Abstract:

The soil enzyme activities and chemical properties were studied in five different land use types (i.e. woodland, grassland, abandoned land, farmland, and hydro-fluctuation belt) on riverbank slopes of the Three Gorges Reservoir. The results showed that the activity of soil catalase, urease and alkaline phosphatase in woodland was the lowest among all the land use types. In contrast, farmland had the lowest activity of the soil invertase and protease. However, abandoned land had the highest activity of the soil urease and protease, while grassland exhibited the highest activity of the soil invertase and alkaline phosphatase. Moreover, the soil catalase and alkaline phosphatase activity presented significantly positive relationship with content of soil total nitrogen, available nitrogen, total phosphorus, organic matter, and pH value, respectively. There was a significant negative correlation between alkaline phosphatase activity and soil available phosphorus content. The invertase and urease activity also showed a significant correlations with soil total nitrogen, available nitrogen, available phosphorus and pH value, respectively. In the meantime, a significant correlation was detected not only between urease activity and organic matter content, but also between protease and total nitrogen, available nitrogen, and pH values, respectively. The woodland had the lowest content of the soil total and available nitrogen, and the soil total and available phosphorus, compared to that in other land use types. The woodland might be able to effectively reduce content of nitrogen and phosphorus in the soil and hence the amont into the water body of the Three Gorges Reservoir. However, the content of soil available nitrogen, available phosphorus and total phosphorus in the hydro-fluctuation belt was the highest compared to that in other land use types The continuous agricultural farming in the hydro-fluctuation belt could be one of the crucial sources for inputting nitrogen and phosphorus into the water body of the reservoir to cause eutrophication. Thus, woodland should be further increased while imposing farming should be restricted in the hydro-fluctuation belt of the Three Gorges Reservoir area. This study provides useful knowledge for protecting results can be of help to protect riverbank slopes of the Three Gorges Reservoir.

Key words: Three Gorges Reservoir, riverbank slopes, land use patterns, soil enzyme, soil chemical properties