Treesearch

Four new species of Dolichopodidae are described from central Pennsylvania: Campsicnemus wilderae Runyon, Dolichopus dracula Runyon, Dolichopus hurleyi Runyon, and Dolichopus frosti Runyon. Keys to males of Campsicnemus Haliday and Dolichopus Latreille with lamellate aristae are provided for species from eastern North America.

Fire exclusion, especially in the dry forests (i.e. those dominated or potentially dominated by ponderosa pine) has most often altered tree and shrub composition and structure and, though often overlooked in many locales, the forest floor from conditions that occurred historically (pre-1900).

Turbulence in the planetary boundary layer (PBL) well above the surface has been shown to be independent of the details of the surface roughness. In this region well-quantified similarity relationships work well when characterizing turbulent fluxes (e.g., Raupach, 1979). However, in the near-surface layer which is directly influenced by roughness elements, i.e., the roughness sublayer, turbulence exhibits dramatically varying properties depending on the detailed structure of the roughness elements (Shaw et al., 1974; Raupach, 1981; Raupach et al., 1996). Turbulence in the roughness...

Fast-response pressure fluctuations were included in the Canopy Horizontal Array of Turbulence Study (CHATS) at several heights within and just above the canopy in a walnut orchard. Two independent systems were intercompared and then separated. We present an evaluation of turbulence statistics - including the pressure transport term in the turbulence kinetic energy budget equation - within this canopy.

The mountain pine beetle, Dendroctonus ponderosae Hopkins, is considered one of the most economically important insect species in coniferous forests of western North America. Adult beetles are capable of successfully reproducing in at least 12 North American species of Pinus (Pineacea) from southern British Columbia to northern Baja Mexico. Mountain pine beetle adults attack live trees, and typically must kill the host for successful reproduction. Population outbreaks are most common in a few selected host species, such as lodgepole pine (P. contorta), ponderosa pine (P. ponderosa),...

The genus Dendroctonus (Coleoptera: Curculionidae, Scolytinae), originally described by Erichson in 1836, currently includes 19 species that are widely distributed. Seventeen species occur between Arctic North America and northwestern Nicaragua, and an additional two species are in northern Europe and Asia. Dendroctonus species attack and infest conifer hosts (Pinaceae) in the genera Larix, Picea, Pinus, and Pseudotsuga. Species within the genus can be identified by the host species they attack, egg gallery patterns, population behavior, and morphological distinctions. The smallest species...

Single wide-angle and stereo photographs display a range of forest ecosystems conditions and fuel loadings in montane subtropical forests of the Sierra Madre del Sur and temperate forests and montane shrubland of the northern Sierra Madre Oriental of Mexico. Each group of photographs includes inventory information summarizing overstory vegetation composition and structure, and biomass of understory, woody material, and litter and duff. This photo series is designed to help users to appraise fuel and vegetation conditions for fire management in forests of Mexico.

Effective implementation of the "multiple path" approach to managing green landscapes depends fundamentally on rigorous quantification of the composition and structure of the landscapes of concern at present, modelling landscape structure trajectories under alternative management paths, and monitoring landscape structure into the future to confirm whether management is having the expected effects on landscape structure. Indeed, quantification of current conditions, anticipation of future changes and monitoring these changes as they occur are the three foundational elements of adaptive...

Mountain pine beetle populations have reached outbreak levels in lodgepole pine forests throughout North America. The geographic focus of this report centers on the southern Rocky Mountains of Colorado and southern Wyoming. The epidemic extends much more widely, however, from the southern Rocky Mountains in Colorado in the United States to the northern Rocky Mountains in British Columbia and Alberta, Canada.

Landscape genetics, an emerging field integrating landscape ecology and population genetics, has great potential to influence our understanding of habitat connectivity and distribution of organisms. Whereas typical population genetics studies summarize gene flow as pairwise measures between sampling localities, landscape characteristics that influence population genetic connectivity are often continuously distributed in space. Thus, there are currently gaps in both the ability to analyze genotypic data in a continuous spatial context and our knowledge of expected of landscape genetic...