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Changes in carbon sources and sinks in terrestrial ecosystems are closely related to the evolution of land use / cover change （LUCC）. The mechanisms of land use change on carbon stocks in terrestrial ecosystems were investigated to provide theoretical references to understand the influence of spatio-temporal evolution patterns on regional carbon stocks. Based on the LUCC data of 1980—2020, the spatio-temporal dynamics of LUCC of the Yili Valley in 2030 were simulated through multi-criteria evaluation（MCE）, cellular automata （CA）, and Markov chain models. InVEST model explored the spatio-temporal evolution pattern of carbon stocks in the Yili Valley terrestrial ecosystem from 1980 to 2030 under the land use change. The results showed that the MCE-CA-Markov model predicted LUCC data set and the actual LUCC in 2000, 2010, and 2020, and their Kappa coefficients were 0.929 1, 0.875 5, and 0.929 7, respectively, indicating that model simulation was highly generalized and could be used to accurately assess the spatio-temporal evolution of carbon stocks in subsequent years; the InVEST model estimated that the total carbon stock of the Yili Valley was 1 114.95 Tg in 1980, and it would show a decreasing trend until 2030, with a cumulative net decrease of 65.9 Tg. The retreat of forest and grassland area was the dominant factor leading to the decrease in carbon stock; and the spatial distribution of carbon stocks in the Yili Valley was generally characterized by a nested distribution of high value areas around low value areas. The high value areas of carbon density were distributed in the southern and northern mountainous forests and grasslands, while the low value areas were concentrated in the central valley plains. Studying the impacts of land use change on the carbon stock of terrestrial ecosystems can provide data support for carbon pool management in the study area, and subsequently, provide theoretical reference for the formulation of carbon sequestration and environmental protection policies. [ABSTRACT FROM AUTHOR]

[Objective] Studying the characteristics of soil nutrient changes is of great significance for soil nutrient management, scientific fertilization, and sustainable agricultural development. [Method] This study takes Fukang city as an example. Based on the soil nutrient survey data of three periods (1982, 2010, 2018), using classical statistics, geostatistics, geoscience information maps, etc., the organic matter, alkali nitrogen and effective nitrogen were compared and analyzed. The spatial variability and grade change characteristics of phosphorus and available potassium in different periods. [Result] (i) In the past 40 years, the soil nutrient content in the study area showed that the organic matter content decreased first and then increased, the alkali nitrogen increased first and then decreased, and the available phosphorus and available potassium content increased. (ii) Spatial structure characteristics in addition to the strong correlation of organic matter in 2010, the other nutrients showed moderate intensity correlation in each period, with random variation as the main factor and structural variation second. (iii) In terms of grade changes, the lower levels of alkaline nitrogen nutrient levels were mainly concentrated in grades 4 and 5, and the other nutrients were at medium or medium upper levels. [Conclusion] There were differences in nutrient contents in different periods. In addition to the obvious lack of alkali nitrogen in soil nutrients in various periods in Fukang city, organic matter, available phosphorus and available potassium reached medium or above levels. This study provides a scientific basis for the basic farmland construction and nutrient management in Fukang city. [ABSTRACT FROM AUTHOR]