Spatial analysis of the soil total carbon in Ili, Xinjiang Uygur Autonomous Region, China

Currently, the studies of soil total carbon of grassland are mainly focused on traditional statistical analysis based on survey data and spatial analysis of soil total carbon are limited. The present study attempted to apply multi-source data including field survey soil total carbon data, remote sensing data and meteorological data obtained from 146 grassland sampling plots by using geostatistics to study the spatial analysis of soil total carbon data in the Ili region, located at the northwest margin of Xinjiang Uygur Autonomous Region. The results show that there was a significant correlation between the total carbon content from various depths (0-10, 10-20, 20-30, 30-40 cm and the mean of four soil depths) and altitude, average annual temperature, annual precipitation, ≥10 ℃ annual accumulated temperature, humidity and NDVI. A comprehensive evaluation model was established using this six ecological factors, and the spatial distribution pattern of grassland soil total carbon content was inversed with 1 km spatial resolution. The soil total carbon content in 0-40 cm depth was 4.2519% and it decreased with the increase of soil depth. The results indicated that the spatial distribution of soil total carbon content in different depths significantly varied in areas of Ili. The total carbon content in high altitude region was higher than that of the river valley. The highest total carbon content was distributed on northern slopes of the Southern Tianshan mountains and southern slopes of Boluokenu mountains, and the lowest was found in intensive human activity areas, distributed in both sides of Ili river and interchange of the Teks River and the Ili River. The results indicated that the spatial distribution of soil total carbon content was correlated with the types of grassland in Ili, soil total carbon content significantly influenced by human activities, i.e. overgrazing, blind land reclamation.