Treesearch

Due to their high ecological and economic value, oaks (Quercus spp.) are a desirable species group for mixedwood management. However, little information exists on oak competitiveness at the local, neighborhood scale in harvest gaps beyond the first few growing seasons. The objective of this research is to determine if oak competitive status is related to neighborhood composition and gap size. A total of 156 oak stems at least 3.5 inches in diameter at breast height and their respective neighborhoods were sampled in nine experimental harvest gaps (ranging in size from 0.25 to 1.0 acre) on...

The efficiency of shelterwood cutting in providing natural regeneration of bottomland oaks (Quercus spp.) is well documented. Typically, assuming environmental conditions are satisfactory, research projects yield adequate regeneration levels for targeted oak species. However, skepticism is often encountered when promoting the method for commercial operations in landowner management practices. Much of this hesitancy results from observing insufficient levels of oak regeneration after application of poor management technique. This study assesses viability of the system when established under...

Survival of individual stems selected as retention trees in irregular shelterwoods is important as these stems are expected to remain for 20 percent or longer of the subsequent rotation. In mountainous terrain where windstorms may occur regularly and prescribed fire may be utilized to improve regeneration composition, survival of retention trees becomes less certain. An upland, mixed hardwood stand in Morgan County, Tennessee, received an irregular shelterwood harvest and a burn or no-burn treatment between 2014 and 2016. Retention tree assessments were made 3.5 years post-harvest and 2.5...

Forests capture carbon dioxide through the process of photosynthesis. However, forests also respire carbon dioxide into the atmosphere. Soil respiration (Rs) is a significant source of atmospheric carbon dioxide. A portion of Rs comes from the process of microorganisms breaking down carbon sources in the soil while another portion is from respiring roots (Gough and others 2008). Even small changes in Rs can have a significant impact on whether a forest will behave as a carbon source or a carbon sink (Schlesinger and Andrews 2000). Therefore, considerable attention has recently been focused...

Investigating the suitability of hybrid sweetgum (Liquidambar formosana x styraciflua) as a biomass feedstock for Western Gulf forest industries requires information on stand yields. Using data from 2-year-old (1-0 seedling stock) hybrid sweetgum trees, equations were developed to estimate stem volume, comprising both wood and bark, on an afforested site in north Louisiana. Dummy variable statistical analyses concluded all data could be pooled across herbicide and varietal treatments to produce a single model system. Eighty-eight trees were measured for stem diameter at 1-foot increments...

Forests are subject to large-scale disturbance by harvesting and site preparation. An important question is whether soils can sustain the long-term needs of forest stands under intensive site preparation, shortened rotations, and higher utilization standards (Powers and others 1990). The effects of harvest intensity and site preparation on soil properties and stand productivity are being analyzed as part of the U.S. Department of Agriculture (USDA), Forest Service, Long-Term Soil Productivity (LTSP) studies.

Soil carbon dioxide (CO2) evolution is a combined product of the metabolic activity of plant roots and both free-living and symbiotic heterotrophs. Soil CO2 efflux (Sf) rates are the second largest carbon flux in the global carbon cycle and the largest terrestrial contributor of CO2 (Raich and Schlesinger 1992). The components of Sf can be broken down into heterotrophic respiration (RH) and autotropic root respiration (RR). Quantifying Sf and understanding the contribution of RH and RR on intensively managed sites is fundamental to understanding the carbon cycle and implications for carbon...

Severe wind events have devastating impacts on forests throughout the United States. Events such as tornadoes and hurricanes can destroy standing timber, produce stresses that impact wood quality, and leave debris that leads to susceptibility to additional impacts. Data for tornado and hurricane occurrences was obtained and the width of these storms calculated using Geographic Information Systems software. The storm tracks were then used to extract impacted forested pixels in Louisiana to determine the acreage impacted, by forest type, within the State. Approximately 238,000 forested acres...

The forest herbaceous layer provides important ecosystem services in the central United States. However, human impacts have caused declines of many of these species. Restoration of this layer is uncommon in temperate forests, so best practices are not yet established. There has been widespread concern about negative outcomes (for example, failure due to genetic swamping or outbreeding depression) when plant material is transferred beyond a local scale. Current practice is to use local sources under the assumption that they are optimal genotypes for the site. However, few local sources are...

Two species of silver fly, Leucopis argenticollis (Zetterstedt) and Leucopis piniperda (Malloch) (Diptera: Chamaemyiidae), from the Pacific Northwest region of North America have been identified as potential biological control agents of hemlock woolly adelgid (Hemiptera: Adelgidae: Adelges tsugae Annand) in eastern North America. The two predators are collectively synchronized with A. tsugae development. To determine whether adult emergence of the two species of silver fly are also synchronized with one another, we collected adult Leucopis which emerged from A. tsugae-infested western...