请按照nature发文标准改下下面一段话保证语言逻辑和前后关系：The alpine grassland in northwest Sichuan is one of the five major grazing areas in China which is affected by the geographical environment climate change and human fac

The alpine grassland in northwest Sichuan is one of China's five primary grazing regions. Its soil degradation is caused by a combination of factors, including geographical environment, climate change, and human activities. This degradation is characterized by soil grains that are loose and unstructured, poor fertility, and poor water and fertilizer retention performance. Studies conducted by Zhou et al. (2008) and Ma et al. (2020) have confirmed the severity of this issue.