| Taking the Yangou watershed located at hilly-gully region of the Loess Plateau as an example,the responses of soil organic carbon,total nitrogen and enzymatic activity on abandoned lands to vegetation restoration were studied.The results showed that with an increase of vegetation restoration years,change tendency of vegetation coverage,vegetation abundance,and amount of species was increasing in the beginning of vegetagion restoration(4～16 years),then decreasing(16～29 years or 16～55 years),and later increasing again(after 29 years or 55 years).Compared to cropland,topsoil(0～20 cm) organic carbon,total nitrogen,invertase activity,urease activity,and alkaline phosphatase activity significantly increased with an increase of vegetation restoration years,but change of soil catalase activity with an increase of vegetation restoration years was not obvious.Compared to the cropland,topsoil organic carbon,total nitrogen,invertase activity,urease activity,and alkaline phosphatase activity increased by 35%～184.6%,5.7%～157.4%,89.6%～566%,32.9%～331.2%,and 0.18%～184.8%,respectively.The responses of topsoil organic carbon and urease activity to vegetation restoration were that in the beginning of vegetation restoration(0～8 years),both of them increased with an increase of vegetation restoration years;during 8～29 years of vegetation restoration,both of them decreased with an increase of vegetation restoration years;after 29 years of vegetation restoration,both of them increased again with an increase of vegetation restoration years.The responses of topsoil total nitrogen,invertase activity,and alkaline phosphatase activity to vegetation restoration were that in the beginning stage of vegetation restoration(0～16 years),three of them increased with an increase of vegetation restoration years;during 16～29 years of vegetation restoration,three of them decreased with an increase of vegetation restoration years,and after 29 years of vegetation restoration,three of them increased again with an increas of vegetation restoration years.Topsoil invertase activity,urease activity,and alkaline phosphatase activity were significantly correlated with soil organic carbon and total nitrogen,but the relationship between topsoil catalase activity and soil organic carbon,and topsoil catalase activity and soil total nitrogen were not significant. |