Data from: Drivers of plant community (in)stability along a sea-inland gradient

Global change pressures are highlighting the need to better understand the
mechanisms driving the temporal stability of natural communities under
different environmental conditions. There is ample evidence that species
richness helps communities to withstand environmental fluctuations and
stabilise over time. However, it is still debated whether richness
promotes stability through the diversity of species functional traits,
phylogenetic lineages, and ecological strategies in the community or
because of the likelihood of including stable species. Further, it is
unclear whether the positive effect of diversity on stability is
maintained in conditions of strong environmental fluctuations (e.g.
frequent disturbances and stress).  To address these questions,
we analysed long-term monitoring data of 84 permanent plots in coastal
dune plant communities distributed along a gradient of natural stress and
disturbance, with communities closer to the sea subject to greater stress
and more frequent disturbances. Specifically, we used structural equation
models to disentangle the relative influence of the environmental gradient
and the different diversity components (species richness, functional and
phylogenetic diversity; SR, FD, and PD), as well as of the dominant
ecological strategy (captured by species lifespan) on community stability,
through their effect on two key stability mechanisms (population stability
and species asynchrony).  We found that the sea-inland
environmental gradient was the main driver of stability mechanisms. Stress
and disturbance decreased both population stability and species
asynchrony, but also reduced species richness, which thus exerted a
stabilising effect only on the communities in more favourable
environmental conditions.   Surprisingly, we did not
find an effect of FD and PD on community stability, neither directly nor
via asynchrony. However, the dominance of perennial species mitigated the
instability generated by stress and disturbance. Perennial species were on
average more stable than annuals and displayed a wider range of species
fluctuations, including compensatory dynamics among species (i.e.
asynchrony).   Synthesis: Overall, our results highlight
the importance of accounting for the environmental context when examining
mechanisms of community stability. Species richness remains a useful
direct predictor of community stability. Species ecological strategies,
like the acquisitive-conservative trade-off connected to lifespan,
however, should also be routinely considered as drivers of both population
stability and compensatory dynamics.