Compensatory dynamics, overyielding and statistical averaging are mechanisms promoting the temporal stability of natural
communities. Using the model of European intertidal rocky shore assemblages and collating 17 datasets, we investigated
how the strength of these stability-enhancing mechanisms varies with latitude and how it can be altered by the loss of
habitat-formers (e.g. canopy-forming macroalgae). Community stability decreased with increasing latitude, mostly as a
consequence of a greater synchronization of species fluctuations. Statistical averaging and overyielding (i.e. richness effect)
promoted stability, but their strength did not vary with latitude. An experimental removal of macroalgal canopies caused a
strengthening of the statistical averaging effect that was consistent across the latitudinal gradient investigated. Nonetheless,
the loss of canopies depressed stability by enhancing the synchronization of species fluctuations on southernmost shores,
while it had weak effects on shores at higher latitudes. Variation in life-history traits among canopy-forming species and/
or in prevailing environmental conditions across a gradient of latitude could underlie variable effects of habitat-formers on
species fluctuations. Our study shows 1) that the stability of intertidal assemblages and strength of compensatory dynamics
varies with latitude, 2) that canopy-forming macroalgae, exerting a strong control on understorey species, can influence the
strength of compensatory dynamics and 3) that biological forcing (i.e. facilitation) can be as important as environmental
forcing in enhancing the synchronization of species fluctuations.
