Treesearch

Although the Stand Prognosis Model has several stochastic components, features have been included in the model in an attempt to minimize run-to-run variation attributable to these stochastic components. This has led many users to assume that comparisons of management alternatives could be made based on a single run of the model for each alternative. Recent analyses have demonstrated that this assumption may often be incorrect. Several possible solutions are given, and the author recommends that in almost all applications of the Stand Prognosis Model it would be wise to make at least two or...

Hurricane Hugo passed over the Francis Marion National Forest on September 22, 1989, removing almost 75 percent of the overstory. The radically altered fuel bed presented new and formidable challenges to fire managers. Tractor-plows, the mainstay of fire suppression, were rendered ineffective. The specter of wind-driven escaped burns with no effective means of ground suppression prompted the State of South Carolina to ask for a 12-month voluntary ban on all prescribed burning in Hugo affected areas. Emergency federal funding was used to augment existing fire suppression capabilities,...

A study of Southern Appalachian backcountry hikers tested the hypothesis that recreationists with high experience levels would have greater differentiation of site attribute values when making recreation choices than would individuals with low experience. Contrary to cognitive development theory, a simulated laboratory choice study found that more experienced subjects employed fewer and broader attribute value categories than did their less experienced counterparts. This surprising finding might be explained by the nature of the judgment task. Cognitive development theory suggests that...

Over an 11-year period there was no net erosion from three trails in the Selway-Bitterroot Wilderness, Montana. Most individual trail segments experienced change, but deposition was slightly more common than erosion. Mean cross-sectional area decreased from 1,187 cm2 in 1978 to 1,155 cm2. Trail widening was more pronounced than trail incision. The lightly used South Fork Trail experienced more change than the more heavily used Big Creek Trail. Although these trail systems, taken as a whole, are relatively stable, deterioration does occur in certain places. One purposively located trail...

I studied relative abundances, foraging behavior, and foraging habitats of Nuttall's Woodpeckers (Picoides nuttallii# at three California locations. Population sizes at two areas in the foothills of the Sierra Nevada were larger than the population in the Tehachapi Mountains. These differences were attributed to habitat and weather differences. The two areas in the Sierra foothills had milder winters and contained large interior live oaks #Quercus wislizenii# and gray pines #Pinus sabiniana#, species used extensively by woodpeckers outside of the breeding season. The Tehachapi area...

The addition of more than 900 plots to the Daubenmire's original 181-plot database has resulted in a refinement of their potential natural vegetation-based land classification for northern Idaho. A diagnostic, indicator species-based key is provided for field identification of the eight climax series, 46 habitat types, and 60 phases. Recognized syntaxa are described by occurrence, environment, vegetation, and management implications.

Large tracts of wildland in North America have been set aside as wilderness areas and national parks. More than 200 million acres (88 million ha) of such lands have been formally designated in Canada and the United States (Eidsvik 1989). The primary goal of these designations is the preservation of undisturbed natural conditions and processes.

There are few documented cases of gallinaceous birds caring for offspring other than their own. Willow Ptarmigan (Lagopus lagopus) usually mate monogamously, with pairs remaining together throughout the breeding season, but they occasionally are polygynous (Hannon 1984, Martin and Cooke 1987, Martin 1989). If males are removed from monogamous pairs after breeding, replacement males may fill the openings and adopt the brood (Martin 1989). We observed four cases of apparent adoption by Merriam’s Wild Turkeys (Meleagris gallopavo merriami) during 1987, 1988, and 1989 while collecting data to...

In 1983 zinc phosphide, strychnine with prebait, and strychnine without prebait were applied to black-tailed prairie dog (Cynomys Zudovicianus) colonies in west central South Dakota. Short-term (four days later) and long-term (one year later) impacts of the rodenticides on Horned Larks (Eremophila alpestris) and other granivorous birds inhabiting prairie dog colonies were evaluated. Horned Larks and 49 other bird species were observed. Immediate impacts reduced Horned Lark relative densities 66% with strychnine only and 55% with prebaited strychnine. Zing phosphide caused no measurable...

A standard campsite model is proposed and then manipulated to examine the influence of individual variables on amount of vegetation loss. Amount of impact is influenced by amount of use, vegetation fragility, vegetation density, and the degree to which activities are concentrated spatially on the site. Degree of concentration also influences the importance of the other explanatory variables. Amount of use and vegetation fragility are equally important determinants of impact and are most Influential where activity concentration is low. The curvilinear relationship between amount of use and...