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.

The dataset contains site information, years of survey and climate data, and summary data for species asynchrony, stability, climate means and variability. Most data are processed to provide the indices and summary statistics used in the published paper, and allow reproduction of the published figures and statistics reported. Raw data containing annual species abundances and monthly climate measurements for each site and plot are available from the NutNet database (https://nutnet.org/).