Genomic demography predicts community dynamics in a temperate Montane forest

Species population sizes fluctuate over time, and these temporal dynamics play a key role in maintaining biodiversity. While multiple modeling approaches have been developed to characterize fluctuations in forest tree species abundances, the data required to parametrize these models from scratch are substantial. Here we introduce a novel approach to modeling population fluctuations on decadal timescales by relating community-level dynamics to population-level patterns encoded in plant genomes. Using a single genomic snapshot to generate contemporary effective population size estimates in a temperate montane forest, we accurately predict fluctuations across three censuses. Our approach opens the door for the use of genomic demography to parametrize multispecies community models in ecology and shows that population genomic data can provide accurate predictions for ecological dynamics.