21. Study area
The study area (214,100 km2) is the Great Taihang Region (34° 34′ ~ 40° 47′ N, 110° 14′ ~ 116° 34′ E),located in the north of China and covers the entire territory of Shanxi province, as well as some districts and counties in Beijing, Hebei and Henan provinces, accounting for about 2.2% of China’s terrestrial area (Fig. 1). In the study area, cropland covers 37% of this area, forest 35%, and Grassland 21%. There are various geomorphic types, including mountains, hills, platforms and plains. The eastern part is a massive mountain formed by the Taihang Mountain, and the western part is the Loess Plateau with Lvliang Mountain as the trunk (Fig. 2). The altitude ranges between 24 m to 3091 m. The climate in this region is temperate continental monsoon climate and the four seasons is distinct, with mean annual temperature between 8 and 13°C, and average annual precipitation between 400 and 1000 mm. Rainfall is concentrated from July to September. Deciduous broad-leaved forest is the most widely distributed plant community in the study area. Deciduous broad-leaved forest and secondary deciduous shrub are mainly distributed in the South, while temperate shrub and semi-arid grassland located in the northern part. The study area is mainly mountainous area, and the diversity of geographical environment leads to a good variety of flora and fauna.