Ecological engineering projects significantly enhanced vegetation recovery: A case study from the Jinsha River Basin (Yunnan section), China

The Jinsha River Basin (JRB) has a good vegetation coverage and plays an important role in maintaining the ecological environment in the upper reaches of the Yangtze River. In this study, the effectiveness of ecological engineering implementation in the Yunnan section of the JRB was analysed from the three aspects of fractional vegetation cover (FVC), vegetation restoration potential achievement degree (VRPAD) and ecological land, and residual analysis was used to analyse the effects of ecological engineering and climate on vegetation. The results revealed that: (1) From 1990 to 2023, the interannual FVC and VRPAD were 0.65 and 0.5, respectively, and the growth rates of VFPAD and FVC were 0.32 % and 0.39 %, respectively. (2) The average annual area of ecological land was 82.05 × 10 ³ km², with a mean annual growth rate of 0.04 %, and an overall increase of 1.18 × 10 ³ km². The forestland and wetland areas both tended to increase, whereas the grassland area continued to decrease. (3) Spatially, the area of increased FVC was 70.52 % and the area of decreased FVC was 25.22 %. Compared with the period from 1990 to 2000, the VRPAD from 2000 to 2023 showed a transition from non-significant increase to a significant increase. (4) From 1990 to 2000, the area of vegetation positively affected by ecological engineering accounted for 57.39 %, and the area of vegetation negatively affected by anthropogenic activities accounted for 40.24 %. From 2000 to 2023, the area of vegetation positively affected by ecological engineering accounted for 68.28 %, and the area of vegetation negatively affected by anthropogenic activities accounted for 31.02 %. (4) In areas where vegetation improved, ecological restoration policies promoted the recovery of vegetation, which accounted for the largest area (51.88 %). In areas where vegetation has degraded, anthropogenic activities have led to vegetation degradation, accounting for the largest area (54.21 %). In the future, the influence of natural factors and human activities should be incorporated into the formulation of ecological policies.