Treesearch

Research on several hundred well-manufactured 1 and 2A Common red oak boards shows that better edging and/or trimming or division-based remanufacturing can produce boards of higher grade and value. Division-based remanufacturing divides a board into as many as four smaller boards. The UGRS computer program (3,4) grades digitized boards, examines their remanufacturing potential, remanufactures to the highest valued solutions greater than the original board values, and displays the size, defect location, and grade of new boards for UGRS analysis. An example analysis of the effects of such...

Forest inventory statistics developed by the USDA Forest Service are used by customers ranging from forest industry to state and local economic development groups. In recent years, these statistics have been used increasingly to justify greater utilization of the eastem hardwood resource or to evaluate the sustainability of expanding demand for hardwood roundwood and sawtimber. This paper examines Forest Inventory and Analysis (FIA) statistics and demonstrates how they can be misinterpreted. In some cases, the total fiber supply can be underestimated because cull trees are not included in...

A variety of silvicultural techniques have been suggested for managing forest defoliating insects. The objectives focus on minimizing defoliation or minimizing damage from defoliation. The theoretical foundations of many approaches have been built upon observation and correlation, and very little reliable empirical evidence exists to support the objectives of silvicultural manipulations. Existing experimental data have yielded inconsistent results. We review the conceptual framework and underlying assumptions of the major silvicultural approaches recommended or in use in North America....

Since the mid-1980s, the volume of sawtimber sold by eastern national forests has declined by 55 percent. Factors contributing to this decline include increased recreational demands, political pressures from environmentalists and the adoption of ecosystem management techniques. This paper examines the changes in the sales of roundwood products from 1985 to 1997 for three eastern regions that contain relatively large quantities of hardwood sawtimber: the Lake States, Northern Appalachian Mountains (Northern Mountains), and Southern Appalachian Mountains (Southern Mountains). Although this...

Bird species distribution and predation rates on natural and artificial nests were compared among unmanaged mature, shelterwood, and clearcut northern hardwoods forest to evaluate the effect of these practices on bird populations. Twenty-three of the 48 bird species detected during the study differed significantly in abundance among unmanaged mature forest, shelterwoods, and clearcuts. Results of multiple regressions of bird abundance and habitat variables suggest that differences in bird species distribution among treatments were the result of differences in habitat structure among...

The eastern hardwood forests of the US may be threatened by the changing atmospheric chemistry and by changes in harvesting levels. Many studies have documented accelerated base cation losses with intensive forest harvesting. Acidic deposition can also alter nutrient cycling in these forests. The combination of increased harvesting, shorter rotations, and more intensive harvesting, along with the potential for N and S saturation due to changing atmospheric chemistry in the eastern US, raises concerns about the long-term productivity of these commercially important eastern hardwood forests....

Urban ecological systems present multiple challenges to ecologists—pervasive human impact and extreme heterogeneity of cities, and the need to integrate social and ecological approaches, concepts, and theory.

Mortality of sugar maple (Acer saccharum Marsh.) has reached unusually high levels across northern Pennsylvania since the early to mid-1980s. We evaluated the influence of glaciation, topographic position, foliage chemistry, defoliation history, and stand characteristics (species composition, structure, density) on the health of sugar maple in 43 stands at 19 sites on the northern Allegheny Plateau. Using percent dead sugar maple basal area as the measure of health, we found that all moderately to severely declining stands were on unglaciated summits, shoulders, or upper backslopes. Stands...

Cell suspension cultures of Dutch elm disease (DED)-tolerant and DED-susceptible American elms clones have been established and characterized as prerequisites for contrasts of cellular responses to pathogen-derived elicitors. Characteristics of cultured elm cell growth were monitored by A700 and media conductivity. Combined cell growth data for all experiments within a genotype showed relatively low variances and between-genotype contrasts during repeated passages showed no significant differences. Subculturing exponentially growing cells at 8-14 day intervals, within readily measured...

Current-year red spruce (Picea rubens Sarg.) foliage is predisposed to winter injury by one or more types of anthropogenic pollutants, particularly acidic deposition. The resultant defoliation, when severe and repeated, leads to dieback and eventual mortality of affected red spruce individuals