Treesearch

This study was undertaken to investigate the nutritive value of some of the more important forage species grazed by livestock in various areas of Colorado. The samples were analyzed for energy, protein, cellulose, vitamin A, calcium, phosphorus and magnesium. The digestibility coefficients of the plants, protein, energy and cellulose were also determined by the in vivo nylon bag technique. All species studied were deficient in at least one of the elements analyzed at some phenological stages. The nutrient deficient at more growth stages than any other element was phosphorus. The next most...

Green standing herbage of seeded big bluegrass (Poa ampla) and corresponding dry weight were each regressed as dependent variables (Y) on color infrared photo image density (X) obtained from two photoscales: 1:563 and 1:3855. Standing crop biomass expressed by the linear equation: Y = a + b(X) was from the 1:563 photoscale. The coefficient of determination r2 = 0.752) between image density and harvested dry weight was highly significant (P = 0.01). The same regression using the smaller photoscale (1:3855), although significant (P = 0.05), was not as good (r2 = 0.639). Mean image density of...

Optimum channel selection among 12 channels of multispectral scanner imagery identified six as providing the best information about 11 vegetation classes and two nonvegetation classes at the Manitou Experimental Forest (NASA Test Site 242). Intensive pre-processing of the scanner signals was required to eliminate a serious scan angle effect. Final processing of the normalized data provided acceptable recognition results of generalized plant community types. Serious errors occurred with attempts to classify specific community types within upland grassland areas. The consideration of the...

Optimum channel selection among 12 channels of multispectral scanner imagery identified six as providing the best information for computerized classification of 11 plant communities and. two nonvegetation classes. Intensive preprocessing of the spectral data was required to eliminate bidirectional reflectance effects of the spectral imagery caused by scanner view angle and varying geometry of the plant canopy. Generalized plant community types -- forest, grassland, and hydrophytic systems--were acceptably classified based on ecological analysis. Serious, but soluble, errors. occurred with...

Why Is a Shrub Symposium Needed? The answer to this question is obvious in view of the great volume of research that has been done with grasses and forbs while, in contrast, there has been considerably less research and development of shrubs. Yet, shrubs offer tremendous potentials for man's benefit in making the arid and semi - arid lands of the world more productive and useful. In light of the great range of adaptation possessed by shrubs as a group, it is quite amazing that they have escaped intensive study to the same degree as other plant groups. Shrubs range from some of the highest...

Numerical and analytical solutions of the Fickian diffusion equation were used to determine the effects of precipitation on dead cylindrical forest fuels. The analytical solution provided a physical framework. The numerical solutions were then used to refine the analytical solution through a similarity argument. The theoretical solutions predicted realistic rates of water exchange and the internal distribution of the water. The theory also (1) predicted that precipitation duration rather than amount or rate determined the amount of water uptake and (2) provided a function useful in...

In the northern Rocky Mountains, in Idaho, data collected during three winters demonstrate why there is always less snow beneath the canopy of a cedar-hemlock forest than in the adjacent small openings. The author presents as evidence the differential release of water, which originates in the canopy as throughfall-drip, thus accounting for part of the deficiency in snow water equivalent beneath the canopy by April 1. Such informative data were made possible by a new instrument designed to collect waterflow from the snowpack.

Stands of aspen on the Gros Ventre elk winter range of northwestern Wyoming are suffering high mortality and are not regenerating satisfactorily. If the 1970 mortality rate (3.6 percent) continues, about a two-thirds reduction in the numbers of tree-sized aspen can be expected by year 2000. Collected evidence suggests that the mortality rate is unusually high because of a combination of pathogenic fungi, injurious insects, and physiological stress that follow bark wounding of tree trunks. Elk and possibly moose are suspected of causing most of these severe trunk injuries. Sooty bark...

Around the world today is a steadily growing pressure on forest resources--pressure to produce the many goods and services that such lands provide. Highly developed countries and those striving for greater social and economic gains, both look to forests for the material wealth and environment to satisfy human needs. But as efforts increase to manipulate natural forests to better serve mankind, we find that many new problems arise and old ones intensify. Forestry scientists have responded by bringing their skills to focus more effectively on a large array of critical problems. Forest...

A mathematical fire model for predicting rate of spread and intensity that is applicable to a wide range of wildland fuels and environment is presented. Methods of incorporating mixtures of fuel sizes are introduced by weighting input parameters by surface area. The input parameters do not require a prior knowledge of the burning characteristics of the fuel.