Abstract:
Ten remote sensing inversion indexes related to the ecological environment were selected, combined with principal component analysis (PCA), the ecological environment index (RSEI) and water conservation function index (WCI) were constructed and classified, the ecological environment, water conservation capacity and temporal and spatial pattern changes of the red line area for ecological protectionof Yalong River source from 2000 to 2019 were evaluated. The results show that: (1) The RSEI of eastern part was slightly better than that of the western part, the area with excellent evaluation grade accounted for 15.96%, the good accounted for 51.28%, the general accounted for 27.61% and the poor accounted for 5.13%. The propotion of regions with slight improvement in RSEI trend was 52.96%. The northeast showed a slight improvement and the east showed a slight degradation. The degraded areas were scattered. (2) The ecological function of water conservation remained good, the WCI of the north was better than that of the south. The areas with worse, poor and general evaluation grades were mainly distributed in the central and south region, and were scattered. The proportion of areas with excellent WCI rating accounted for 43.22%, the good accounted for 35.71%, the general accounted for 17.45%, the poor accounted for 3.48% and the worse accounted for 0.02%. The change trend of WCI was mainly slightly improvement in the northwest and had greatly spatially difference, while it significantly improved in the south. (3) Since 1990, the temperature rising rate in the study area was 0.56 ℃/10a, the average temperature rising rate in the growing season was 0.1 ℃/10a, the precipitation rising rate was 27.7 mm /10a, and the average precipitation rising rate in growing season was 83.5 mm/10a. (4) Overall, from 2000 to 2019, the climate warming and humidifying in the study area was beneficial to vegetation restoration, carbon storage and reduction of soil erosion, and the ecological environment and water conservation function were improved.