Research on Vegetation Restoration of Water-level-fluctuating Zone in Dry-hot Valley Reservoir: A Case Study of the Baihetan Reservoir

Plant growth in the water-level fluctuating zone of dry-hot valley reservoir is subject to periodic water flooding and high temperature, and regional vegetation recovery is quite difficult. To solve difficulty of ecological restoration in the dry-hot valley, vegetation restoration of the water-level fluctuating zone in the Baihetan Reservoir located in Jinsha River was conducted. This study selected suitable plant species for vegetation restoration through hydrological analysis and field surveys, and proposed geogrid engineering measures and elevation-based plant arrangement. The application and effectiveness of vegetation restoration were analyzed by systematically investigating survival and growth of planted plants in experimental site. The results showed that vegetation restoration in the drawdown zone of dry-hot valley reservoir was recommended to allocate native plants such as Leucaena leucocephala, Jatropha curcas, Morus alba, Canna indica, Cynodon dactylon, Xanthium sibiricum and Pennisetum sinese in the upper section, arrange flood-tolerant plants such as Salix hybrid, Pterocarya stenoptera, Betula nigra, Cornus quinquenervis, Salix variegata and Cynodon dactylon in the middle section, and prioritize flood-tolerant herbaceous plants such as Xanthium sibiricum and Cynodon dactylon in the lower section. Saplings exceeding 5 cm in diameter at breast height were suitable for vegetation restoration. Plants in experimental area adopted different growth strategies to acclimate to the arid and hot environment, exhibiting distinct morphological adaptations such as new branches sprouting from the lower trunk, dieback of the upper trunk, basal budding, or many root sprouts. Geogrid engineering measures could create near-natural habitat and conserve water and soil effectively in middle and lower section of the drawdown zone in dry-hot valley. These results provide scientific basis and practical reference for the ecological restoration in fluctuating zone of the dry-hot valley reservoir.