Changing forest communities: Role of tree resistance to insects in insect invasions and tree introductions

Abstract

Changes in forest communities are the consequences of two main phenomena: the plantations of exotic tree species in new environments, the commercial and tourist exchanges bringing exotic living organisms, especially insects, in new ecosystems. An important general consequence is the modification of the functioning of the forest ecosystems, and in particular a modification of the tree-insect relationships at the ecosystem level. Tree-insect relationships are changing through insect access to new resources (novel hosts), changes (often indirectly) in quality and quantity of the existing resources (native hosts), and change of the biotic environment (other than host plant) of the insect (new competitors, parasites and predators). The results are modifications of existing tree-herbivore relations (without host shifting), as well as building of new associations (host shifting). In these conditions, the questions are: What are the risks for both native forests and exotic plantations? How can pest management adapt to protect forest resources? © Springer Science+Business Media B.V. 2008.