Treesearch

Forest road aggregate changes due to traffic. The physical processes that cause these aggregate changes need to be understood for more effective road management that can help reduce maintenance costs and efforts, and negative environmental impacts of forest roads. This study modeled three processes that could change the particle size distribution (PSD) of forest road aggregate: crushing (breaking down the surfacing material), subgrade mixing (moving upward of fine-grained, roadbed sediment), and sweeping (migration of loose aggregate particles to the shoulder and roadside by tire action)....

The forests of the southern Rocky Mountains of North America have experienced substantial change since European colonization. High-grade logging, forest grazing practices, and fire suppression have altered once park-like ponderosa pine-dominated ecosystems into dense forests in need of restoration treatments, but such treatments are challenged by the low-value wood products removed during treatment. This study aims to understand and evaluate restoration harvest practices in the southern Rocky Mountains in terms of equipment used, production rates, and costs under both observed and modeled...

Current methods for determining plant age of shrub species require destructive sampling and annual growth ring analysis on the primary stem. Although individual plant ages can frequently be determined in this manner, the method is time consuming and of limited value for plants that have lost stem wood from stem splitting and rot. Nondestructive methods for estimating big sagebrush (Artemisia tridentata Nutt.) plant age would be useful in assessing stand age structure and population dynamics at variable spatial scales. The purpose of this study was to test a suite of traits for potential...

Physiological responses to temperature extremes are considered strong drivers of species’ demographic responses to climate variability. Plants are typically classified as either avoiders or tolerators in their freezing‐resistance mechanism, but a gradient of physiological‐threshold freezing responses may exist among individuals of a species. Moreover, adaptive significance of physiological freezing responses is poorly characterized, particularly under warming conditions that relax selection on cold hardiness.

Many North American birds associated with forest disturbances such as wildfire and mountain pine beetle (Dendroctonus ponderosae) outbreaks are declining in abundance. More information on relationships between avian abundance and forest structure and disturbance is needed to guide conservation and management. Our objective was to determine densities of American Three-toed Woodpecker (Picoides dorsalis), Black-backed Woodpecker (Picoides arcticus), Red-breasted Nuthatch (Sitta canadensis), Brown Creeper (Certhia americana), and White-winged Junco (Junco hyemalis aikeni) in relation to...

Invasive populations of Dalmation toadflax [Linaria dalmatica (L.) Mill.] and yellow toadflax (Linaria vulgaris Mill.) are widespread throughout the Intermountain West, where gene flow between these nonnative species is producing vigorous and fertile hybrids. These hybrid toadflax populations are less responsive to herbicides than either parent species, and biocontrol agents routinely released on L. dalmatica and L. vulgaris often fail to establish on hybrid hosts. Early detection of hybrid Linaria populations is therefore essential for effective management, but resources are limited for...

Land managers require information about the ongoing and potential effects of future climate to coordinate responses for ecosystems, species, and human communities at scales that are operationally meaningful. Our study focused on the vulnerability for all upland ecosystem types of Arizona and New Mexico in the southwestern United States. Local vulnerability across the two-state area was represented by the level of departure for late 21st-century climate from the characteristic pre-1990 climate envelope of the ecosystem type at each given location, resulting in a probability surface of...

During the last seventy years, numerous models have been developed to predict soil erosion; some models also predict concomitant sediment deposition. All have been proven inadequate and/or inaccurate in one respect or another. This paper discusses the application of the new-generation Unit Stream Power Erosion and Deposition (USPED) model at the US Army’s Yakima Training Center (YTC), Washington. We incorporated a novel approach that compares model results with observed soil erosion and sediment deposition across the landscape in a spatially distributed fashion. The model results matched...

Unitl recent decades, discussions involving the chestnut concentrated on resistance breeding results. Little discussion took place on the effects that chestnut restoration would have on ecosystem processes and functions, including wildlife population dynamics. The initial motivation for breeding program was largely to recover an important economic resource. It was not until the 1990s and early 2000s that the conversation shifted to include potential impacts on the ecosystem.

Reforestation of upland oak species on productive forest sites in the Southern Appalachian region will require different prescriptions than in other regions where yellow-poplar (Liriodendron tulipifera L.) is not a primary competitor. We present results from three studies on highly productive sites [site index, base age 50, for northern red oak (Quercus rubra) ranged from 78 to 98 feet] that represented a broad range of residual basal areas and competition control methods. In all studies, we used seedlings produced using the most advanced bare-root nursery protocols currently available...