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Spatiotemporal characteristics of landscape ecological risks on the Tibetan Plateau

: Using the land cover data of the Tibetan Plateau in 1992, 2001, 2008, and 2015 and ArcGIS 10.5 and Fragstats 4.2 software, this research built an ecological risk index based on landscape pattern and landscape vulnerability, and used geo- statistical analysis and spatial autocorrelation analysis methods to conduct an ecological risk assessment for the Tibetan Plateau, then analyzed the spatiotemporal characteristics of landscape ecological risks. It provides a scientific basis for the prevention of land use ecological risks of the Tibetan Plateau. The results show that: (1) The distribution of landscape ecological risks on the Tibetan Plateau has an spatial aggregation effect. On the whole, the risk in the northwest is high, while it is low in the southeast. The spatial distribution of landscape ecological risks is closely related to the natural terrain of the Tibetan Plateau, which is mainly affected by the geographical conditions. (2) From 1992 to 2015, the landscape ecological risks of the Tibetan Plateau showed a downward trend, which is mainly manifested in the reduction of the high and the medium-high risk areas, and the expansion of the low and the medium-low risk areas. The main reason for this change is the influence of the warming and wetting process of the Tibetan Plateau and ecological construction on the land cover structure since the 1990s. (3) There are significant differences in the distribution and characteristics of landscape ecological risk change on the Tibetan Plateau. The regions with higher landscape ecological risk values mainly exist in the marginal areas where different terrains meet. Forest land has the highest proportion of low ecological risk areas, while barren land, glacier, and snow cover have the highest proportion of high ecological risk areas. The declining rate of barren land with high ecological risk grade was the highest, followed by grassland, which reflect that the change of barren land and grassland had the most significant impact on the landscape ecological risks of the Tibetan Plateau.