Abstract
How historical and concurrent drought regulate plant
diversity-productivity relationships through altering soil microbial
communities remains a key knowledge gap. We addressed this gap with
plant diversity-productivity relationship experiments under drought and
ambient conditions over two phases (Phase I: soil conditioning, and
Phase II: plant response). Our results reveal that plant diversity and
drought interacted and caused divergent soil microbial communities in
Phase I, leading to soil microbial legacies. These soil legacies
interacted and caused more pronounced plant diversity-productivity
relationships in Phase II, reflecting increased net biodiversity effects
over time. Complementarity effects were most positive in plant
communities with highest plant richness and in the Drought-Ambient
(Phase I-II) treatment, and selection effects were most negative in
these communities. Our results highlight the importance of soil
microbial communities in driving positive plant diversity effects, and
future rainfall changes can cause complicated patterns in the
biodiversity-ecosystem functioning relationships through soil microbial
legacy.