Livestock grazing significantly accelerates soil erosion more than climate change in Qinghai-Tibet Plateau: Evidenced from 137Cs and 210Pbex measurements

Abstract

Livestock grazing and climate change accelerate soil erosion in the grassland of Qinghai-Tibet Plateau (QTP), China. However, the linkage of the two factors to accelerated erosion in the region has never been separated. Thus, this study was set up to determine the contribution of livestock grazing and climate change to soil erosion in the grassland of QTP. Five sites (Tuotuohe, Maduo, Maqin Dongqinggou (MQDQG), Maqin Junmuchang (MQJMC), and Maqin Jungongzhen (MQJGZ)) across 1100-km East-West transect in the Three-River Headwaters Region (TRHR) of QTP were selected for this study. The 137Cs and 210Pbex techniques were used to determine soil redistribution rates, covering a time scale of 50 and 100 years, respectively. In the last 100 years, soil accumulation was obvious in four sites (Tuotuohe, Maduo, MQDQG and MQJMC) except one site (MQJGZ), where soil erosion occurred along the transect. In the entire transect, almost no soil erosion but soil accumulation (0.25 t ha−1 yr−1) occurred over a period of 100 years. In contrast, soil erosion significantly increased by 75 times at a rate of 18.68 t ha−1 yr−1 in the last 50 years. Net soil redistribution varied significantly from −99 t ha−1 yr−1 in MQJGZ to 14.2 t ha−1 yr−1 in MQDQG over a period of last 50 years. Accelerated soil erosion across QTP significantly correlated with livestock numbers and intensive grazing activities but not significantly correlated with precipitation. Our results suggest that livestock grazing play a key role in accelerating soil erosion more than climate change in the grassland of Qinghai-Tibet Plateau.