Soil-Plant Nutrients And Biodiversity Of Soil And Water Conservation Forests In Simian Mountain Of Chongqing

The serious soil erosion,which leads to soil nutrients loss,is considered as one of the main forms of non-point source pollution.Soil and water conservation forests are established to conserve soil and water,and control the non-point source pollution.It is of importance and difficulty in the discipline of soil and water conservation to study the tree species selection and configuration patterns for soil and water conservation forest.In order to understand the protection effect and biodiversity of different forests for water and soil conservation and their configuration patterns on soil nutrients,soil and plant nutrients and biodiversity of these forests in the district of low mountains and hills in Simian Mountain of Chongqing in the Three Gorges,were studied in different periods by applying descriptive statistical analysis,correlation analysis,principal component analysis and analysis of variance.The results showed as follows:1) The organic matter content,total N,available P and readily available K concentration was 57.32g/kg,1.92g/kg,8.57mg/kg,and 96.36 mg/kg,respectively,in the study area of Simian Mountain in Chongqing.The soil pH was 4.77,and it was strong acid soil.2) There were significant differences of soil nutrients among bare land,plantations and natural forests,in the order of natural forests＞plantations for water and soil conservation＞bare land. In natural forest and plantation sample plots,the organic matter content,total N,available P and readily available K concentration was 82.61g/kg,2.81g/kg,8.86mg/kg,120.91mg/kg and 59.80g/kg,2.14g/kg,8.43mg/kg,98.81mg/kg,respectively,which increased by 231.08%, 212.06%,11.77%,84.39%and 139.67%,138.12%,6.32%,50.69%accordingly when compared with those in bare land.3) A significant effect of forest age on soil nutrients was found.Compared with 5-year-old plantations,the nutrients concentrations in the first principal component in the 10-year-old plantations increased 127.59%.When compared with the bare land,the organic matter content, total N,available P and readily available K concentration in the 10-year-old plantations and 5-year-old plantations increased 202.47%,265.01%,10.06%,76.22%and 125.12%,75.39%, 3.46%,42.14%,respectively.The 10-year-old plantations were the rival of the natural forests for soil nutrients protection.However,there were no significant differences between different configuration patterns of the same age forests for water and soil conservation on soil nutrients, including 4 plantations of different configuration patterns and 3 natural secondary forests.4) There were different species diversities for 5 plantations,in the order of Liquidambar formosana Hance×Schima superba Gardn.et Champ×Lithocarpus glabra×Cinnamomum camphora Presl＞Lithocarpus glabra×Schima superba Gardn.et Champ＞Cunninghamia lanceolata Hook×Pinus masfsoniana Lamb×Schima superba Gardn.et Champ＞Cunninghamia lanceolata Hook×Pinus masfsoniana Lamb＞Cunninghamia lanceolata Hook.The species diversity of Lithocarpus glabra×Schima superba Gardn.et Champ mixed forest was the highest in shrub layer,and that of Cunninghamia lanceolata Hook forest was the highest in herb layer.5) In tree and shrub layers,there was no significant correlation between species diversities and soil nutrients.But there was significant correlation between them in the herb layer.The higher soil nutrients concentrations,the greater the species diversity was.6) The total N,total P and total K concentrations of Cinnamomum camphora Presl's and Cunninghamia lanceolata(Lamb.) Hook.'s leaves of unit volume were the highest among the 6 different species.Their bioaccumulation factors(BF) were the highest as well,which were 18.99 and 17.49,respectively.