Treesearch

Advanced decay caused by Phellinus tremulae was estimated in 295 trembling aspen on 30 plots in 2 Minnesota counties using existing inventory guides, and then measured by felling and sectioning the trees. In standing trees, decay volume was underestimated by 38% compared to measured decay volume in felled trees. The most reliable external indicator of decay was the presence of conks of the fungus. Results indicate that decay associated with conks in the first 16ft of the trees accounted for nearly 70% of the total volume loss. Decay volume in trees with no conks averaged less than 2%...

A recent paper in this journal (Solecki and Welch, 1995) describes how urban parks that lie between racially different neighborhoods can become "green walls" or barriers to use and appreciation. Although this phenomenon is well grounded in the experience of many who plan for, manage, and live near parks in racially and ethnically segregated cities, an analysis of the authors' logic and methods suggests that there may be better ways to test the green wall thesis than with physical-biological measures of park tree condition. Examples from research in Chicago area parks illustrates how...

From pre-trip planning through post-trip remembering, vacations unfold over long periods of time. Through the course of a trip the same travel information may be used repeatedly but with different levels of success and satisfaction. These experiential fluctuations over time were examined in a study of trip planners, who collected information from a chamber of commerce before leaving home, to understand how information was applied in situ during their vacation. Travelers with various lengths of stay were segmented into unique groups and their information use was modeled by prior experience...

Large floods are an important process controlling the structure and function of stream ecosystems. One of the ways floods affect streams is through the recruitment of coarse woody debris from stream-side forests. Stream valley geomorphology may mediate this interaction by altering flood velocity, depth, and duration. Little research has examined how floods and geomorphic features interact to control debris recruitment from riparian forests. With this in mind, we examined debris recruitment resulting from tree mortality during a record flood in a Georgia (U.S.A.) stream. We quantified...

Spatially explicit models that combine remote sensing with geographic information systems (GIS) offer great promise to land managers because they consider the arrangement of landscape elements in time and space. Their visual and geographic nature facilitate the comparison of alternative landscape designs. Among various activities associated with forest management, none cause greater concern than the impacts of timber harvesting on the composition, structure, and function of landscape ecosystems. A timber harvest allocation model (HARVEST) was used to simulate different intensities of...

We tested the hypothesis that green leaf volatiles (GLVs) disrupt the response of spruce beetles, Dendroctonus rufipennis Kirby, and western pine beetles, Dendroctonus brevicomis LeConte, to attraetant-baited traps. Two green leaf aldehydes, hexanal and (E)-2-hexenal, reduced the number of spruce beetles captured to intermediate levels and one green leaf alcohol, hexanol, significantly reduced spruce beetle trap catches. Together, the green leaf alcohols and aldehydes reduced trap catches by 78.7 and 89.3% for males and females, respectively. The green leaf aldehyde, (E)-2-hexenal, and two...

We tested the feasibility of competitive exclusion as a potential management tactic for the spruce beetle, Dendroctonus rufipennis Kirby, using pre-attack baiting with pheromones of 2 secondary species, Ips tridens Mannerheim and Dryocoetes affaber Mannerheim. Spruce beetle attack densities, gallery lengths per square meter, and progeny densities were significantly reduced by up to 78% in individual felled trees baited with the I. tridens pheromones (+/-)-ipsdienol and (-)-cis-verbernol, and the D. affaber pheromones (+/-)-exo-and (+)-endo-brevicomin, or pheromones of both secondary...

To integrate multiple uses (mature forest and commodity production) better on forested lands, timber management strategies that cluster harvests have been proposed. One such approach clusters harvest activity in space and time, and rotates timber production zones across the landscape with a long temporal period (dynamic zoning). Dynamic zoning has been shown to increase timber production and reduce forest fragmentation by segregating uses in time without reducing the spatial extent of timber production. It is reasonable to wonder what the effect of periodic interruptions in the implementati...

In 1992, a federal quarantine was imposed by the United States Department of Agriculture (USDA)Animal and Plant Health Inspection Service (APHIS) on the movement of pine from infested counties to uninfested counties within the US (Haack 1997; Haack et al. 1997). The Tomicus quarantine allows for the movement of pine logs, pine Christmas trees, and pine nursery stock during specific times of the year based on the beetle's biology. For timing specific requirements of the quarantine, APHIS often uses single dates for the entire infested area. APHIS recognizes that considerable climatic...

Gray wolves (Canis lupus) in parts of the United States and Europe live in networks of disjunct populations, many of which are close to human settlement. Because wolf management goals include sustaining disjunct populations, it is important to ask what types of areas and protections are needed for population survival. To predict the effects of different levels of human-caused mortality, we created a simulation model for a disjunct wolf population living in a semi-wild landscape with abundant, well distributed prey. The landscape included a maximum of 16 territories divided into core and...