| 摘 要： |
Rangelands are the dominant ecosystems in the Tibetan Plateau and the most critical livestock production resources. However, a large quantity of rangelands has degraded in North Tibet, with declined forage yield and invaded unpalatable weeds. Thus, identifying potential degradation is essential to manage rangelands sustainably in the future. In this study, we aimed to use an environmentally sensitive area index (ESAI) that integrated the conditions of vegetation, soil, climate, and management to assess rangeland degradation in North Tibet and identify the major drivers of degradation by the random forest model. The ESAI contained 16 indicators of the selected four categories, which were input by layers from geographic information system data. The results revealed that 33% of the study area was susceptive to rangeland degradation, in which alpine desert-steppes in the west, with the highest mean ESAI scores of 1.38, were the most sensitive areas. According to the degrees of degradation, only 9% of rangelands in the east had low mean values of ESAI (< 1.22), which were mostly located in the alpine meadow. The importance ranking for rangeland degradation based on the random forest model indicated that the highest importance was vegetation cover type, followed by grazing intensity and aridity with more than 60% mean decrease accuracy. Besides, field measurements showed that the adjusted correlation coefficient of multiple regression of four vegetation degradation indicators was 0.86, illustrating that the assessment as a proxy for rangeland degradation sensitivity is feasible. This study provides an important approach to evaluating potential rangeland degradation. Therefore, the assessment model is recommended for regional-level decision makers to manage rangeland degradation with full consideration of local physical conditions. (C) 2022 The Society for Range Management. Published by Elsevier Inc. All rights reserved. |
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