| Seceting soil quality change with vegetation restoration in Yangou catchment located at hilly-gully region of the Loess Plateau as research site, vegetation restoration effects on soil physical, chemical and microbial properties in recent 100 years were studied by using field survey and experimental analysis. Soil quality indices were selected by correlation and principal component analysis, and soil quality index (SQI) was calculated. The rearch results strengthen knowledge for understading interaction between vegetation restoration and soil quality. The main research results were summarized as follows:1)During vegetation restoration, the evolution of plant community groups in Yangou catchment was: Setaris viridis + Artemisia scoparia + Corispermum chinganicum Iljin (4 years) - Artemisia gmelini + Thermopsis lanceolata(8 years) - Artemisia gmelini + Stipa bungeana + Bothriochloa ischaemun (16 years) - Artemisia gmelini + Periploca sepium Bunge (29 years) - Sophora davidii + Periploca sepium Bunge (55 years) - Pyrus betulaefolia (100 years). For the first 16 years after restoration, species abundance increased, then decreased up to 55 years, and finally increased again.2)Vegetation restoration greatly improved soil physical properties such as soil water field capacity and soil aggregate stability. With an increase in vegetation restoration year, soil water field capacity in 0-20cm soil layer increased by 16.74% to 43.41%, compared with cropland (control). After 55 years of vegetation restoration, >0.25mm soil water-stability aggregate in 0-20cm soil layer increased by 66.31% compared with cropland for the modifed Yoder's method. MWD increased from 0.65mm after 4 years of restoration to 2.41mm after 100 years. LB slow wetting was more sensitive in representing soil aggregate stability compared with modified Yoder's, LB fast wetting and LB stirring methods.3)With the years of vegetation restoration, soil organic carbon, total nitrogen, alkaline nitrogen, alkaline phosphatase, urease, and invertase activity increased continuously. In soil profile, soil organic carbon, total nitrogen, alkaline nitrogen, available nitrogen, alkaline phosphatase activity, urease, and invertase activity in 0-5 cm depth of soil profile were greatly higher than that in other layers of soil profile. Soil nutrient content and enzyme activity in 5-10 cm and 10-20 cm depths were not obviously different, but soil nutrient content and enzyme activity in 5-20 cm depth were much higher than those in 10-20 cm depth.4)Fungi amount, respiration rate, microbial biomass C, microbial biomass N and microbial biomass P increased with the age of vegetation restoration. In soil profiles, they were higher in 0-5 cm layer of soil profile, which was similar trend with soil nutrients and enzymetic activity.5)Soil organic carbon, total nitrogen and alkaline nitrogen were highly correlated. Available phosphorus showed significant linear correlation with total porosity. There was a very significant linear correlation between organic carbon and alkaline phosphatase, urease, invertase activity respiration rate and microbial biomass N, P. They were also correlated with total nitrogen. Respiration rate and microbial biomass P were very significant correlated to alkaline nitrogen. Alkaline phosphatase, invertase activity and microbial N were significant correlated with alkaline nitrogen. There was a very significant linear correlation between microbial biomass C and N which was similar with microbial N and P.6)By applying correlation analysis and principal components analysis, 6 sensitive factors of soil quality were selected as soil quality indicators, they were: soil organic carbon, alkaline nitrogen, slow wetting MWD, invertase activity, fungi and microbial biomass P. According to the calculating soil quality index for different vegetation restoration years, the results showed that soil quality at 100 years increased by 541% compared with cropland. Responses of soil quality to vegetation restoration can be divided into three stages: in the first stage (0-16 years), SQI increased quickly from 0.01 to 0.45; in the second stage (16-55 years), SQI kept almost stable from 0.45 to 0.47; in the third stage (55-100 years), SQI increased slowly from 0.47 to 0.73. |
PDF Full Text Request