Data from: Drought mildly reduces plant dominance in a temperate prairie ecosystem across years

1. Shifts in dominance and species reordering can occur in response to
global change. However, it is not clear how altered precipitation and
disturbance regimes interact to affect species composition and dominance.
2. We explored community-level diversity and compositional similarity
responses, both across and within years, to a manipulated precipitation
gradient and annual clipping in a mixed-grass prairie in Oklahoma, USA. We
imposed seven precipitation treatments (five water exclusion levels [-20%,
-40%, -60%, -80%, and -100%], water addition [+50%], and control [0%
change in precipitation]) year-round from 2016-2018 using fixed
interception shelters. These treatments were crossed with annual clipping
to mimic hay harvest. 3. We found that community-level responses were
influenced by precipitation across time. For instance, plant evenness was
enhanced by extreme drought treatments, while plant richness was
marginally promoted under increased precipitation. 4. Clipping promoted
species gain resulting in greater richness within each experimental year.
Across years, clipping effects further reduced the precipitation effects
on community-level responses (richness and evenness) at both extreme
drought and added precipitation treatments. 5. Synthesis: Our results
highlight the importance of studying interactive drivers of change both
within vs. across time. For instance, clipping attenuated community-level
responses to a gradient in precipitation, suggesting that management could
buffer community-level responses to drought. However, precipitation
effects were mild and likely to accentuate over time to produce further
community change.