Impacts of Ground Substrate Structure on Plant Community Structure in Three Geological Formation Zones of the Jinsha River Dry-Hot Valley

Objective To investigate the effects of surface substrate structural variations in three bedrock formation areas (clastic, carbonate, and granite) on plant community patterns in the dry-hot valley of Jinsha River, providing theoretical support for ecological restoration methods and goals in fragile ecosystems.
Methods Focusing on surface substrates in clastic rock, carbonate rock, and granite formation areas of the Yuanmou Basin, Yunnan Province, field profile measurements, vegetation quadrat surveys, and soil physicochemical analyses were conducted. Vertical structures of surface substrates and vegetation in different bedrock areas were established. The impacts of spatial substrate structures and material composition differences on plant root growth space, water availability, and nutrient supply were analyzed. Geospatial sampling methods were further applied to clarify bedrock-vegetation relationships.
Results Significant differences in surface substrate characteristics were observed among the three formation areas: Clastic rock area: Dominated by topsoil-colluvial layer structures (mean thickness: 82.4 cm) and topsoil-residual layer structures (mean thickness: 74.7 cm), with 22.5% average clay content. Deep-rooted Quercus spp. trees dominated (65.7%), and species richness reached 25.4 species/100 m². Granite area: Primarily featured topsoil-residual layer structures (mean thickness: 41.5 cm), 18.5% clay content, and shallow-rooted Dodonaea viscosa shrubs as the dominant species (68%), with low species richness (7.3 species/100 m²). Carbonate rock area: Characterized by topsoil-bedrock layer structures (mean thickness: 13.4 cm), 19.3% clay content, and a mixed shrub community dominated by deep-rooted Phyllanthus emblica (35%) and shallow-rooted Dodonaea viscosa (37%).
Conclusion The study demonstrates that bedrock formation-controlled surface substrate thickness, fissure development, and water-holding capacity are key drivers of plant community diversity in dry-hot valleys. Existing bedrock formation maps can expedite vegetation restoration strategies: Clastic rock areas are suitable for artificial promotion of tree-dominated reforestation. Granite and carbonate rock areas align with natural restoration-oriented conservation models for sparse shrub-grass communities.This research provides a geological-ecological coupling theoretical framework for differentiated ecological restoration in dry-hot valleys.