Treesearch

Past studies of quaking aspen in Rocky Mountain National Park suggested that the aspen population is declining due to intensive browsing by elk (Cervus elaphus). These studies were conducted in the elk winter range, an area of intensive elk impact. The elk summer range experiences less intense grazing pressure. We tested the hypothesis that impacts of elk would be greater in the elk winter range than the summer range with landscape-scale data from the Park. The detrimental effects of elk on aspen are highly localized and, at larger spatial scales, elk browsing does not seem to be influencin...

Sustaining forest productivity requires maintaining soil productivity. Management activities that decrease soil porosity and remove organic matter can reduce productivity. We determined effects of three levels of organic matter removal (OMR) and soil compaction on aspen regeneration and growth following winter harvest of aspen-dominated stands in northern Minnesota, western Upper Michigan, and northern lower Michigan. The OMR treatments were merchantable bole harvest (MBH), total tree harvest (TTH), and total woody vegetation harvest plus forest floor removal (FFR). Compaction treatments...

Elk-aspen foraging patterns may be influenced by cover type, distance from roads or trails, the type of user on road or trail (park visitor, human hunter, or predator), and two general states of aspen condition (open-grown or thicket). Pellet group and browse utilization transects in the Canadian Rockies showed that elk were attracted to roads used by park visitors and avoided by wolves, and that elk possibly avoided aspen and conifer patches near backcountry trails used by wolves. In high predation risk landscapes, aspen stands were dense, lightly browsed, and rarely entered by elk. As...

Aspen has been an ecologically important, though relatively minor, component of the Lake States (Michigan, Wisconsin, and Minnesota) forests for millennia. General Land Office records from the 1800s indicate that aspen comprised a small fraction of the region's eastern forests, but was more extensive on the western edge. Then Euro-American settlement in the 1800s brought land clearing, timber harvesting, and subsequent widespread wildfires that increased aspen-birch acreages considerably. Although aspen-birch acreage has declined since the 1930s, it remains the region's second most...

In the Blue Mountains of northeast Oregon, quaking aspen is on the western fringe of its range. It exists as small, scattered, remnant stands of rapidly declining trees. Although little is known about the historic distribution of aspen in Oregon, it is believed that stands were once larger and more widely distributed. Decline of the species is attributed to fire suppression and browsing pressure from large ungulates. A landscape approach to restoring aspen is taken using a variety of techniques. Among these are construction of large herbivore exclosures, prescribed fire, establishment of...

In Grand Teton National Park, a landscape-scale assessment of regeneration in aspen has assisted park managers in identifying aspen stands that may be at risk due to a number of interrelated factors, including ungulate browsing and suppression of wildland fire. The initial aspen survey sampled an estimated 20 percent of the park's aspen stands. Assessment of these data indicate an aging stand structure plus a parkwide impact of elk and ungulate browsing on aspen regeneration less than 2 m tall. While the use of prescribed fire and wildland fire use actions may stimulate aspen regeneration,...

Whitebark pine (Pinus albicaulis) is one of many North American white pine species (Pinus subgenus Strobus) susceptible to the fungal disease white pine blister rust (Cronartium ribicola). Blister rust has caused severe mortality (often reaching nearly 100 percent) in many stands of white bark pine north of 45° latitude in western North America. The rust is slowly moving south through the range of whitebark pine and other white pine species.

In 1883, when the Northern Pacific Railroad made its way through northern Idaho, western white pines dominated the moist, mid-elevation, mixed-species forests of the Inland Northwest between 2,000 and 6,000 feet. These majestic trees often lived to 350 years but could reach the ripe old ages of 400 and even 500 years. They were an integral part of the most productive forests in the region, providing habitat for a highly diverse mixture of organisms, from the smallest microbes to lichens, higher plants, and animals.

Fecal samples from 54 Gunnison's prairie dogs (Cynomys gunnisoni) from Albuquerque, NM were analyzed for the presence of coccidia and all were positive. They were then relocated to an abandoned prairiedog town on the Sevilleta Long Term Ecological Research (LTER) site. Six Eimeria species, E. callospermophili, E. cynomysis, E. pseudospermophili (new host record), E. spermophili, E. Iudoviciani and E. vilasi (new host record) were found in Albuquerque animals, but only 2 species, E. callospermophili and E. vilasi were present in relocated hosts. A significant (P < 0.05) reduction was seen...

Understanding the influence of environmental variation on population processes is a fundamental requisite for devising strategies that conserve species. A common tactic for conserving raptor populations is to maintain or manipulate habitat conditions that maintain or increase availability of prey species. A primary purpose of this investigation was to evaluate the hypothesis that Mexican spotted owls (Strix occidentalis lucida) could be conserved by manipulating microhabitat conditions that increased abundance of one or more common prey species. I evaluated this hypothesis by (1) determinin...