Responses of plant biomass and biomass allocation to experimental drought: A global phylogenetic meta-analysis

Divergent responses of plant biomass to drought were found across hundreds of manipulative experiments. While many researchers have explored the influences of plant functional types (PFTs) and climatic conditions, few focus on the importance of evolutionary history. Here we compiled a global dataset of the responses of plant biomass and biomass allocation to the experimental drought from 281 studies conducted on 329 wild species and conducted both traditional and phylogenetic meta-analyses to explore the potential role of evolutionary history in affecting the differences among PFTs and the regulation effects of environmental conditions. We found that there were no consistent differences in biomass responses to drought between gymnosperm and angiosperm woody plants when the traditional meta-analysis was applied. Taking the phylogenetic information (the proxy of evolutionary history) into account resulted in more sensitive responses in gymnosperms than angiosperms but with great uncertainty, probably due to the high hydraulic diversity in both groups. The observed higher drought sensitivity in evergreen gymnosperms than deciduous ones, and in C3 herbs than in C4 ones were mainly derived from the phylogenetic relatedness among species. The influences of drought intensity were prevalent in both traditional and phylogenetic meta-analyses. These results highlight the vital role of plant evolutionary history played in affecting plant responses to drought. Given the potentially complicated interactions of climatic change and evolutionary history, we call for experiments that aim to investigate the role of phylogenetic relatedness on plant and ecosystem functions in future studies.