Treesearch

Wildland fire rate of spread (ROS) and intensity are determined by the mode and magnitude of energy transport from the flames to the unburned fuels. Measurements of radiant and convective heating and cooling from experimental fires are reported here. Sensors were located nominally 0.5mabove ground level. Flame heights varied from 0.3 to 1.8 m and flaming zone depth varied from 0.3 to 3.0 m. Fire ROS derived from observations of fire transit time between sensors was 0.10 to 0.48 m s
1. ROS derived from ocular estimates reached 0.51 m s
1 for heading fire and 0.25 m s
1 for backing fire....

The majority of humanity now lives in cities or towns, with this proportion expected to continue increasing for the foreseeable future. As novel ecosystems, urban areas offer an ideal opportunity to examine multi-scalar processes involved in community assembly as well as the role of human activities in modulating environmental drivers of biodiversity. Although ecologists have made great strides in recent decades at documenting ecological relationships in urban areas, much remains unknown, and we still need to identify the major ecological factors, aside from habitat loss, behind the...

An analysis of the urban forest in Philadelphia, Pennsylvania, reveals that this city has an estimated 2.9 million trees (encompassing all woody plants greater than 1 inch diameter at breast height [d.b.h]) with tree canopy that covers 20 percent of the city. The most common tree species are spicebush, black cherry, ash, tree-of-heaven, and boxelder, but the most dominant species in terms of leaf area are sycamore spp. (including London planetree), northern red oak, black walnut, red maple, and Norway maple. Trees in Philadelphia currently store about 702,000 tons of carbon (2.6 million...

The benefits derived from urban forest ecosystems are garnering increasing attention in ecological research and municipal planning. However, because of their location in heterogeneous and highly-altered urban landscapes, urban forests are vulnerable and commonly suffer disproportionate and varying levels of stress and disturbance. The objective of this study is to assess and analyze the spatial and temporal changes, and potential vulnerability, of the urban forest resource in Toronto, Canada. This research was conducted using a spatiallyexplicit, indicator-based assessment of vulnerability...

There is a long history of controversy surrounding Forest Service decisions; the agency is sued for NEPA violations more often than any other federal agency. Consequently, the Forest Service has spent a significant amount of time and resources addressing the requirements of the NEPA process, trying to identify and reduce risk factors associated with administrative and judicial challenges to NEPA decisions.This synthesis and annotated bibliography seeks to develop a more comprehensive understanding of the factors that influence NEPA challenge risks and successes in order to inform and guide...

Ecosystem services are the benefits that nature provides through natural processes. For example, plants provide clean air, natural fire helps cycle nutrients, and bats act as insect control. Ecosystem services are valued by people, even if people do not always think about where these services. Scientists have studied ecosystems for a long time. The concept of ecosystem services, however, is relatively new. The identification of ecosystem services enables scientists to show people that ecosystems are important to everyone. Learn more about ecosystem services in this edition and then look...

The immune mechanisms that recognize inhaled Aspergillus fumigatusconidia to promote their elimination from the lungs are incompletely understood. FleA is a lectin expressed by Aspergillus fumigatusthat has twelve binding sites for fucosylated structures that are abundant in the glycan coats of multiple plant and animal proteins. The role of FleA is unknown: it could bind fucose in decomposed plant matter to allow Aspergillus fumigatusto thrive in soil, or it may be a virulence factor that binds fucose in lung glycoproteins to cause Aspergillus fumigatuspneumonia. Our studies show that...