Professor Utah State University Logan, UT, United States
Abstract: Ecosystem function in the face of climate change is maintained by processes that vary in the timescales over which they occur. While fast processes such as physiological acclimation and phenological plasticity may keep up with the pace of current climate change, slower processes such as community turnover and evolutionary adaptation require more time. This lag of slow processes is likely to result, increasingly, in climate-ecosystem disequilibria as anthropogenic climate change progresses. Climate disequilibrium can be thought of as the difference between the optimal climate conditions in which an ecosystem can maximize function and the actual climate that the ecosystem experiences. Consequently, understanding and anticipating acclimation lags is important to management efforts that seek to maintain ecosystem function.
While climate disequilibria in the context of species composition have been studied in many systems, the functional consequences of those structural disequilibria remain poorly understood. Here, we develop and test a conceptual and mathematical framework to link theory about community climate niches to empirical time-series datasets that track ecosystem function. We do this by first presenting a method to estimate the timescale of ecosystem acclimation. Using a simulated timeseries dataset of community composition, we find that we are able to quantify acclimate lags by relating inter-annual climate variation to differenced community-level niche changes. Second, we explicitly connect acclimation lags to ecosystem function. We find that functions including primary productivity are responsive to the magnitude of climate-ecosystem disequilibrium. These advances allow us to leverage empirical remotely sensed datasets to determine under what circumstances and how quickly function in various ecosystems will decline and recover following rapid climate change.
