Treesearch

Seasonal food selection and digestibility by tame white-tailed deer (Odocoileus virginianus) were studied in the white pine (Pinus strobus)–Canada hemlock (Tsuga canadensis) and lowland conifer types, areas representative of important deer habitat in the northeastern United States. Deer selected highly digestible late spring, summer, and autumn diets. Winter and early spring food were less digestible. Forbs and newly grown leaves of hardwood plants were the most commonly selected late spring and summer foods; mushrooms and hardwood leaves were selected during autumn. Winter foods consisted...

Patterns of colonization by pioneering species and their allelochemic and competitive relations were studied in 4 reclaimed areas in western North Dakota, ranging in age from 1 to 4 years after mining; a site from a native mixed grass prairie was used for comparison. Early changes in floristic composition revealed that despite seeding of agronomic species, initial colonization was by fugitive species. Of the 95 species recorded, Kochia scoparia (Chenopodiaceae) dominated in the first 2 years after mining. Kochia had relatively low densities in the first year (50-80 plants m-2), but was...

Observational evidence from nine crown fires suggests that horizontal roll vortices are a major mechanism in crown-fire spread. Post-burn aerial photography indicates that unburned tree-crown streets are common with crown fire. Investigation of the understory of these crown streets after two fires showed uncharred tree trunks along a center line. This evidence supports a hypothesis of vortex action causing strong downward motion of air along the streets. Additionally, photographs of two ongoing crown fires show apparent horizontal roll vortices. Discussion also includes laboratory and...

Five new species of Urosigalphus are described. One, diversus, is the first species of the subgenus Microurosigalphus to be collected in South America. One, alius, belongs to the subgenus Urosigalphus and three, flexus, porteri, and surinamensis, belong to the subgenus Neourosigalphus. Changes in existing keys to South American species are presented.

Two new species of Urosigalphus subgenus Neourosigalphus Gibson are described, yucatanensis and meridianus. A key to Mexican and Central American species is presented.

Precommercial thinnings were repeated four times in a central hardwood sapling stand beginning at age 8 and ending at age 22. Treated plots were thinned on an area-wide basis to specified density levels of 30-, 50-, and 70-percent stocking. The species composition of all stems in the stand was altered somewhat by thinning, but similar trends occurred on control plots. The species composition, growth, and quality of potential crop trees were not improved substantially by thinning. Results indicate that repeated areawide precommercial thinnings to specified density levels is not an effective...

The National Urban and Community Forestry Leaders Council and the American Forestry Association believed it was time to reconvene the nation's urban foresters. It had been four years since the first National Urban Forestry Conference was held in Washington, DC. The ideas, excitement, and energy of those that attended this second conference were a convincing demonstration of the grass-roots desire for the conference. The willingness of the sponsors demonstrates the depth of the urban and community forestry movement. The proceedings of the Conference have been compiled in this volume in...

The American chestnut was an important tree in the history of the United States. The fruit of chestnut was not only important to man and his domesticated animals but to the wildlife of the eastern forests. The tree comprised over 25 percent of the eastern hardwood forest and its natural range included at least 200 million acres. On good sites, the tree often grew 1 inch in diameter each year, faster than any of its associated hardwoods. Its ability to grow on poorer sites and produce a straight, clear bole made it an even more valuable species. Chestnut timber was of superior quality and...

Six plots of pine trees harboring high densities of N. sertifer larvae were sprayed with the nucleopolyhedrosis virus (NPV) of this species. Half of these plots were resprayed in the second year of the study. Polyhedral inclusion bodies (PIB) were recovered in all plots from soil and foliage sampled at fixed time intervals within a 21-month period from the initial date of spraying. The concentration of PIB from both soil and foliage samples in the second year were generally lower in plots treated once than in those treated twice. NPV-induced larval mortality in plots sprayed once was 100%...

Linear regression analysis of probit mortality versus several concentrations of nucleopolyhedrosis virus of Neodiprion sertifer resulted in the equation Y = 2.170 + 0.872X. An LC50 was calculated at 1758 PIB/ml. Also, the incubation time of the virus was dependent on its concentration. Most insect viruses possess the potential of causing 100% mortality when employed against some pest species populations (Bailey 1973). However, Franz (1964) pointed out that such a result is not always desirable. For instance, if the virus proves persistent and capable of being transmitted by the target...