Treesearch

When three rodenticide treatments - zinc phosphide (prebaited) and strychnine (both with and without prebait) - were evaluated, zinc phosphide was the most effective in reducing active burrows of prairie dogs; but, it also resulted in a reduction in deer mouse densities. One month after treatment, counts of fecal pellets of eastern cottontails were greater on areas treated with strychnine without prebait than on sites treated with zinc phosphide. Eight months after treatment, no differences could be detected among rodenticides for either leporid. Horned lark densities were reduced 61% on...

Small mammals regarded as "pests" should not be viewed separately from other components in the ecosystem. Small mammals have significant influences on vegetation and soils, exert predatory pressure on other animals, and provide food for predators. Future management efforts should include consideration of these diverse influences.

We analyzed a data set constructed from functionally unrelated, easily collected observations (e.g., meat, stock, and liquor prices) around Fort Collins, Colorado, using principal components analysis (PCA), canonical correlation analysis (CC), and discriminant function analysis (DFA). Each produced seemingly significant results and suggested strong relationships between the variables measured. We suggest that multivariate techniques can provide invalid inferences when used with data containing no relationships. We question the use of these techniques in studies of wildlife habitat.

Prescribed burning beneath standing timber is widely used to accomplish objectives such as preparing land for reforestation, reducing fuels, improving livestock range, and modifying wildlife habitat. Such burning is usually guided by written plans that set forth general objectives and a firing pattern to accomplish them. The plan typically specifies acceptable levels of mortality in standing trees and describes desired fire behavior, particularly flame length. This article offers two nomograms to facilitate effective planning and successful burning. One nomogram is intended for estimating...

Habitat types and community types and their phases for the major forest tree species in the Rocky Mountain and Intermountain regions are tabulated. Included are the name(s), general location, elevation, relative site, successional status, principal tree and undergrowth associates, and the authority.

Growth of ponderosa pine was studied by the western Forest and Range Experiment Stations of the USDA Forest Service in response to increasing demands for better and more precise estimates of yields possible through intensive management. We summarized results of 15 to 20 years of growth after thinning each of five stands to a wide range of stocking levels. The stands-two in the Black Hills of South Dakota, and one each in northern Arizona, central Oregon, and northern California-ranged in size from small saplings to large poles and in age from about 20 to 90 years. Within the fundamental...

Maintaining permanent plot data with different sampling designs over long periods within an organization, as well as sharing such information between organizations, requires that common standards be used. A data structure for the description of the sampling design within a stand is proposed. It is based on the definition of subpopulations of trees sampled, the rules used to sample each subpopulation, and linking variables that tie these two elements together. In addition, the data structure includes the spatial relationship of plots within the stand as well as the precision with which tree...

To assess the adequacy of a permanent-plot data base for estimating growth and yield, one first needs to know how the plots in the data base are distributed in relation to the population they are presumed to represent. The distribution of permanent plots to study forest growth in the Inland Empire (northeastern Washington, northern Idaho, and western Montana) is displayed using a method that relates the permanent plots to the land base. The permanent plots are quantified into classes defined using inventory data that describe the land base. Five stand attributes are used to define the...

Maintaining permanent plot data with different sampling designs over long periods within an organization, and sharing such information between organizations, requires that common standards be used. A data structure for the description of the sampling design within a stand is proposed. It is composed of just those variables and their relationships needed to compile stand attributes and their variances. The data structure is able to incorporate changes in design that commonly occur through the life of a set of permanent plots. Using the data structure, seven actual or proposed designs, from...

Seventy-seven seedling populations of Douglas-fir (Pseudotsuga menziesii var. glauca) sampled from near the Continental Divide in Idaho and Montana exhibited pronounced genetic differences when compared in three common environments. Differentiation involved several traits that are components of an annual developmental cycle that must be completed within a growing season of finite length. Consequently, the elevational and geographic clines of genetic variation tend to parallel variation in the length of the growing season at the seed source. Such clines suggest that maladaptation in...