Fine-root morphology of woody and herbaceous plants responds differently to altered precipitation: A meta-analysis

The growth of plant roots and their acquisition of resources are significantly impacted by changes in precipitation patterns. Although numerous studies have examined the impact of precipitation on fine root systems, the rooting strategies of woody and herbaceous plants under different precipitation patterns remain to be comparatively evaluated. Accordingly, in the current study, we conducted a meta-analysis of 64 peer-reviewed articles to explore the response of 17 biomass and fine-root traits of woody and herbaceous plants to precipitation changes. Our findings demonstrate that woody and herbaceous plants have developed different root strategies to cope with altered precipitation. Specifically, when precipitation increased, the fine roots of woody plants had a larger surface area and significantly increased shallow root growth. In contrast, the fine-root morphological traits of herbaceous plants showed a stronger response to increased precipitation, in which fine-root length, volume, and tissue density increased. This may result in more effective use of available water by herbaceous than woody plants. When precipitation decreased, woody plants displayed more active fine-root morphological alterations, presenting a conservative fine-root phenotype of resource acquisition, with lower specific root length and higher fine-root tissue density. Moreover, woody plants transfer absorptive fine-root structures to deep soil layers, whereas herbaceous plants are less drought-tolerant. Furthermore, woody plants may allocate biomass more optimally than herbaceous plants in precipitation-reduction scenarios. Increased precipitation may boost soil carbon sequestration and stability in woody plant-dominated forest ecosystems under future climate change scenarios, while drought may considerably reduce soil carbon storage in grassland ecosystems. In more arid environments, where woody and herbaceous plants coexist, drought may lead to the expansion of woody plants and subsequent predominance of woody plants vegetation change. our findings will fill knowledge gaps in the literature regarding the effects of precipitation changes on the fine-root dynamics of various functional plants and will improve predictions of the vegetation dynamics of forests, grasslands, and other ecosystems vegetation dynamics under changing precipitation patterns.