2.1. Study area
The study area (115010–115510E, 26030–26410N) is Xingguo
county in Jiangxi province of China (Fig. 2), which is located in the
mid-southern areas and lies to the North of Ganzhou City, at the
headwaters of Pinggu River. It is surrounded by the mountains in
the east, north, and west. There is a valley basin centered in the
county in the south-central, mostly lowmountains and hills. In
2005, the GDP of Xingguo totaled 3.32 billion Yuan. The proportion
of three industrial structures is 39.3:31.3: 29.4, and the rural per
capita net income is 2376 Yuan in 2005. The study area covers
an area of 15.5km2, and the resident population was 121,000.