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Planted forest health: the need for a global strategy

Mike Wingfield: Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria

<div>Planted forests, especially those of non-native tree species have been dramatically expanded in extent during the course of the past 100 years. This has occurred to meet a growing need for timber products including paper, packaging and most recently wood-based chemicals. Non-native trees separated from their natural enemies are typically highly productive in the early stages of establishment. This situation changes as pests (including insects and pathogens) are accidentally introduced into the new plantation environments. There are also growing numbers of examples where pathogens native to these new environments undergo host jumps to infect the non-native trees or where pathogens have changed genetically to infect trees previously not susceptible to them. Some of these novel pathogens emerging after host jumps are now also causing devastating epidemics on native trees in forests and woody ecosystems. In addition, a bridgehead effect, where invasive pest populations serve as the source for further introductions into new areas, has emerged as a major driving force in the increased rate of emergence of new pest threats. It is increasingly clear that many factors relating to the patterns and processes underlying pest epidemics in planted forests are poorly understood and that their importance has been underestimated. A global strategy, including enhanced research efforts, international collaboration and significantly improved quarantine processes will be required to deal with this problem. This is not only to ensure the sustainability of planted forests, but also the health of crucially valuable natural forest ecosystems.</div>