Summary

Non-native species introductions have caused biodiversity loss worldwide, yetit is unclear how temporal diversity patterns vary across native and non-nativecommunities, and what mechanisms control their respective dynamics andassembly. Using a unique 12-year time series dataset of arthropods sampled inforest fragments on Terceira Island, we observed no systematic species lossesbut steady temporal β-diversity (Sørensen dissimilarity based on speciespresence–absence) for non-native, native endemic, and native non-endemicassemblages. However, native endemics and non-endemics showed an overallincreasing trend in Bray–Curtis dissimilarity (incorporating speciesabundances), with many previously abundant native species becomingprogressively rarer. By constructing neutral models, we accurately predictedtemporal diversity patterns for non-natives but not for native endemics andnon-endemics, displaying their divergent temporal dynamics. These resultsindicate that non-native assemblages are more consistent with stochasticsource-sink mass effect dynamics, while neutral drift interacting withnon-natives and/or environmental changes might drive native assemblagedynamics.