Modeling climate change effects with provenance test data.

Provenance tests of forest trees, which were originally intended to identify suitable seed sources for planting at different locations, provide valuable data for assessing the response of populations to environmental change. Environmental differences between the location of origin and the planting (test) site have been calculated by principal component analysis and termed ecological distance. Based on ecological distance values, the growth response of tree populations can be modeled as a function of the test site macroclimate. These models can then be used to predict the effects of climatic change on growth and survival. The growth response model predicts that increasing annual mean temperatures will result in accelerated growth if precipitation is sufficient, but only within the limits characteristic of the species. At the southern limits of distribution, growth and competitive ability of the species will decline, leading to successional changes.