On the relationship between root economics and plant hydraulic traits
Anvar Sanaei1, Srijna Saxena1,2, Kevin E Mueller3
1Institute of Biology, Leipzig University, Leipzig, 04103, Germany.
Abstract:
Drought stress constrains the productivity of terrestrial ecosystems and the distribution of plant species. To withstand drought stress, plants have evolved diverse water-use strategies. Despite the critical function of roots in whole-plant water regulation, drought strategies have been primarily studied from an aboveground perspective, and so our knowledge of how fine-root traits are related to aboveground hydraulic traits remains limited. Here, we compiled a dataset of primarily woody species comprising five aboveground plant hydraulic traits associated with water-use strategies and four fine-root traits from the root economics space (RES). We investigated how the global diversity in ecological strategies of the RES traits relates to aboveground hydraulic traits contributing to drought resistance. We found a slight trend towards acquisitive species with higher root nitrogen content and lower root tissue density having lower drought resistance in aboveground tissues. Species with thicker roots displayed a tendency towards slightly higher drought resistance than thin-rooted species. The weakness of these relationships suggests that aboveground drought adaptations are largely independent of classical axes of fine root ecological strategies, pointing to either a decoupling between aboveground and belowground responses or a stronger coordinating role for other root traits such as maximum rooting depth or root cortex fraction in hydraulic adaptation.
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