Data from: Climate and local environment structure asynchrony and the stability of primary production in grasslands

Aim: Climate variability threatens to destabilize production in many
ecosystems. Asynchronous species dynamics may buffer against such
variability when decreased performance by some species is offset by
increased performance of others. However, high climatic variability can
eliminate species through stochastic extinctions or cause similar stress
responses among species, reducing buffering. Local conditions, such as
soil nutrients, can further alter production stability directly or by
influencing asynchrony. We test these hypotheses using a globally
distributed sampling experiment. Location: Grasslands in North America,
Europe and Australia. Time period: Annual surveys over five-year intervals
occurring between 2007 and 2014. Major taxa studied: Herbaceous plants.
Methods: We annually sampled per-species cover and aboveground community
biomass (net primary productivity; NPP), plus soil chemical properties, in
twenty-nine grasslands. We tested how soil conditions, combined with
precipitation and temperature variability, affect species richness,
asynchrony and temporal stability of primary productivity. We used
bivariate relationships and structural equation modeling to examine
proximate and ultimate relationships. Results: Climate variability
strongly predicted asynchrony, whereas NPP stability was more related to
soil conditions. Species richness was structured by both climate
variability and soils, and in turn increased asynchrony. Temperature and
precipitation variability caused a unimodal asynchrony response, with
asynchrony lowest at low and high climate variability. Climate impacted
stability indirectly through its effect on asynchrony, with stability
increasing at higher asynchrony due to lower inter-annual NPP variability.
Soil conditions had no detectable effect on asynchrony but increased
stability by increasing mean NPP, especially when soil organic matter was
high. Main Conclusions: We found globally consistent evidence that climate
modulates species asynchrony, but that the direct effect on stability is
low relative to local soil conditions. Nonetheless, our observed
unimodal responses to temperature and precipitation variability
suggest asynchrony thresholds, beyond which there are detectable
destabilizing impacts of climate on primary productivity.