We measured water use efficiency (WUE) of dominant species across three distinct restoration stages (shrub, secondary forest, and primary forest) in karst peak-cluster depression region using stable carbon isotope technology. The results showed that foliar δ13C values of 12 dominant tree species ranged from -32.1‰ to -29.0‰. The WUE for these dominant species ranged from 18.25 μmoL·moL-1 to 36.23 μmoL·moL-1, with the lowest WUE in Pittosporum tobira and the highest WUE in Pterolobium punctatum. The hierarchy of WUE across different restoration stages was in order of shrub > secondary forest > primary forest. The WUE for a particular species was higher during early-stage vegetation recovery compared to late-stage. Furthermore, when considering different life forms, WUE was in order of liana > shrub > tree. From the shrub stage to the primary forest stage, deciduous species exhibited higher WUE than evergreen species. In summary, plant WUE gradually declined with the ongoing vegetation restoration process in this region. Enhancing WUE was one of the principal strategies for plant adaptation to drought-prone habitats within karst peak cluster depression region. Therefore, priority should be given to lianas and shrubs characterized by high WUE when selecting appropriate species for reforestation efforts in karst regions subject to seasonal or geological droughts.
本研究利用稳定碳同位素技术研究喀斯特峰丛洼地3 个不同恢复阶段(灌丛、次生林、原生林)优势植物的水分利用效率,分析植被恢复过程中其水分利用策略。结果表明: 12 种优势植物叶片δ13C值的范围为-32.1‰～-29.0‰。各优势植物的水分利用效率变化范围为18.25～36.23 μmol·mol-1,其中,海桐的水分利用效率最低,老虎刺的水分利用效率最高。不同恢复阶段的水分利用效率大小顺序为灌丛>次生林>原生林,且同一物种在植被恢复前期的水分利用效率高于植被恢复后期。不同生活型植物的水分利用效率大小顺序为藤本>灌木>乔木。从灌丛阶段至原生乔木林阶段,落叶植物的水分利用效率均高于常绿植物。随着植被恢复,植物的水分利用效率逐渐降低,提高水分利用效率是喀斯特峰丛洼地植物适应干旱生境的主要策略之一。在时常遭遇季节性或地质性干旱的喀斯特地区进行植被恢复时,应优先选择水分利用效率较高的藤本和灌木。.
Keywords: karst; peak-cluster depression; vegetation restoration process; stable carbon isotope; water use efficiency.