Abstract:Increasing anthropogenic activities have significantly altered ecosystems in arid oasis regions. Estimating the impact on a wide range of ecosystem services is important for decision making and the sustainable development of these regions. This study analyzed time-series Landsat data to determine the influences of oasis land-use changes on the ecosystem services in the Kashgar region in Northwest China. The following results were found. The total value of the ecosystem services in the Kashgar region were approximately $10, 845.3, $11,218.6, $10,291.7, and $10,127.3 million in 1986, 1996, 2005, and 2015, respectively. The water supply, waste treatment, biodiversity protection, and recreation and cultural services were the four ecosystem services with the highest service value, contributing 77.05% of the total ecosystem services. The combined contribution rate of food production and raw material value was only about 4.02%, relatively small. The sensitivity analysis indicated that the estimated total ecosystem service value (ESV) for this study area was relatively inelastic with respect to the value coefficients. The findings of this study will be crucial for maintaining the stability and sustainable development of the oasis region, where socio-economic development and the integrity of the natural ecosystem complement each other. Furthermore, the results provide a scientific basis for decision makers in land use management, and provide a reference for researchers in the Northwest China.

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This study explores a paradigm of sustainable land use in the oases along the Tarim River of northwest China, where a fragile, semi-arid riparian ecosystem is being damaged by excessive land and water use for agriculture, especially for the growing of cotton. The reliance of agriculture on water-demanding cash crops in this region poses a grave threat to survival of the natural Tugai vegetation in the area and to the long-term sustainability of the region. We explored the hypothesis that the species Apocynum pictum (A. pictum), known as Lop-Kendir by locals, and the Chinese red date (Zyzyphus jujube) may act as sustainable crop substitutes for the region, thereby replacing the widely distributed cash crop of cotton that has high water demands. Therefore, we investigated current utilization and cost-revenue structure of these two alternative plants and compared the results to cotton. Three natural resource management types of A. pictum were both identified in the wild and cultivation, with cost-revenue analysis carried out for each. The results show that all three types of institutional arrangements of natural resources, which are namely open access, ranching and farming, were present in our study and at various levels for A. pictum. A. pictum farming costs 16,250.25 yuan/ha, generates 49,014.45 yuan/ha of revenue from raw materials and brings a profit of 32,764.2 yuan/ha, which is the highest of all three cash crops compared. The Chinese government encourages Chinese red date plantations with a "Grain for green" campaign in the Tarim Basin with this plant being more profitable than cotton, which could serve to diversify the region's agriculture. We conclude that A. pictum offers opportunities for the restoration of vegetation in riparian ecosystems on salinized sites under the arid conditions of the Tarim Basin. Furthermore, it can serve as a viable land-use alternative to cotton for cash crop agriculture, as it may generate a certain income in the form of tea and fibers as well as fodder for livestock.

Carbon management in forests has become the most important agenda of the first half of the 21st century in China in the context of the mitigation of climate change impact. As the main producer of the inland river basin ecosystem in arid region of Northwest China, the desert riparian forest maintains the regional environment and also holds a great significance in regulating the regional/global carbon cycle. In this study, we estimated the total biomass, carbon storage, as well as monetary ecosystem service values of desert riparian Populus euphratica Oliv. in the lower reaches of the Tarim River based on terrestrial forest inventory data within an area of 100 ha (100 plots with sizes of 100 m × 100 m) and digitized tree data within 1000 ha (with 10 m × 10 m grid) using a statistical model of biomass estimation against tree height (TH) and diameter at breast height (DBH) data. Our results show that total estimated biomass and carbon storage of P. euphratica within the investigated area ranged from 3.00 to 4317.00 kg/ha and from 1.82 to 2158.73 kg/ha, respectively. There was a significant negative relationship (p < 0.001) between biomass productivity of these forests and distance to the river and groundwater level. Large proportions of biomass (64% of total biomass) are estimated within 200 m distance to the river where groundwater is relatively favorable for vegetation growth and biomass production. However, our data demonstrated that total biomass showed a sharp decreasing trend with increasing distance to the river; above 800 m distance, less biomass and carbon storage were estimated. The total monetary value of the ecosystem service "carbon storage" provided by P. euphratica was estimated to be $6.8 × 10 4 USD within the investigated area, while the average monetary value was approximately $70 USD per ha, suggesting that the riparian forest ecosystem in the Tarim River Basin should be considered a relevant regional carbon sink. The findings of this study help to establish a better understanding of the spatial distribution pattern of P. euphratica forest under water scarcity and can also provide an alternative approach to local decision-makers for efficient and precise assessment of forest carbon resources for emission reduction programs.