Since other factors (soil properties, topography, etc.) under natural conditions are relatively invariant over one or two decades, climate variables (precipitation and temperature) and human activities are the two fundamental factors driving vegetation changes in global or large-scale areas. However, the combined effects of either single climatic factor and human activities on vegetation changes and the role of human activities itself in a specific region has not been fully discussed. In this study, the Hexi region, a typical dryland consisting of three inland river basins in northwest China was selected as a case area. A new classification framework combining Pearson correlation analysis and residual trend approach was proposed to assess their individual and conjoint contributions of climate variables and human activities in areas of significant vegetation changes. Our results indicated that most of vegetation covered areas in the Hexi region experienced significant changes during the period 2001−2017, and vegetation improvements were widespread except the interior of oases; significant changes in vegetation caused by human activities, precipitation, the interactions of precipitation and human activities, temperature, the interactions of temperature and human activities, the interactions of temperature and precipitation, and the interactions of the three factors accounted for 50.46%, 16.39%, 19.90%, 4.33%, 2.32%, 2.11%, and 4.49% of the total change areas, respectively. Generally, the influence of temperature was relatively weaker than that of precipitation, and the contributions of the interactions of climate variables and human activities on vegetation changes were greater than that of climate contributions alone. Moreover, the results of various investigations, according to the trends and the time of vegetation changes, indicate that decreasing trends of the normalized difference vegetation index (NDVI) in the Hexi region were chiefly attributed to the adjustments of agricultural planting structure while the comprehensive treatment programs implemented in river basins supported a large proportion of vegetation improvements.
The Hexi Corridor is a typical ecologically fragile and sensitive area, and the oases areas in the middle are the core area of the economic development of the Hexi Corridor, where the ecological problems are most serious. It is of great significance for regional ecological environment construction and sustainable development to clarify the ecological environment status and its change distribution of the Hexi oases areas. This study used remote sensing ecological distance index (RSEDI) model to generate time series of various environmental indexes of the Hexi oases areas from 1986 to 2020, based on Landsat TM/OLI images. And the changes of ecological environment were quantitatively analyzed by employing the coefficient of variation, Theil-Sen median trend analysis and the Mann-Kendall test, and Hurst index method. Results showed that: (1) The mean value of RSEDI of Hexi oases showed an increasing trend, increasing from 0.386 in 1986 to 0.405 in 2020. (2) The ecological environment changes of the Hexi oases were relatively stable, areas with low coefficients of variation accounted for 62.70%. (3) The ecological improvement areas (26.53%) were smaller than the ecological decline areas (30.83%), and areas with no change accounted for 42.62%. (4) 75.14% of areas were persistent, showing the ecological environment changes had strong sustainability. The areas with persistence and improvement accounted for 20.72%, which were distributed throughout the study area, mostly around the periphery of artificial oasis such as Shandan, and Yongchang. The areas with persistence and degradation accounted for 21.55%, which were concentrated in the middle of the study area, mainly
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.