2. Study area
The study area is located at 3500
3300–3800
4400N, 119320
500–
122430
900E, within Shandong Province, eastern China (Fig. 1). The
peninsula is composed of 14 counties and 3 cities, with a total land
area of 29,411.7 km2
. Elevations range from 0 to 1130 m above sea
level, and most agricultural lands are found in lowland areas with
elevations of less than 500 m. Climate in the Shandong Peninsula
belongs to the Asian monsoon system. Summer is warm and wet,
whereas winter is cold and dry. Monthly mean maximum air
temperature in summer is 25 C, while the monthly mean
minimum air temperature in winter is 0 C. Annual precipitation
ranges from 600 to 700 mm according to weather observation data
in the past five decades. The cropping systems in our study area
consist of double-cropping and single-cropping systems. The
double-cropping system consists of winter wheat and summer
corn, whereas the single-cropping system mainly involves peanuts.
Other major land-use/land-cover categories in the study area
include woodland (mainly deciduous trees), water, and barren
land.