Alpine grassland degradation index and its response to recent climate variability in Northern Tibet, China

Northern Tibet is the headstream region for the Yangtze, Nu (Salween River), and Lancang (Mekong River). Sustaining the environmental conditions in the region is vital for Tibet and, as the source of many rivers, the whole of China and much of Asia. The study combines remote sensing data with data from other sources and national standards of grassland degradation index to assess alpine grassland degradation index between 1981 and 2004 in Northern Tibet. A Geographical Information System (GIS) was used to examine trends in grassland degradation index and its response to climate variability, including precipitation, temperature, and solar radiation. The results show that degradation has been very serious. The areas with a significant grassland degradation index trend accounted for 23.3% of the total grasslands in Northern Tibet. During 1981–2004, precipitation variability has benefited the recovery and protection of the grasslands, while temperature and solar radiation variability exacerbated grassland degradation index in Northern Tibet. The impact of regional climate change on grassland degradation index was on the balance more detrimental than positive from 1981 to 2004.