cinnamomum camphora (L.) Presl mixed forest (0.3206),Pinus elliottii-Koelreuteria elegans mixed forest is the lowest (-0.844);The trend of the soil and water conservation effect is Cinnamomum camphora (L.) Presl Liquidambar formosana Hance mixed forest> Pinusm assoniana-Cinnamomum camphora (L.) Presl mixed forest> Pinus elliottii-Koelreuteria elegans mixed forest.