Abstract:

The dynamic change of soil organic carbon storage has a significant influence on the regional and even global carbon balance. In the rapidly urbanized area, the rapid social and economic development has made the land use/cover change intensely, and the change of soil organic carbon storage in plough layer of this area has attracted much attention. The core area of the Pearl River Delta is selected as the research area. Based on the data of soil organic carbon content of plough layer in 1980 and 2015, this paper calculates the reserves of the soil organic carbon pool of the plough layer in different time, analyzes the spatio-temporal variation characteristics of the soil organic carbon storage by the towns, and uses the geographic detector to measure the contribution of different influence factors, identifies the dominant factors affecting the spatio-temporal variation of soil organic carbon storage at the township scale. The results show that: 1) during the period from 1980 to 2015, the reserves loss of soil organic carbon pool in the core area of the Pearl River Delta was 5.91Tg, and the loss rate was 67.16%. The spatial change had the direction of the typical urban cluster, that is, the closer to the urban cluster the area is, the greater the degree of loss will be. Around the “Guangzhou-Foshan-Dongguan” town cluster, the irregular circle of soil organic carbon storage decreased significantly. 2) The spatio-temporal heterogeneity of soil organic carbon storage in the core area of the Pearl River Delta is influenced by various factors such as climate change, topography, hydrological environment, social and economic development, land use change and farmland landscape change, and the influence has great difference, and the contribution of each factor (q Statistics) ranged from 0.004 to 0.256. 3) The change of farmland landscape, pressure stress from the growth of the secondary and tertiary industries, water network density and land structure change are the dominant factors affecting the spatial and temporal changes of soil plough organic carbon storage in the core area of the Pearl River Delta. Under the interference of high intensity artificial activities such as irrigation, fertilization and artificial soil improvement, climate change and topographic conditions have no significant influence on the spatial and temporal changes of soil plough organic carbon storage at the township scale in the core area of the Pearl River Delta. The water network density determines the water environment of the farmland, which affects the soil organic carbon density of plough layer and land use/cover change, and has the most significant influence among the factors that belong to the natural geographical environment. At the same time, as the rapidly urbanized area, there was a huge benefit gap between agricultural production and non-agricultural economy in the core area of the Pearl River Delta from 1980 to 2015, which led to the sharp change in the land use/cover change and the serious fragmentation of the farmland landscape, which caused the severe changes of the soil organic carbon pool of plough layer at the township scale.

Key words: soil organic carbon, plough layer, carbon storage, geodetector, dominant factors, the core area of Pearl River Delta