Functional diversity buffers biomass production across variable rainfall conditions through different processes above‐ versus below‐ground

Understanding precipitation controls on functional diversity is important in predicting how change rainfall patterns will alter plant productivity the future. Trait-based approaches can provide predictive knowledge about certain species behave and interact with community. However, relates to above- below-ground biomass production variable conditions remains unclear. Here, we tested role of mass ratio niche complementarity hypotheses shaping biomass–functional relationships seasonal drought. We implemented a fully crossed experiment that manipulated drought timing (fall dry, spring consistent dry ambient rainfall) community composition (grass-dominated, forb-dominated mixed grass–forb) California annual grassland. Plant communities groups showed higher than either grass- or forb-dominant communities. found divergent diversity–biomass for biomass. Above-ground decreased weighted means (CWMs) specific leaf area (SLA) height, supporting hypothesis, which posits dominant traits drive Below-ground no evidence hypothesis complementarity. While was largely unaffected by one season, community-wide trait shifts response treatments. shifted SLA compared ambient. longer, finer denser roots fall shorter coarser dry. Functional buffered enabling across conditions. Read free Plain Language Summary this article Journal blog.