Publications

Wan, H; Guo, P; Luo, L; Zhao, YC; Zhao, Y; Wang, XY (2022). Different remote sensing indicators reveal the transitions of two states along elevation gradients within the Xinjiang Tianshan Bogda Natural World Heritage Site. INTERNATIONAL JOURNAL OF APPLIED EARTH OBSERVATION AND GEOINFORMATION, 111, 102842.

Abstract
In mountainous regions, steppe degradation and desertification, which are transition processes between temperate deserts and montane steppes, are considerably affected by climate change and human disturbance. Consequently, the study of the transition ranges along the elevation gradient is particularly important for the protection, restoration, and sustainable development of natural heritage sites in arid areas. In this study, frequency analysis and the Akaike information criterion (AIC) were used to reveal the existence of two distinct potential states based on three remote sensing indicators (NDVI, normalized difference vegetation index; FVC, fractional vegetation cover; and LST, land surface temperature). The transition ranges of the two ecosystem states along altitudinal zonation were then quantitatively identified using potential energy analysis with a combination of multiple indicators. The results showed that the frequency distribution exhibited two conspicuous modes, the AIC exhibited a sharp decline from modes 1 to 2 and then remained stable with slight fluctuations from modes 2 to 5. Both features of the three indicators indicated the existence of two distinct potential states: temperate deserts and montane steppes. The two states and their transitions along the elevation gradient were detected using a potential analysis model for all three indicators. The results showed that the three indicators revealed the existence of two states, and the state with high NDVI/FVC values or low LST values began to show more attraction than the state with low NDVI/FVC values or high LST values at approximately an elevation of 1066 m. Temperate deserts below an elevation of 1060 m with montane steppes occurring above 1094 m, and two states coexisted between them. Furthermore, the distribution characteristics of local indicators of spatial association high-high, low-low, and not significant with elevation were analyzed, and the transition range (NDVI/FVC, 1040-1100 m; LST, 1040-1150 m) between different modes was consistent with those of the potential analysis, indicating the reliability of the results. This study successfully introduced the theory of multi-stable states and shifts between ecosystem states, and the potential energy analysis model into the study of natural altitudinal zones for mountainous natural world heritage sites, which will provide a scientific basis for the protection and restoration of steppe degradation in alpine regions.

DOI:
10.1016/j.jag.2022.102842

ISSN:
1872-826X