Choosing an optimal land-use pattern for restoring eco-environments in a semiarid region of the Chinese Loess Plateau

The natural environments in the semiarid regions of the Chinese Loess Plateau (CLP) are fragile due to the serious soil erosion and the weak ecological services of the plants. To ascertain and then evaluate a sustainable land-use pattern in these regions, we selected six typical land-use patterns (i.e., a farmland, a natural grassland, a homogeneous shrubland (S), a mix of shrubland and cultivated grassland (S-Alf), a mix of shrubland and orchard (S-O) and a mix of shrubland and grassland (S-G)) on the plateau and then measured the soil water, related soil properties and plant root indices to a depth of 1800 cm. We also measured the aboveground net primary productivities (ANPPs). The mean soil water content (SWC) within the 0-1800 cm profile was significantly highest (15.2%) in farmland, followed by grassland (11.4%) and S-Alf (8.0%). The available water (AW), the ratio between AW and AW capacity, and the thickness of the dried soil layers also demonstrated that farmland had the best conditions of soil water, followed by grassland and shrubland. The aboveground biomasses of grassland in both non-growing (140 g m−2) and growing (370 g m−2) seasons were significantly higher than those of shrublands. The ANPPs of the grassland (2.0 g m−2 d−1) demonstrated a similar trend. The patterns of land use (including the mixtures of different plant species) greatly affected the patterns of vertical distribution and quantities of soil water within the 1800-cm profile. The data for the soil-water regime and the ANPP further indicated that grassland would be an optimal use of the land for these semiarid regions. This information should be useful to the ecological scientists and policy makers for developing strategies for the sustainable management of vegetation on the CLP and possibly other water-limited regions around the world.