Historical and Anticipated Changes in Forest Ecosystems of the Inland West of the United States

Abstract

Euro-American settlement of the Inland West has altered forest and woodland landscapes, species composition, disturbance regimes, and resource conditions. Public concern over the loss of selected species and unique habitats (e.g., old-growth) has caused us to neglect the more pervasive problem of declining ecosystem health. Population explosions of Wees, exotic weed species, insects, [Hawonh co-indemng cnuy noel: "H~storeal and Antlclptcd Changes m Forest Ecosystems of rhc Inland Wcrt of rhc Un~ted Slates." Covlnnton. W. Wallax el al Cppubllshcd s~muhaJvously m lhc Journnl of Susroinable Farrsfry (Thc ~a k o r ( h Rcss, I n .

Fire and aquatic ecosystems of the western USA: current knowledge and key questions

“…The potential for large fires emerges as much from the continuity of high fuel levels that now exist across contiguous forest types as from the expansive area affected by forest changes (Covington et al, 1994;Skinner and Chang, 1996;Hessburg et al, 2000). By working strategically and concentrating on accessible sites, it may be possible to break up high-risk fuel continuity.…”

“…By working strategically and concentrating on accessible sites, it may be possible to break up high-risk fuel continuity. Because forest changes important to fire and fuels management are most strongly associated with lands that have been previously roaded and intensively managed in the past (Covington et al, 1994;Huff et al, 1995;Hann et al, 1997;Hessburg and Agee, this issue), few new roads may be needed (USDA, 2000). Roads have caused some of the most chronically damaging management impacts on aquatic ecosystems to date (Lee et al, 1997;Jones et al, 2000;Trombulka and Frissell, 2000;.…”

“…Fire was arguably the most important forest and rangeland disturbance process in the western USA for many millennia (Covington et al, 1994;Hessburg and Agee, this issue). Along with insects, diseases, and weather disturbances, fires were as much a part of the western landscape as the plant and animal species that lived there.…”

Fire regimes and forest structure in the Sierra Madre Occidental, Durango, Mexico

“…Disturbance regimes of frequent, low-intensity fires are a keystone ecological process (sensu Holling, 1992) regulating the density, species composition, dead woody biomass, and forest floor structure of western long-needled pine ecosystems in North America (Weaver, 1943(Weaver, , 1951Cooper, 1960;Covington et al, 1994;Arno et al, 1995;Swetnam and Baisan, 1996). These long-needled pines (Pinus ponderosa, P. durangensis, P. engelmannii, P. arizonica, P. jeffreyi, P. washoensis, and others) form a closely-related ecological group in the section Ponderosae with thick bark, insulated buds, and high capability to recover from crown scorch, all of which are considered adaptations to frequent fire (Conkle and Critchfield, 1988;McCune, 1988;Barton, 1993).…”

“…Fire ecology studies in the coniferous forests of the southwestern United States have shown that frequent fire played a key ecological role in these ecosystems by maintaining open, park-like forests of fire-adapted species, controlling tree populations, limiting accumulation of dead woody biomass and deep forest floors, cycling nutrients stored in dead organic material, and encouraging herbaceous production (Weaver, 1951;Cooper, 1960;Biswell, 1972;Covington and Moore, 1994;Covington et al, 1994;Swetnam and Baisan, 1996). Regimes of frequent, low-intensity fire were disrupted throughout the southwestern United States between 1880 and, 1900, however, by heavy grazing of domestic animals, logging, and fire suppression associated with Euro-American settlement of the region (e.g., see Cooper, 1960;Swetnam and Baisan, 1996;Covington et al, 1994).…”