Study on the Ecological Carrying Capacity and Driving Factors of the Source Region of the Yellow River in China in the Past 30 Years

Abstract Under the influence of natural factors and human activities, the ecological environment functions in the source region of the Yellow River in China have been degrading. According to the data on land use types and areas in seven periods (1990, 1995, 2000, 2005, 2010, 2015, and 2020) of the Yellow River source region in recent 30 years, combined with the ecological footprint method, the change of ecological carrying capacity of time and space at source scale and county scale was studied. The results show that: (1) From 1990 to 2020, the grassland and unused land area in the source region of the Yellow River changed the most. During 2005-2010, a large amount of unused land in the source region of the Yellow River was converted into grassland, with a conversion amount of 7382.33 km2. It was mainly distributed in Maduo County in the west and Maqin County in the middle of the source region. (2) In the past 30 years, the ecological carrying capacity of the source region has generally shown an upward trend, indicating a better ecological environment than before. At the county level, the ecological carrying capacity of Maqin County, Maduo County, and Xinghai County was higher, while that of Zeku County, Gande County, and Henan County was lower. The absolute ecological carrying capacity of grassland has shown an upward trend, while that of woodland has shown a downward trend in the study. (3) In the study, the spatial change of ecological carrying capacity in the source region of the Yellow River has been unevenly distributed. The low ecological carrying capacity was mainly concentrated in the west; the middle part showed medium ecological carrying capacity. The south part showed high ecological carrying capacity. The ecological carrying capacity in the spatial distribution of seven counties showed an increasing trend, with Maduo increasing the most and Henan, Jiuzhi County, and Gande County increasing the least. (4) The spatial heterogeneity of absolute ecological carrying capacity in the source region of the Yellow River was high, and the overall spatial distribution changed little. The low value was mainly distributed in the northern region, while the high value was distributed in the northwest region. (5) The land use in the source region of the Yellow River has been rational, and the ecological carrying capacity and absolute ecological carrying capacity have shown an increasing trend. The ecological environment in the Yellow River's source region has gradually improved. This research is of great significance to the sustainable supply of ecological carrying capacity, as well as the protection and restoration of the ecological environment. For further, it benefits the economy and society's sustainable development and ecological security in the middle and lower reaches of the Yellow River.(6) The ecological carrying capacity of the source region of the Yellow River shows a positive correlation with SPLIT(Separation index), PARA_MN(Perimeter-area ratio), and COHESION(Patch connectivity index), while SHDI(Aroma Diversity Index), IJI(Dispersion and juxtaposition index), PD(Patch density), LPI(Maximum patch index) show a negative correlation. The second axis of RDA mainly responds to the relationship between landscape pattern indices. It can be seen that the main landscape pattern index affecting the ecological carrying capacity of the source region is SPLIT(Separation index), followed by COHESION(Patch connectivity index), while LPI(Maximum patch index) is weaker for the ecological carrying capacity of the source area. For landscape-level landscape indices, ecological carrying capacity (EC) was significantly correlated with each landscape-level index (P<0.05), with SPLIT having the strongest explanatory power.(7) The main drivers affecting the ecological carrying capacity of the source region of the Yellow River are the social factors population, urban population, GDP, GDP per capita, animal husbandry, total energy production, the output value of the primary industry, the output value of the secondary industry, the output value of the tertiary industry, and the natural factors precipitation and evaporation.