ABSTRACT

The impacts of climate change, in particular via elevated temperature and atmospheric CO₂ concentrations, cause differential photosynthetic responses between native and invasive alien plants, often resulting in varying magnitudes of plant growth and productivity. This study investigated variations in photosynthetic responses of an invasive alien Acacia species and two successional groups of tropical heath forest species: early secondary (Buchanania arborescens and Dillenia suffruticosa) and secondary (Calophyllum inophyllum and Ploiarium alternifolium) groups at elevated temperature (25 to 30°C) and CO₂ levels (400 to 700 ppm). Invasive A. mangium appears better adapted to higher temperature and CO₂. High temperature improved CO₂ assimilation of A. mangium compared to heath species, which was attributed to increased transpiration rate and stomatal conductance but decreased water-use efficiency. Photosynthetic responses showed no differences in early secondary species at elevated temperature and CO₂ but invasive A. mangium and P. alternifolium were stimulated by elevated CO₂. The greater maximum net photosynthesis of A. mangium coincided with lower light compensation point and electron transport rate for RuBP regeneration, to a certain extent. Findings provide insights into possible underlying ecophysiological mechanisms contributing to the invasion success of Acacias in degraded tropical heath forests in response to future climate change.

摘要

气候变化的影响，特别是通过升高的温度和大气 CO ₂浓度，导致本地植物和外来入侵植物之间的光合反应不同，通常导致植物生长和生产力的不同程度。本研究调查了一种外来入侵相思树种和两个热带荒地森林物种演替群：早期次生（Bucha nania arborescens和Dillenia suffruticosa）和次生（Calophyllum inophyllum和Ploiarium alternifolium）在高温（25 至 30 ℃）下光合反应的变化。°C) 和 CO ₂水平（400 至 700 ppm）。侵入性A. mangium似乎更好地适应了更高的温度和 CO ₂。与健康物种相比，高温改善了A. mangium 的CO ₂同化，这归因于蒸腾速率和气孔导度增加，但水分利用效率降低。在升高的温度和 CO ₂下，早期次生物种的光合反应没有差异，但入侵的A. mangium和P. alternifolium受到升高的 CO _{2 的}刺激。A. mangium较大的最大净光合作用 在一定程度上与 RuBP 再生的光补偿点和电子传输速率较低相吻合。研究结果提供了对可能的潜在生态生理机制的见解，这些机制有助于金合欢在退化的热带荒地森林中成功入侵以应对未来的气候变化。