SOIL NUTRIENT CHARACTERISTICS OF GRAIN TO GREEN PROGRAM OF MAIN VEGETATION TYPES IN A SMALL WATERSHED, WULING MOUNTAIN AREA, CHINA.

In the present investigation, soil nutrient characteristics of three stands were studied. The soil organic matter content showed a hierarchy of Pinus massoniana forest > slope farmland > Eucommia ulmoides plantation> maple-Cinnamomum camphora mixed plantation in horizontal direction. However, with an increasing depth of soil layer, the soil organic matter content showed a decreasing pattern. The soil total nitrogen phosphorus and potassium contents of different vegetation types followed a pattern of Eucommia ulmoides plantation > maple-Cinnamomum camphora mixed plantation > Pinus massoniana forest > slope farmland. In this, the soil total nitrogen and phosphorus content decreased significantly with the increase in soil depths. The soil available nitrogen, potassium and phosphorus content of different vegetation types exhibited a pattern which follows slope farmland > Eucommia ulmoides plantation > maple-Cinnamomum camphora mixed plantation > Pinus massoniana forest. The soil available nitrogen, potassium and phosphorus content decreased with the soil depth increase. The pattern followed for soil trace elements of different vegetation types were Eucommia ulmoides plantation > slope farmland > Pinus massoniana forest > maple-Cinnamomum camphora mixed plantation. The average contents of trace elements in 0-10 and 10-20 cm of soil layer followed a gradation of Fe > Mn > Zn > Pb > Ni > Cu > Cd. 'Grain to Green Program' increased the soil nutrient content of different vegetation types, and soil nutrient content decreased with the soil depth increase. In this study, significant correlations were observed among soil nutrient elements in different vegetation types. [ABSTRACT FROM AUTHOR]