Aspen elk and fire in the Rocky Mountain national parks of North America

摘要: Trembling aspen (Populus tremuloides) forests in the Rocky Mountains are an indicator of ecological conditions because they have maintained their presence for thousands years through vegetative reproduction, and these communities high biodiversity. Aspen can be tied to ecosystem condition a 4-level trophic model that links humans, wolves (Canis lupus), elk (Cervus elaphus), processes predationf herbivory, burning! differential wildlife responses humans. We used compara- tive study research literature historic photographs evaluate change over time 6 Mountain national parks Canada United States: Jasper, Banff, Yoho, Kootenay, Yellowstone, Mountain. Across all parks, has consis- tent increased browsing by ungulates decreased frequency fire. Al- though was historically vigorous today most stands decline. Trees intermediate mature age (60-120 old), browse off new suck- ers before reach 2 m height. Fire, combined with browsing, hindered regen- eration aspen. The exception this pattern is northern Jasper National Park where densities appear been reduced 1970s, regenerated. found gradient increasing human-caused changes parks: (1 ) frequent fires low density regulated wolves, other predators (i.e., parks); (2) current patches density, displaced human land use, within matrix mod- erate present Banff na- tional (3) recent condltions inside absent, very competition food Yellowstone 1995); (4) potential future conditions, use around displaces car- nivores reduces hunting, occurs throughout landscapes. As- pen regenerate well areas some moderate density; however, does not heights >2 m, burning accelerates clone deterioration. Our recommendations park managers restore carnivores, fire control uses displace carnivores.