Amplitude and timescale of metacommunity trait-lag response to climate change

Climate change is altering the structure and functioning of communities 1. Trait-based approaches are powerful predictive tools that allow consideration of changes in structure and functioning simultaneously 2, 3. The realised biomass-weighted trait distribution of a community rests on the ecophysiology of individuals, but integrates local species interactions and spatial dynamics that feed back to ecosystem functioning. Consider a response trait that determines species performance (e.g. growth rate) as a function of an environmental variable (e.g. temperature). The change in this response traits distribution following directional environmental change integrates all factors contributing to the communitys response and directly reflects the communitys response capacity 3. Here we introduce the average regional community trait-lag (TLMC) as a novel measure of whole-metacommunity response to warming. We show that functional compensation (shifts in resident species relative abundances) confers initial response capacity to communities by reducing and delaying the initial development of a trait-lag. Metacommunity adaptive capacity in the long-term, however, was dependent on dispersal and species tracking of their climate niche by incremental traversal of the landscape. With increasing inter-patch distances, network properties of the functional connectivity network became increasingly more important, and may guide prioritisation of habitat for conservation.