Spatial, environmental and functional distances among temporal ponds attenuate synchronization, stabilizing plant richness and biomass dynamics

Abstract

Synchronized dynamics reduces ecosystem stability, as local variations in biomass or richness are directly propagated to variations in metacommunity dynamics. Synchronization of biodiversity dynamics can occur due to dispersal among communities and similar responses of different communities to correlated environmental variations, the Moran effect. This congruent response of different communities to environmental dynamics depends on their similar functional composition, which is determined by the similarity in local conditions and the spatial distance between them. In a metacommunity of 51 temporary ponds that were surveyed for 14 years, we evaluated the existence of synchronized dynamics in plant richness and biomass among communities, and their association with temporal stability. A wide range of dynamics was observed, from asynchronous to synchronous rhythms. Path analysis based on Mantel tests supported the decoupling of richness dynamics by the geographic, environmental, and functional distances between pairs of communities. Only the functional distance between communities weakly affected biomass synchrony. Synchrony in both richness and biomass between communities reduced the stability of the biomass dynamic. While synchrony in richness reduced its stability, synchrony in biomass enhanced the stability in richness dynamic. The role of rare species in richness dynamics and of dominant species in biomass dynamics may explain the observed discrepancies. Consequently, the size of metacommunities (the spatial extent and number of local communities), spatial heterogeneity, and functional diversity promote ecosystem stabilization by the mechanisms evidenced here. Climate change, environmental homogenization and landscape fragmentation may drive the synchronization and destabilization of biodiversity dynamics.