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ABSTRACT Global change drivers alter multiple components of community composition, with cascading impacts on ecosystem stability. However, it remains largely unknown how interactions among global change drivers will alter community synchrony, especially across successional timescales. We analysed a 22‐year time series of grassland community data from Cedar Creek, USA, to examine the joint effects of pulse soil disturbance and press nitrogen addition on community synchrony, richness, evenness and stability during transient and post‐transient periods of succession. Using multiple regression and structural equation modelling, we found that nitrogen addition and soil disturbance decreased both synchrony and stability, thereby weakening the negative synchrony–stability relationship. We found evidence of the portfolio effect during transience, but once communities settled on a restructured state post‐transience, diversity no longer influenced the synchrony–stability relationship. Differences between transient and post‐transient drivers of synchrony and stability underscore the need for long‐term data to inform ecosystem management under ongoing global change. 

Abstract Organisms that undergo a shift in ontogeny and habitat type often change their spatial distribution throughout their life cycle, but how this affects population dynamics remains poorly understood.We examined spatial and temporal patterns inAedes nigripesabundance, a widespread univoltine Arctic mosquito species (Diptera: Culicidae), hypothesizing that the spatial distribution of adults would be closely tied to aquatic habitat.We tracked adult densities ofA. nigripesnear Kangerlussuaq, Greenland using emergence traps, CO₂‐baited traps, and sweep‐nets.In back‐to‐back years of sampling (2017 and 2018) we found two‐fold variation in overall abundance.Adults were spatially patchy when first emerging from aquatic habitats but within a week, mean capture rates for host‐seeking adult females were similar across locations, even in places far from larval habitat.Daily variation in mosquito captures was primarily explained by weather, with virtually no mosquito activity when temperatures averaged less than 8°C or wind speeds exceeded 6 m/s. Gravid females (3% of resting adults) were spatially patchy on the landscape, but not always in the same places where most adults emerged.The spatial distribution of adults is quickly uncoupled from the spatial distribution of larvae becauseA. nigripesfemales may disperse far from their natal habitats in search of a blood‐meal and high‐quality oviposition habitat. 8. This research highlights the value of studying ecological processes that act at disparate life stages for understanding the population biology of organisms with complex life cycles.