The observed patterns in natural communities are products of historical processes and conditions. This is particularly true for long-lived organisms, such as trees and corals, where past conditions can continue to affect observed demographic and ecological patterns centuries later. This has two implications. First, the temporal scale that our theories of community change operate at (over multiple generations) is not matched by the temporal scale of many observational datasets. Second, predicting future changes of a community using current conditions is challenging without knowing the historical trajectory. Currently, modern trends are most often benchmarked against theoretical null models.
In this talk I use a millennial-scale time-series dataset of nine coral communities sampled from uplifted reef terraces along 35 km of the Papua New Guinean coast to highlight trends in standing richness (alpha diversity) and turnover (temporal beta diversity) over time and across spatial scales, incorporating both taxonomic and functional data. These communities date from 9,000 to 6,000 years ago, an ideal time period for examining community dynamics, as reefs were continually accreting to match sea level rise, and human impacts were low. These long-term trends help to inform our understanding of how current community patterns differ from those of the recent geologic past, with potential to improve our prediction of both anthropogenic impacts and future community trajectories.