Unveiling plant adaptations: How limestone outperforms dolomite in water supply capacity

Typical karst landscapes in southwest China with differing lithologies: dolomite and limestone. Karst landscapes, characterized by thin soils atop soluble carbonate bedrock, exhibit rapid hydrological dynamics. Lithology is known to influence vegetation growth by affecting regolith water retention, but the impact of lithological composition on plant adaptation strategies and fluctuations in water availability remains poorly understood. We sampled 13 dominant woody plant species (8 on dolomite and 9 on limestone), including 4 overlapping species, on a monthly basis. Key functional traits, including leaf water content (LWC), leaf area (LA), specific leaf area (SLA), chlorophyll, and hydrogen (δD) and oxygen (δ 18 O) isotope ratios of xylem water, were measured to assess plant adaptation strategies to their respective lithologies. Plants on dolomite exhibited significantly lower LWC and smaller LA (P < 0.01), indicating limited access to root-zone water. Dolomite plants had lower SLA and chlorophyll (P < 0.01), and showed shifts in water source use between dry and wet seasons, whereas limestone plants exhibited fewer variations in traits beyond water source shifts. The findings suggest that species in limestone-derived forests may be more resilient to water stress and climate variability, benefiting from a more stable water supply compared to species in dolomite habitats. This research underscores the importance of considering lithological variations in predicting the vulnerability of karst ecosystems to climate change. • Bedrock lithology strongly influences plant adaptation in karst ecosystem. • Limestone bedrock provide better water supply capacity for plants than dolomite. • Species in limestone forests tended to be more resilient to hydroclimatic variability. • Lithology regulates karst forest restoration under intensifying water constraints.