Predictability of carbon assimilation in high biodiversity ecosystems within the context of climate change

There is an increasing need to assess carbon exchange capacity of natural ecosystems in the context of a changing climate, which is crucial for understanding their future carbon capture potential and conservation. Studies focusing on natural high-biodiversity ecosystems remain limited. Among these, islands ecosystem stands out as unique natural places where a significant altitudinal gradient, coupled with a rich biodiversity, provides an exceptional natural laboratory to evaluate how environmental changes affect the carbon assimilation of these endemic species across a broad range of ecosystems. In this study, an empirical model was developed for predicting photosynthesis and respiration responses to radiation, temperature, humidity and soil water deficits of 48 native species along an altitudinal range from arid coastal communities to high mountains through cloud forests or pine forests (Tenerife, Canary Islands). With a generally demonstrated applicability, the analysis of model parameters elucidated the influence of individual environmental factors on photosynthesis and a ranking of species sensitivity to each factor was established. Both air and especially soil moisture were found to significantly influence photosynthesis capacity. Temperature primarily affected dark respiration, indicating potential CO 2 loss escalation with rising temperatures, although its impact on photosynthesis was less pronounced compared to moisture. Notably, most parameters remained consistent across plant communities, except those associated with dark respiration and soil moisture sensitivity to precipitation accumulation. Plant water status emerges as the most influential driver of carbon uptake in the functionally diverse vegetation studied, highlighting the importance of incorporating this proxy into carbon assimilation models for future climate scenarios.