Abstract:

The dry-hot valleys are primarily distributed across the Hengduan Mountains in southwest China, where a distinctive combination of water and heat conditions are formed under the influence of unique topography and local microclimate, making it the northernmost “hot spot” in China. Under the dual pressures of long-term intense human disturbance and harsh natural environments, the ecosystems in the dry-hot valleys has become extremely degraded, with structure and function on the verge of collapse, which severely restricts local economic and social development and makes them one of the most typical eco-fragile zones, extremely degraded areas, and the most difficult regions for vegetation restoration in China. This paper first briefly reviewed the history of vegetation restoration in the dry-hot valley region, then systematically analyzed the opportunities and challenges of ecological restoration in the valley area, and clearly proposed that shrub coverage technology may be the most suitable ecological restoration method for this region. This technology could overcome drought and high temperatures, two key limiting factors of vegetation restoration in valley areas, and achieve the technology goals of water conservation, soil fixation, and fertility improvement. In this paper, three principles for vegetation restoration in dry-hot valley areas were put forward for the first time: trees if suitable for trees, shrubs if suitable for shrubs, grasses if suitable for grasses, barren if suitable for barren; implement zonal vegetation restoration combining ecological conservation and industrial development; prefer native species for vegetation restoration. To assess the effects of vegetation restoration, four criteria were proposed: water and soil conservation capacity, soil ecosystem health, plant community health, and comprehensive benefits. Finally, the research on vegetation restoration in the valleys were expected to be carried out in the following four aspects: to strengthen the study on the evolution law of the community and its adaptive mechanism in the dry and hot river valley area, to establish and improve the long-term dynamic monitoring system, to select and cultivate native species, to carry out research of new vegetation restoration technologies, and implementation of demonstrations and extension.

Key words: dry-hot river valleys, water and soil conservation, ecological restoration, native species, vegetation evolution, soil health, grass and shrub coverage technology, hydrothermal conditions, dynamic monitoring