Treesearch

Sagebrush steppe ecosystems in the United States currently (2015) occur on only about one-half of their historical land area because of changes in land use, urban growth, and degradation of land, including invasions of non-native plants. The existence of many animal species depends on the existence of sagebrush steppe habitat. The greater sage-grouse (Centrocercus urophasianus) is a landscape-dependent bird that requires intact habitat and combinations of sagebrush and perennial grasses to exist. In addition, other sagebrush-obligate animals also have similar requirements and restoration...

Shore pine, which is a subspecies of lodgepole pine, was a widespread and dominant tree species in Southeast Alaska during the early Holocene. At present, the distribution of shore pine in Alaska is restricted to coastal bogs and fens, likely by competition with Sitka spruce and Western hemlock. Monitoring of permanent plots as part of the United States Forest Service Forest Inventory and Analysis program identified a recent loss of shore pine biomass in Southeast Alaska. The apparent loss of shore pine is concerning, because its presence adds a vertical dimension to coastal wetlands,...

Assessment of forest carbon storage dynamics requires a variety of techniques including simulation models. We developed a hybrid model to assess the effects of silvicultural management systems on carbon (C) budgets in longleaf pine (Pinus palustris Mill.) plantations in the southeastern U.S. To simulate in situ C pools, the model integrates a growth and yield model with species-specific allometric and biometric equations and explicitly accounts for the impacts of both thinning and prescribed fire. To estimate the ex situ C pool, the model used the outputs of merchantable products from the...

In songbirds, female mate choice may be influenced by how well a male performs his songs. Performing songs well may be especially difficult if it requires maximizingmultiple aspects of performance simultaneously.We therefore hypothesized that, in a population of prairie warblers, the males most attractive to females would be those with superior performance in more than one facet of singing.We tested this prediction by comparing different aspects of song performance, as well as different combinations of these aspects, to determine which were the best predictors of first-egg date, which we...

We present our recent observations and compile other accounts of sightings or captures of 30 additional bird species reported for San Salvador Island, The Bahamas, since Sordahl compiled his checklist in 1996. Most are Nearctic-Neotropical migratory birds that either spend the non-breeding season on the island or stop over during migration. Additionally, based on our own and others' observations, we revised the status of 19 bird species that were previously listed as "transient, vagrant, or uncertain" on the island, and 9 species listed as "rare". We captured or observed many of these...

The gypsy moth from Asia (two subspecies) is considered a greater threat to North America than European gypsy moth, because of a broader host range and females being capable of flight. Variation within and among gypsy moths from China (nine locations), one of the native countries of Asian gypsy moth, were compared using DNA barcode sequences (658 bp of mtDNA cytochrome c oxidase subunit 1 [COI] sequence), together with two restriction site mtDNA markers (NlaIII and BamHI in COI), which is the standard system used to distinguish European gypsy moths from Asian gypsy moths. Relatedness of...

Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae), an invasive phloem-feeding insect native to Asia, threatens at least 16 North American ash (Fraxinus) species and has killed hundreds of millions of ash trees in landscapes and forests. We conducted laboratory bioassays to assess the relative efficacy of systemic insecticides to control emerald ash borer larvae in winter 2009 and 2010. Second- and third-instar larvae were reared on artificial diet treated with varying doses of emamectin benzoate (TREE-age, Arborjet, Inc., Woburn, MA), imidacloprid (Imicide, J. J...

Fire is a prevalent feature of many landscapes and has numerous and complex effects on geological, hydrological, ecological, and economic systems. In some regions, the frequency and intensity of wildfire have increased in recent years and are projected to escalate with predicted climatic and landuse changes. In addition, prescribed burns continue to be used in many parts of the world to clear vegetation for development projects, encourage desired vegetation, and reduce fuel loads. Given the prevalence of fire on the landscape, authors of papers in this special series examine the complexitie...

Mountain pine beetle (Dendroctonus ponderosae) is an important disturbance agent in Pinus ecosystems of western North America, historically causing significant tree mortality. Most recorded outbreaks have occurred in mid elevation lodgepole pine (Pinus contorta). In warm years, tree mortality also occurs at higher elevations in mixed species stands.

Mountain pine beetle, Dendroctonus ponderosae Hopkins, is the most significant mortality agent in pine forests of western North America. Silvicultural treatments that reduce the number of susceptible host trees, alter age and size class distributions, and diversify species composition are considered viable, long-term options for reducing stand susceptibility to mountain pine beetle-caused tree mortality. Short-term efficacy of thinning treatments has been evaluated, but long-term efficacy has not. We evaluated mountain pine beetle-caused lodgepole pine mortality in 2008, ~28 years after...