Change Mechanism And Prediction Of Terrestrial Ecosystems Carbon Storage In The Yellow River Basin

The Yellow River Basin is an important ecological protection area,an ecological corridor connecting the Qinghai-Tibet Plateau,the Loess Plateau and the North China Plain,and an important carbon sink area of terrestrial ecosystem.Since the 21st century,land use change in the basin has had a significant impact on ecosystem service functions,and the spatio-temporal pattern of carbon stocks has also changed.Therefore,accurate estimation of ecosystem carbon storage and its spatial distribution and influencing factors are of great significance for regional ecological management and the realization of the"two-carbon"goal.At present,domestic and foreign researchers have conducted a lot of studies on carbon storage and carbon sequestration potential at national and regional scales.However,the status quo,spatial structure and driving factors of carbon storage in the Yellow River Basin remain unclear.Based on this,this paper selected the terrestrial ecosystem of the Yellow River Basin as the object.Based on a large number of measured sample points,the paper estimated the carbon storage from 2000 to 2020 by using geographically weighted regression,including the carbon storage of abovemonthly biological carbon pool,underground biological carbon pool and 0-100cm soil carbon pool,and analyzed the impact of land use on carbon storage.The main influencing factors of each carbon pool were discussed with the help of the geographic detector,and the carbon sequestration potential under different scenarios during 2030-2050 was predicted.The main conclusions are as follows:（1）The Yellow River Basin accounts for 8.28%of China’s total area,and its total ecosystem carbon reserves are about 8.84×10⁹tons,equivalent to 8.91%of China’s terrestrial ecosystem carbon reserves.Aboveground carbon storage,underground carbon storage and soil carbon storage were 5.65×10⁸tons,4.48×10⁸tons and 7.93×109 tons,respectively.In recent years,a number of major ecological restoration measures have been implemented in the Yellow River Basin,such as returning farmland to forest（grass）,and vegetation coverage has increased significantly.Carbon sequestration has been achieved during 2010-2020,but carbon storage has not recovered to the level of 2000.During this period,the types of ecosystem in the basin changed greatly,and the changes of carbon stocks in each ecosystem were also drastic.Forest ecosystem was the main contributor to the increase of carbon stocks,and the change of carbon stocks was directly related to the change of carbon density in the ecosystem.（2）The spatial pattern of ecosystem carbon storage in the Yellow River Basin was mainly affected by altitude,temperature and precipitation.Due to the large span of this region,climate factor is the main limiting factor of vegetation growth.Meanwhile,terrain and altitude will also affect the distribution and growth of vegetation,thus affecting the distribution of carbon storage.In the past 20 years,the distribution range of the high value area of carbon storage remained stable on the whole,but the distribution of the optimal factors varied greatly among the carbon pools.The areas with high total carbon reserves in the Yellow River Basin are:average annual temperature of-5～0℃,precipitation of more than 400mm,altitude of more than 3500m,slope of more than 25°,NPP of 3000～4000 kg·m^-2,population of 0～100 people·km^-2,GDP of 0～1 million yuan·km^-2,and landform of medium-rolling mountain.（3）From the perspective of different future development scenarios,ecological protection scenario（Q3）has the best carbon gain,followed by urban restricted development scenario（Q4）,natural development scenario（Q1）,and cultivated land protection scenario（Q2）.Q3 can limit the probability of forest,grassland and river transfer to construction land to reduce land reclamation and construction land expansion,thus keeping carbon stocks stable.On the contrary,due to the rapid expansion of land reclamation,Q2 encroached on forests and grasslands with higher carbon density,resulting in a greater reduction of carbon storage than Q1.The upper reaches of the basin had the largest change in carbon storage because of its large carbon storage base.The lower reaches of the basin have the most obvious changes in carbon storage due to the rapid socioeconomic development.In the future,appropriate ecological protection policies can be developed based on the Q3 scenario to help achieve improved ecosystem stability and the“two-carbon”goal.