Data from: Plant functional groups mediate drought resistance and recovery in a multi-site grassland experiment

1. Climate change predictions suggest that summer droughts will become
more intense and recurrent in Europe. While drought-induced reductions in
grassland primary productivity are well documented, the drivers behind
drought resistance (the capacity to withstand change) and recovery (the
capacity for recovery of function) of above- and belowground biomass
remain poorly understood. 2. Across eight grasslands differing in plant
community productivity (CP) we investigated the effects of summer drought
on plant and soil microbial variables, plant nutrient content and soil
nitrogen (N) availability. We examined the linkages between community
productivity, soil N, drought responses of plant and microbial communities
and relative drought responses of plant and microbial biomass. Plant and
microbial variables were recorded at the end of a three-month rainfall
exclusion period. Plant variables were also assessed during a 10-month
drought recovery period. 3. Experimental drought decreased plant biomass
and increased plant C:N ratios, but had no effect on total microbial
biomass across sites. Instead, drought caused shifts in plant and
microbial community structures as well as an increase in arbuscular
mycorrhiza fungi biomass. Overall, plant biomass drought resistance was
unrelated to community productivity or microbial community structure but
was positively related to drought resistance of forbs. 4. In the month
after rewetting, soil N availability increased in droughted plots across
sites. Two months post-rewetting, droughted plots had higher plant N
concentration, but lower plant N use efficiency. The short-term drought
recovery of plant biomass was unrelated to community productivity or soil
N availability, but positively related to the response of grass biomass,
reflecting incomplete recovery at high community productivity. Ten months
after rewetting, drought effects on plant biomass and plant N content were
no longer apparent. 5. Synthesis. Our results suggest that drought
resistance and recovery are more sensitive to plant community composition
than to community productivity (CP). Short-term recovery of plant biomass
may also benefit from increased soil N availability after drought and from
a high abundance of soil fungi in low productivity sites. Our findings
underline the importance of plant functional groups for the stability of
permanent grasslands in a changing climate with more frequent drought.