Treesearch

In a tick-spirochete survey conducted from fall 1989 through fall 1992 in northwestern Wisconsin, 4,256 birds (composed of 91 species) were examined for ticks. Infestations were recorded for 400 birds (composed of 30 species). Of 1,184 ticks taken from 335 birds (composed of 26 species), 60 (5%) Haemaphysalis leporispalustris (Packard) from eight species of birds were infected with the Lyme disease spirochete, Borrelia burgdorferi (Johnson, Schmid, Hyde, Steigerwalt and Brenner). Similar surveys conducted in 1990 and 1991 in Minnesota and Michigan yielded 223 H. leporispalustris from 61...

Determination of the carbon balance in a broad forest region like the Alaskan boreal forest requires the development of a number of important environmental (state factors) classes to allow for the development of carbon balance estimates.

Models of canopy gas exchange are needed to connect leaf-level measurement to higher scales. Because of the correspondence between leaf gas exchange and water use, it may be possible to predict variation in leaf gas exchange at the canopy level by monitoring rates of branch water use.

The biogeochemistry of C, N, and S was studied for six years at the Howland Integrated Forest Study (HIFS) site by measuring those constituents in major above- and below-ground pools and fluxes. Leaching losses of C from the solum were much less than CO2 efflux, with a mean annual leaching rate of 31.2 kg ha-1 yr-1. Carbon return to the forest floor via litterfall and outputs via CO2 efflux were relatively equal. Mean annual total (wet+plus) atmospheric deposition inputs were 5.51 kg ha-1 yr-1 for NO3--N, 2.64 kg ha-1 yr-1 for NH4+-N, and 8.09 kg ha-1 yr-1 for SO42--S; wet deposition...

During the past three years, we have examined the effects of ozone (O3) and carbon dioxide CO2, alone and in combination, on the growth and physiology of trembling aspen (Populus tremuloides Michx.).

Comparisons are made of the effects of temperature and duration of low temperature on egg hatch of North American and Russian gypsy moth, Lymantria dispar), under controlled laboratory conditions. Percentage of hatch of embryonated eggs, days to 1st hatch after incubation at warm temperature and temperal distribution of hatch are used to compare hatch of different strains under various conditions. Eggs from 2 Russian gypsy moth strains required less exposure to low temperature to be able to hatch than did eggs from a North American strain. Hatch took longer to begin and proceeded more...

In recent years the hardwood lumber industry has become increasingly concerned about the availability and quality of hardwood sawtimber. However, these concerns seem to contradict USDA Forest Service estimates of increased volume and quality of hardwood sawtimber. This paper examines changes in eastern hardwood sawtimber inventories and the apparent contradiction between the industry's perception of decreasing sawtimber availability and the Forest Service's contention of increasing timber inventories. This study did not find a single explanation for the apparent contradiction. Many of the...

Mills should have the option to crosscut red oak lumber prior to gang-ripping to remove crook and worthless material and to take advantage of the quality differences between board ends. At least half of No: 1 and 2A Common red oak boards will have end-to-end yield differences of at least 10 percent. Preprocessing will cause a slight decrease in overall yield but will allow greater control of the material fed to the gang ripsaw. It also appears that fewer short lengths will be generated from the better sections of the boards.

A round table discussion was convened to explore divergent views on the potential for natural forest management (NFM) for timber to contribute to wide-scale maintenance of forest cover and biological diversity in tropical forests. The general argument for NFM for timber is that, by conferring relatively more economic value on forests that alternative forest uses, NFM for timber is a necessary, though imperfect, means by which extensive areas of forest cover and a large measure of their biological diversity would be maintained outside nature reserves. The discussion centered on five topics:...

This study examined the effect of clustering timber harvest zones and of changing the land use categories of zones (dynamic zoning) over varying temporal and spatial scales. Focusing on the Hoosier National Forest (HNF) in Indiana, USA as a study area, I used a timber harvest allocation model to simulate four management alternatives. In the static zoning alternative, harvests were dispersed throughout the timber harvest land base (65% of HNF) for 15 decades. The three dynamic zoning alternatives varied in the degree to which harvests were clustered in time and space. Two levels of harvest...