Responses of plant biomass to global warming: From leaf traits to biodiversity

Background/Question/Methods: Predicting biomass responses to global warming is of fundamental importance to clarify the debate on the positive feedback between climate warming and terrestrial carbon cycle. Unfortunately, current state-of-the-art models suffer great uncertainty in simulating and predicting the biomass responses to global warming. To identify the proper mechanisms underlying responses of carbon processes to temperature and reduce the uncertainty in model outputs, it is necessary to incorporate the information provided by the global change experiments at different scales from leaf to individual to ecosystem levels. However, as the spatial scales are usually mismatched between ecosystem models and global warming experiments, an investigation on the scaling rules of ecophysiological responses to global warming among different levels may be helpful to evaluate and improve model performance. Therefore, in this study, using a series of statistic techniques, we investigate the potential scaling relationships of warming effects among different levels from leaf to ecosystem based on 481 published papers.

Results/Conclusions: Our results showed that the biomass responses to warming at the species level were well predicted by responses of leaf area. Meanwhile, two factors that had been previously overlooked (i.e., phylogenetic information and intraspecific variation) are proved to be the most important regulators for the variation of biomass responses to global warming at the species level. When the species-level responses were scaled up to ecosystem-level, the species dominance was more important. At the ecosystem level, biodiversity played a critical role compared to thermal niche and warming magnitude. In communities with low biodiversity, biomass responses to warming are mainly regulated by diversity responses and community synchrony, while for communities with high biodiversity, biomass responses are much more stable and no significant driver is found. These results highlighted the importance of leaf area, phylogenetic information, intraspecific variation and biodiversity to the plant biomass responses to warming across scales, and suggested that these aspects should be incorporated into land surface models in order to predict ecosystem functioning under global warming more accurately and precisely.