Spatial synchrony, the tendency for temporal fluctuations in an ecological variable to be positively associated in different locations, is a widespread and important phenomenon in ecology. Understanding of the nature and mechanisms of synchrony, and how synchrony is changing, has developed rapidly over the past two decades. Many recent developments have taken place through the study of long-term datasets. Here, we review and synthesize some important recent advances in spatial synchrony, with a focus on how long-term data have facilitated new understanding. Longer time series do not just facilitate better testing of existing ideas or more precise statistical results; more importantly, they also frequently make possible the expansion of conceptual paradigms. We discuss several such advances in our understanding of synchrony, how long-term data led to these advances, and how future studies can continue to improve the state of knowledge.

Foundation species recovery is often assumed to restore associated communities to their pre-disturbance state. However, community dynamics may differ due to species-specific responses, altered environmental conditions, or changes in biotic interactions that can override the influence of the recovering foundation species. In a 14-year experiment, we studied the loss and recovery of giant kelp and its associated rocky reef community. Alongside reference plots, we removed giant kelp for 6–7 years, then tracked recovery for another 6–7 years. After cessation of removal, giant kelp and community (understory macroalgae and sessile invertebrates) biomass rapidly converged on the reference condition. However, the composition of the community diverged from the starting point, indicating that recovery of community biomass can disguise species turnover in response to foundation species recovery. Our results highlight how stochastic forces can overwhelm the influence of foundation species to determine the structure of communities when recovering from disturbance.

Disturbances often disproportionately impact different vegetation layers in forests and other vertically-stratified ecosystems, shaping community structure and ecosystem function. However, disturbance-driven changes may be mediated by environmental conditions that affect habitat quality and species interactions. In a decade-long field experiment, we tested how kelp forest net primary productivity (NPP) responds to repeated canopy loss along a gradient in grazing and substrate suitability. We discovered that habitat quality can mediate the effects of intensified disturbance on canopy and understory NPP. Experimental annual and quarterly disturbances suppressed total macroalgal NPP, but effects were strongest in high-quality habitats that supported dense kelp canopies that were removed by disturbance. Understory macroalgae partly compensated for canopy NPP losses and this effect magnified with increasing habitat quality. Disturbance-driven increases in understory NPP were still rising after 5–10 years of disturbance, demonstrating the value of long-term experimentation for understanding ecosystem responses to changing disturbance regimes.