| Caohai is the special plateau wetland in China.The existence of Caohai not only maintains the ecological balance of this area,but also plays a big role in ensuring economic development.However,because the natives are lack of awareness to protect the vegetation around the Caohai,which has caused the improper exploition of Caohai and severe damage to the ecological environment in the area,especially the ecological conditions for vegetation growth.With the environment in typical karst plateau wetland as research background,this research selected several representative land use types of the wetland in Caohai Basin,Guizhou Karst Plateau as the research object.Compared and analyzed the different in economic functions of soil between various land use types and farmlands or grassland formed by abandoned cultivation.Understanded the impact of different land-use types on soil,water conditions during the process of plant management and whether plantation had played a role in improving soil ecology during the process of the plant management on karst plateau wetlands.It also explored the specific performance of improving soil ecology,revealed the mechanism of improving soil ecology of different land use types during the process of plant management,while provided basic research data for the restoration and reconstruction on the degraded ecosystem of karst plateau wetland and the sustainability of social-economic development.In this study,by comparing different land use types with grassland,it is found that different land use types have improved soil bulk density and porosity compared with grassland in Caohai basin except Cunninghamia lanceolata forest and arable land.The interaction between land use type and soil depth on total soil porosity,soil mass water content,capillary water capacity,maximum water capacity,maximum water storage capacity and existing water storage capacity.With the increase of soil depth,the bulk density of each sample increases.The transformation of land use type has the function of reducing soil bulk density and improving soil structure.The ranking of soil total porosity,soil saturated water holding capacity and capillary water holding capacity can be seen that the other land use types except Cunninghamia lanceolata forest,Camellia sinensis forest and arable land have improved their total soil porosity compared with grassland.In this study,the principal component analysis was carried out on 12 indexes of soil bulk density,soil total porosity,soil capillary porosity,soil mass water content,saturated water holding capacity,capillary water holding capacity,maximum water storage capacity,existing water storage capacity,soil initial seepage rate,soil steady seepage rate,average permeability rate and total permeability.It can be found that the average score of soil water conservation function of different land use types is ranked,except for Cunninghamia lanceolata(-3.63),arable land(-4.97)is lower than grassland(-3.53),the other land use types are higher than grassland.According to the comprehensive score of 0-20 cm surface soil by coordinate comprehensive evaluation method,the score of other land use types except arable land is larger than that of grassland,which indicates that the improvement of soil nutrients is beneficial to the change of land use type.Soil SOC content of Populus yunnanensis forest and Koelreuteria paniculata-Populus yunnanensis-Cupressus funebris mixed forest decreased first and then increased with the increase of soil depth,Among them,the difference of SOC content in different soil layers of Pinus armandii forest is the largest.average soil TN?TP?TK content of Camellia sinensis forest is the highest,and the total soil nutrient content in the study area is in the middle and low level.TN?TP?TK?AN?AP?AK content of all plots except tillage There are all types of soil outside the ground,and the surface soil is superior to the middle and deep soil.there are significant differences between C:N?C:K?C:P?N:P between different land use types of soils,and with the increase of soil depth,the stoichiometric ratio tends to decrease,indicating that with the increase of soil depth C?N?P the difference of elements gradually decreases.soil SOC content was significantly correlated with soil bulk density,total porosity,capillary porosity and TN?TP?AK content(P<0.01),indicating that the addition of organic matter plays an important role in the formation of soil structure,and N and C elements are closely related in the accumulation and storage process.C?N?P accumulation cycle is closely related in the study area.The improvement of soil bulk density and pore condition is helpful to improve soil nutrient conditionThe results show that the soil erosion resistance index decreases with the increase of time and tends to be stable.With the increase of time,the impact resistance coefficient of soil of different land-use types increased gradually,and the growth rate of Koelreuteria paniculata-Populus yunnanensis-Cupressus funebris mixed forest was the fastest.By linear fitting of impulse resistance coefficient and time of different land use types,it is found that binomial fitting is optimal,and the R~2of function fitting is 0.88 Therefore,it is considered that it can best reflect the relationship between soil impact coefficient and time change in different land use types.This study is mainly aimed at considering the difference of soil ecological effect of different land use types in Caohai basin,so we select more mature,representative index and more perfect evaluation index system.Environmental factors,soil physical properties and soil chemical properties were selected as indicators for comprehensive evaluation of soil ecological benefits.According to the principal component of soil ecological benefit and the index SEB soil ecological benefit of different land use types in Caohai basin,it is concluded that the three types with better land use types in Caohai basin are Pinus yunnanensis forest,Koelreuteria paniculata-Populus yunnanensis-Cupressus funebris mixed forest and Populus yunnanensis forest. |
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