Climatic criteria for successful introduction of Quercus species identified by use of arboretum data.
Climate change is projected to have a major influence on forest tree populations and composition. Translocation of species outside their historic range has been suggested to maintain healthy forests and tree species. The introduction of exotic species into botanical gardens and arboretums worldwide demonstrates the ability of many trees to grow outside their natural habitat and may play an important part in avoiding climate driven extinction if grown in a matching climate. However, it remains to be determined which climatic factors are the most important predictors of climatic match. In this study we use information from the arboretum in Hørsholm, Denmark, to analyse differences in performance of translocated Oak (Quercus) and show how data from tree collections can be used to predict success of assisted migration. Our data included archive lists of georeferenced Northern hemisphere introductions of Quercus, and assessments of their survival and growth rates in nursery and the Hørsholm arboretum. Using logistic and linear regression we modelled the importance of different bioclimatic predictor variables for survival and growth rate. Several correlations were identified across the Quercus genus. Survival of Quercus species depended primarily on the temperatures at the origin, whereas growth on the other hand was more dependent on a match in precipitation. The negative correlations indicated that introductions were less successful from sites with higher temperatures and wetter conditions. The study demonstrates an approach to use historical data collected from arboreta and botanical gardens in climate change research. This new approach can provide useful information in relation to assisted migration for an array of poorly investigated species where this may be the only source of information.