Ashy Metasedimentary Hills and Mountains 30-45" PZ Frigid Western Bitterroot Foothills

Description

This state with extended fire intervals turns into an all aged western redcedar stand with some grand fir present. Most understory regeneration is western redcedar again with some grand fir. Stand replacing fires start off in the herb/shrub stage with many species of shrubs potentially occupying the site. Shrubs include Douglas maple, serviceberry, snowbrush ceanothus, redstem ceanothus, snowberry, and ninebark. Tree regeneration is variable depending on available seed source. A host of seral species can establish including western larch, Douglas-fir, ponderosa pine, lodgepole pine, and western white pine (limited due to blister rust). Cedar and grand fir can also establish, but will sit underneath the seral species until released. Severe fires can cause soil degradation causing sites to remain in shrubs for long periods preventing tree establishment. With successful tree regeneration a mix of seral tree species can occupy the stand or in some cases, a single species like western larch will dominate the stand. These stands go into the stem exclusion phase with tree to tree competition. Understory vegetation will be sparse. As these stands mature mixed severity fires create a mosaic of stand structure and species composition with a combination of seral species and shade tolerant cedar and grand fir.
Sites on midslopes are more likely to burn more intensely than lower slopes due to a “thermal belt” condition with lower slopes being cooler and midslopes warmer and drier in summer conditions.

Submodel

Description

Severe fires change reference state to a shrubfield site. No tree regeneration due to shrub competition and soil conditions. Major shrubs include snowbrush and redstem ceanothus, serviceberry, ninebark, Scouler willow, elderberry species, snowberry, spirea, and Douglas maple

Submodel