Short-Term Photosynthetic Responses of Selected Kerangas Species in Northwest Borneo to Changes in Leaf Temperature and CO₂ Concentration

Abstract

Climate change, which includes rising temperatures and elevated atmospheric CO₂ concentrations, has a significant effect on photosynthesis and plant adaptation. This study examines how four native species from Kerangas forests respond to changes in temperature and CO₂ levels through photosynthesis under climate change stress. The species are Buchanania arborescens, Dillenia suffruticosa, Calophyllum inophyllum, and Ploiarium alternifolium. Photosynthetic parameters, including Amax, Aqe, LCP, Vcmax, and J, were measured to assess carbon assimilation efficiency and physiological performance under controlled temperature and CO₂ conditions. The results showed substantial differences between the species. For example, among the four species, C. inophyllum and P. alternifolium demonstrated higher maximum photosynthetic capacity (Amax) and electron transport potential (J) compared to B. arborescens and D. suffruticosa, indicating greater potential for carbon assimilation under the tested chamber conditions. Higher CO₂ levels generally increased photosynthetic rates. The results highlight the importance of species-specific approaches for managing and protecting forests, particularly to enhance the resilience of tropical heath forests to climate change. Promoting native species with strong adaptive traits can support reforestation and help maintain ecosystem balance.