Differences in forest tree populations' responses to changes in climate: What have we learned from modeling provenance tests data
A multitude of provenance tests have demonstrated that populations’ adaptation to the local environment is common in forest tree species. For such species, the growth responses to a changing climate are likely to be population-specific. Increased interest in understanding how different populations would respond has led to a renewed interest in provenance tests as climate change experiments. Analyses of these have data demonstrated that fast-growing populations originating in mild environments are likely to be negatively affected by a warming climate sooner than populations originating in cold or low-resource environments. This study reviews and synthesizes work published since the early 1990’s, presenting summaries from all species modeled and identifying climate variables that are reported as relevant in shaping intraspecific differentiation in most of the studies. A discussion of common findings and suggestions for improvement in modeling methodology is presented.
Populations’ growth responses to climate change have been modeled using provenance test data for more than 20 forest tree species. In general, models indicate intra-specific differentiation, populations reaching different maximum height growth and achieving these maximums under different environmental conditions. Climate variables reflecting the coldness of the environment commonly show the strongest clines with growth and other traits. The majority of the studies indicate a strong interaction between populations’ growth and test environment. Modeling methodology can be improved by ensuring that all effects generated by the experimental design are accounted for. This should lead to a better understanding of the sources of uncertainty, which in turn can serve as focus of future research. Models of populations’ growth responses to changes in climate can aid in seed source selection for reforestation and restoration efforts under a changing climate as demonstrated by several of the reviewed studies.