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The maintenance of forest health is a critical aspect of sustainable forests. Forest health is an 'umbrella' term covering a variety of issues, ranging from yield losses associated with pests and disease to the ability of a forest to fulfil all its expected functions. Research is concentrating on the development of a working definition of forest health so that managers are able to determine the state of health of their forests. Air pollution: In many areas, air pollution occurs at sufficient concentrations to cause acute (short-term) or chronic (long-term) injury to forest plants. Efforts have been made to reduce emissions of many pollutants, especially sulphur dioxide, hydrogen fluoride and heavy metals. However, other pollutants, such as ozone, appear to be becoming more widespread. In British Columbia, pollution damage has occurred around smelters and industrial plants, such as at Trail and Kitimat. It has also occurred in association with gas-flaring events in north-eastern British Columbia.

Research Area: Forest Health

In the Fraser Valley, ozone is a potential problem, and concentrations are such that adverse effects on forest species can be expected. To date, there has been very limited research on this subject, despite the potential of ozone to cause marked (more than 10%) reductions in the annual growth of trees over large areas.

Air pollution:

In many areas, air pollution occurs at sufficient concentrations to cause acute (short-term) or chronic (long-term) injury to forest plants. Efforts have been made to reduce emissions of many pollutants, especially sulphur dioxide, hydrogen fluoride and heavy metals. However, other pollutants, such as ozone, appear to be becoming more widespread. In British Columbia, pollution damage has occurred around smelters and industrial plants, such as at Trail and Kitimat. It has also occurred in association with gas-flaring events in north-eastern British Columbia. In the Fraser Valley, ozone is a potential problem, and concentrations are such that adverse effects on forest species can be expected. To date, there has been very limited research on this subject, despite the potential of ozone to cause marked (more than 10%) reductions in the annual growth of trees over large areas.

Pathogens: The maintenance of a healthy forest is a central tenet of sustainable forest management. Unfortunately, while superficially attractivee, the human concept of health is very difficult to apply to a forest. For example, in view of the biological need of coarse woody debris in a forest, how many dead trees should there be in a forest? In the past, forest health has been concerned purely with damage to trees caused by biotic (such as insects and disease) and abiotic (such as wind and frost) factors. More recently, it has included a whole range of issues related to the integrity and stability of the forest ecosystem, making it much more

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