Exploiting temporal variability to understand tree recruitment response to climate change

Much work is being done in the field of plant responses to climate change, where manipulative experiments (e.g., soil warming, elevated CO2) and correlative approaches (e.g. climate envelopes) are the norm. However, we ecologists are largely failing to report on the biggest experiment on climate change: the last few decades of global warming and rising atmospheric CO2. Plants and other organisms have already been responding to changing conditions. Long-term data are then our best bet to report the effects of climate change in natural communities. Global trends together with the annual variability in climatic constitute an invaluable source of information to base our inferences of vegetation change under future conditions.

That is what we attempted with our work (Ecological Monographs 77:163–177). By combining seed rain, seed bank, and germination dynamics with long-term environmental data within a heterogeneous landscape, we estimated how recruitment of the dominant tree species is affected by ten years of climatic variability. Reponses of contemporary forests to current climate are possibly the best indication of climate sensitivity. Our process-level approach, based on actual climate changes in natural settings, indicates that climate impacts will be complex, and only by employing a comprehensive approach were we able to discern each species response to climatic variability. Some of our results contradict previous predictions based on climate envelopes, but it is by comparing the two approaches where we can learn the most.

Contributed by Inés Ibáñez, Duke University