Estimation of Grassland Ecological Footprint and Ecological Carrying Capacity Based on NPP in Haiyan County, Qinghai Province

Based on NPP data and statistical data, this paper estimated the ecological footprint and ecological carrying capacity of grassland in Haiyan County from 2000 to 2020 through ecological footprint and ecological carrying capacity calculation model.The results show that the average annual NPP of grassland in Haiyan County is 368.96 g·m^-2·a^-1. NPP decreases with the increase of altitude, exhibiting a certain level of vertical zonality. In recent 21 years, the per capita ecological footprint of grassland in Haiyan County has increased slowly, and the average ecological footprint is 0.24 hm²·cap^-1. Compared with the figure in 2000, the ecological footprint of grassland in Haiyan County increased by 0.16 hm²·cap^-1 in 2020. The smallest grassland ecological footprint is distributed in the central region with strong grassland productivity, while the largest grassland ecological footprint is mainly distributed to the north of Qinghai Lake and some areas of high altitude in the north. The ecological carrying capacity shows a slightly decreasing trend, falling in the northern and central regions but rising in the southwest and southeast regions.Higher grassland ecological carrying capacity is identified in Ganzihe town, Jintan town and Qinghai Lake town, accounting for 67.93% of the total area. The average value of grassland ecological deficit/surplus is 2.87 hm²·cap^-1, increasing gradually from the periphery to the middle of the county. In general, the annual values are all greater than 0, indicating that the regional grassland ecosystem is in surplus and there is no major environmental crisis.