Soil moisture stability of rangeland is higher than that of woodland and cropland in the Loess Plateau, China

Abstract

Soil moisture (SM) affects ecosystem homeostasis through interactions among land use type (LUT), precipitation, heat and human activity (HA). In the core areas of China Loess Plateau, we selected three sites along gradients of annual precipitation and annual accumulated temperature ≥ 0℃ and compare SM variations among three LUTs, including cropland, woodland, and rangeland, and in three precipitation years, including dry, wet, and normal year. The SM of three LUTs were sensitive to wet years in the north, dry years in the south, and both wet and dry years in the middle, respectively. From north to south, water use (WU) increased while water use efficiency (WUE) decreased. The WU for cropland was the highest and WUE was the lowest, while rangeland had the opposite tendency. The mean annual water deficiencies for cropland, rangeland and woodland were 42.41 mm, 21.38 mm, and 15.49 mm, respectively. HA for three LUTs increased as precipitation increased and the order was cropland > woodland > rangeland. The stability of SM to precipitation was as following order: rangeland > woodland > cropland. Rangeland was insensitive to precipitation, while cropland was sensitive to precipitation. Productivity of rangeland and cropland were stabilized mainly by increasing resistance to SM and the resilience to SM, respectively. To maximize the WUE of the rain fed system and enhance the stability of SM, the area ratios of cropland, woodland, and rangeland were recommended as 4:2:19, 3:2:5 and 3:2:4 in the northern, central, and southern regions, respectively.