Treesearch

In the last decade, pine forests throughout much of the western United States have been ravaged by the mountain pine beetle (Dendroctonus ponderosae). This bark beetle is native to the United States and has been responsible for massive tree kills in the past. The current outbreak, however, has been notably severe and wide ranging and the effects have been more dramatic and longer lasting. Scientists have documented infestations in areas never before recorded. The insect has expanded its host selection from its more-preferred species of pine— ponderosa, lodgepole, limber, whitebark, and...

An Agrobacterium tumefaciens-mediated genetic transformation system was successfully developed for white ash (Fraxinus americana) using hypocotyls as the initial explants. Hypocotyls isolated from mature embryos germinated on Murashige and Skoog (MS) medium supplemented with 22.2 µM 6-benzyladenine (BA) and 0.5 µM thidiazuron (TDZ) were transformed using A. tumefaciens strain EHA105 harboring the binary vector pq35GR containing a fusion gene between neomycin phosphotransferase (nptII) and gusA, as well as an enhanced green fluorescent protein (EGFP).

Stump sprouts contribute to the regeneration potential of upland hardwood forests in the southern Appalachian Mountains (Cook and others 1988); however, most of the information regarding stump sprout potential and subsequent sprout growth and development is from studies following regeneration cuts.

While dominant throughout much of the eastern United States, a recent decline in oak regeneration has merited substantial research. Ultimately, successful regeneration entails the establishment of advance reproduction of sufficient size and density to provide a high probability of ascendancy to dominant or co-dominant status. Potential prescriptions for achieving this include manipulation of light infiltration and control of competing vegetation through shelterwood harvests and prescribed burning. Diameter-limit cutting is a method used on private forests which creates diverse post-harvest...

Challenges remain to regenerating oak (Quercus spp.) in eastern upland hardwood forests. It is well established that to be competitive, advance oak reproduction must be of sufficient size to respond favorably upon release. We also know altering the understory light regime, through reductions in stand stocking, basal area, or canopy cover, promotes the growth and competitiveness of small oak advance reproduction. Reductions in stand density can be accomplished by herbicide treatment of the existing midstory, prescribed fire, or harvesting. We found midstory herbicide treatment resulted in...

Mechanical site preparation is frequently proposed to alleviate problematic soil conditions when afforesting retired agricultural fields. Without management of soil problems, any seedlings planted in these areas may exhibit poor growth and survival. Seeding height and groundline diameter are often used to evaluate effects of site preparation methods, but stem biomass may provide a more appropriate assessment of treatment effect in some circumstances. Four mechanical site preparation and two post-plant Oust XP® treatments were utilized in an attempt to evaluate resulting stem biomass...

Emerging plant economics spectrum theories were confirmed across temperate forest systems of the eastern US where the use of a forest stand's mean wood density elucidated forest volume and biomass production dynamics integrating aspects of climate, tree mortality/growth, and rates of site occupancy.

Aim The American pika (Ochotona princeps) appears to have experienced climate mediated upslope range contraction in the Great Basin of North America, but this result has not yet been extended to other portions of the pika’s range. Our goals were: first, to determine the environmental parameters that most influence current pika distribution within California; second, to infer whether these constraints explain extirpations that have occurred in California; third, to predict future extirpations; and fourth, to advance methods for assessing the degree to which pikas and other climate-sensitive...

Thousands of acres are planted every year with genetically improved seedlings; but while pine continues to be extensively explored, the same is not true for hardwoods due to costs and rotation length. An improved cherrybark oak (Quercus pagodaRaf.) seed orchard exists in North Little Rock, AR, providing an opportunity to evaluate hardwood improvement. However, the cost and limited testing of these seedlings have been large limiting factors in their deployment. In February 2012, improved and woods-run seedlings were hand-planted at two sites in southern Arkansas including a site near Hope,...

Recent studies suggest a troubling decline in the abundance of red oak species (Quercus spp., Section Erythrobalanus) in bottomland forests of the southeastern United States. We assessed red oak advance regeneration and associated tree species in relation to light availability in a 77-year-old oak-dominated stand 5 years after late rotation thinning. Residual basal areas across four thinning treatments ranged between 48 and 69 square feet per acre and were compared to an unthinned control (108 square feet per acre). Available understory light was significantly greater in the most intensive...