What is a forest pest?

A forest pest is any living organism that can cause harm to plants, trees or forests, or to forest products. Such organisms may be insects, spiders, mites, nematodes, fungi, bacteria, viruses, weeds (including woody weeds), mammals and other wildlife, and parasitic plants such as mistletoe.

Serious pest infestations can undermine years of management effort and greatly hamper the achievement of forest management objectives. Pests can adversely affect tree growth, vigour and survival and reduce the yield and quality of wood and non-wood products. Damage caused by pests can degrade wildlife habitat, thereby reducing local biodiversity, and can also have major negative impacts on recreational, aesthetic and sociocultural values. The presence of certain pests may result in the curtailment of reforestation programmes or require a change in the tree species used, and it may require the clearfelling of large areas of forest dominated by infested trees.

Measures to protect forests from pests are an integral part of sustainable forest management (SFM). Effective forest pest management (often called “integrated pest management” – see In more depth) involves:

1. maintaining the health of forests;
2. managing native pest disturbances that threaten forests; and
3. preventing the entry and spread of non-native species into new areas.