Healthy forests are better for wildlife


Note: This is a continuation of the previous edition of "Natural Resources Notebook."

Can productive, extractive management be made compatible with wildlife in achieving sustainability? The term "sustainable productive forest management" implies that it can by imposing constraints on specific operations of treatment to make them compatible with other uses - in this case, wildlife.

How each wildlife species fits into the overall scheme of things in an ecosystem, its niche, must be taken into account in determining constraints. A species' niche involves food sources and living conditions, such as nesting and cover for protection.

A management planning process that includes imposing constraints starts with defining objectives and strategy. It involves evaluating the case in terms of outcomes, both desired and unwanted, using optimization models in the process of choosing the most appropriate silvicultural system to be applied. This involves analyzing and comparing a range of management options. The outcomes of these options are evaluated through simulation.

Here again, shade tolerance is a factor in considering possible impacts. Silvicultural treatment ("silvics" refers to trees and forests; "silvi" as in "agri" culture) is different for stands made up of shade-tolerant and shade-intolerant species.

Intolerants need full sunlight to regenerate, survive and grow, leading to a quite different way to manage forest stands compared to the needs of shade-tolerant tree species. Intolerant tree species need sufficient exposure to sunlight, which means eliminating most of the forest stand, as in clear-cutting. Contrary to common belief, this is a sustainable management option.

Managing a forest for intolerants by opening the forest canopy to exposure for sunlight would have negative impacts on shade-tolerant stands, which reproduce, survive and grow in the shade of the forest canopy. In the latter, treatment can be less intensive, more gradual in maintaining a healthy room to grow environment for shade-loving trees.

The "sustainable" element in the term means that all impacts must be taken into account as a basis for imposing restrictions on management in general and on specific operations, such as tree felling, skidding, loading and road building. The potential impact is taken as a whole over a large area of forest on all components of the ecosystem, both plant and animal. Overall impact can be mitigated by having areas of sustainable, nonextractive forest management interlaced with productive units where tree cutting is allowed.

Evaluation of expected impacts of a treatment option, such as timber harvesting, can be done using simulation models in which a range of options can be tested in order to choose the best. The best means that clear objectives for a forest stand must be stated, which in turn depend on policy. Basically, this is what needs to be done in environmental impact evaluation.

Environmental impact analysis of thinning and timber harvesting, as a means of treatment to improve health, is a major part of management planning.

A healthy, vigorous (room to grow) forest, diverse in habitat (including gap-phase succession areas) and in species (high level of biodiversity) is better for wildlife than an unhealthy one.

This is the 158th article in the "Natural Resources Notebook"; the first 99 are in "Forest Power: Adventures in Ecology and Forest Management." A complete list can be found at Many are available online at Email


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