Environment of Idaho

The environment of Idaho is rich in ecological diversity. Major forest ecosystems include grand fir-Douglas fir forest, cedar-hemlock-pine forest, Douglas fir forest, western ponderosa pine forest, and western spruce-fir forest. While the northern part of the state is dominated by forests, most of the southern part of the state is covered by sagebrush steppe, interspersed with islands of desert and saltbush-greasewood shrublands.

Many areas in the state are nearly pristine and include some of the largest areas in the United States without paved roads.

Significant fish resources include salmon and steelhead.

Fire plays an important role in several ecosystems, including sagebrush steppe, western juniper woodlands, and ponderosa and lodgepole pine. In many of these ecosystems, fire suppression and other land use policies have resulted in significant changes in forest composition and structure.

In sagebrush steppe, a greater frequency of fires in the last 50 years has resulted in invasion by annual grasses such as cheatgrass and medusahead. In western juniper woodlands, continued grazing and 50 years of attempted fire exclusion have allowed juniper expansion to continue unchecked. Historically, frequent, low-intensity surface fires perpetuated park-like conditions in ponderosa pine stands. Today, after 60 years of fire suppression, many of these forests, along with lodgepole pine forests, have high densities of trees, are plagued by epidemics of insects and diseases, and are subject to severe stand-destroying fires. Significant changes are also occurring in whitebark pine populations of high-elevation forests. In northern Idaho, stands have decreased by anywhere between 50 and 100%, due in part to fire suppression and white pine blister rust, a non-native fungus that has defied control. Fewer than 1 in 10,000 trees is resistant.

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