Forest Health and Silviculture

Forest health describes a forest condition. A healthy forest: is resilient to change. is characterized by biological diversity. provides sustainable habitats for fish, wildlife and humans A forest is unhealthy when certain agents of change upset the normal range of the natural dynamics in a forest. Some of these agents are wildfire, insects, diseases, site quality, wind, rain, ice, snow, floods, air pollution, temperature extremes, and poorly thought-out forest management practices.

Someof these agents of change include but are not limited to the following:

• Defoliating insects, such as spruce budworm and Douglas-fir tussock moth, eat the foliage of Douglas-fir and grand fir.
• Bark beetles, such as mountain pine, western pine and Douglas-fir beetles, attack stressed trees, boring into the bark and killing them.
• Dwarf Mistletoe, a parasitic plant which infects most coniferous species, including Douglas-fir, true firs, western larch, and lodgepole and ponderosa pine.
• Root diseases and other tree deforming organisms such as fungi, Armillaria root rot or laminated root rot, attack the roots of trees. Douglas-fir, grand fir and some pines are susceptible to these diseases.
• Wildfire, a normal part of many forest systems, but a catastrophic factor when high levels of ground fuels and dense trees allow consumption of whole forests.
• Adverse environmental conditions such as drought, ice storms, heavy snows, and other extreme climatic conditions predispose forests to catastrophic attacks by other agents.
• Human activities, which include some management practices - such as harvesting the best trees and leaving the weaker trees or species, i.e. the high graded plot in the NC block - can adversely affect forest health.

Agents of change will always be present. There are, however, management practices which can be used to improve forest health problems. These practices require long-term commitments.

For short-term protection of high value areas, spraying pesticides may reduce defoliating insect populations. However, spraying will not cure the problems of overstocked or stressed forest stands nor will it address bark beetle epidemics, mistletoe, or root diseases. For these problems, there are silvicultural management options.

Silvicultural Treatments

Catastrophic Fire:

Over time, many of the natural processes that influence forest landscapes have been dramatically altered. One of these changes was the exclusion of fire in many lowland ownerships. As fires were suppressed, dense forests grew where more open stands once stood. These dense forests are now comprised of trees more tolerant of shade than pine and other, less shade tolerant species - and much less fire and pest resisitant. Increasing the amount of older ponderosa pine and larch in the forest (where ecologically appropriate) will reduce damage caused by wildfire because these species are better adapted to survive fires.

Insects and Disease:

At the Sherwood Creek Demonstration Forest some blocks have been subjected to silvicultural treatments that favor hearty, healthy trees, thus reducing the forest's susceptibility to insects and diseases.

• Where appropriate, planting pine and larch after harvesting or thinning existing stands to favor these species can, over time, restore the health of the forest, as evidenced in the NE and SE management blocks.
• Controlled fire, when included in the forest's life cycle, helps promote a pest-resistant condition. Fire is a part of the natural disturbance process in this forest, and is being reintroduced to three of the treatment plots on the south side of the NC demonstration block
• The NE block shows remnants of a large root rot area. This area is being managed to reduce the impact of root rot on the remaining trees by planting more tolerant species, like white pine and western larch.

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