Treesearch

Using the Scenic Beauty Estimator (SBE) approach, near-view color photographs were taken of 25 forested sites exhibiting gypsy moth induced tree mortality from 6% - 97%. A quadratic function of tree mortality by preference rating best described the variability in ratings ( R2 = .60). The effect of flowering mountain laurel flowers was also significant with the covariate "presence of flowers" increasing the R2 to .74. Scenic preferences and appeal for visitation increased initially as mortality approached 20-30%. Up to this point, increased sunlight, visual penetration, and understory...

The problem of identifying the scenic value of forest attributes and management plans is empirically explored. A sample of hardwood forests in Wisconsin, representing a diversity of management histories, is analyzed through photographs and field inventories. Scenic beauty judgements of the photographs by a diversity of respondents yield general scenic beauty estimates for the sampled forests. A general model is reported for predicting these estimates from forests' structural attributes. This model is then used to isolate and identify the marginal scenic impacts of single critical forest...

Ten tracts in the mountains of western Virginia were intensively sampled to determine the type and extent of soil disturbance from ground-based logging and the attendant erosion risk. Average slopes for the tracts ranged from 21 to 43 percent. Logged slopes exceeded 50 percent. All tracts surveyed were logged prior to the push for voluntary Best Management Practices and had been completed at least three months before the survey was conducted.Two logging methods were observed: skidding overland directlry from stump to roadside, and the use of bladed skid trails.

Needle blight of larch caused by Mycosphaerella laricina seriously limits the productivity of susceptible trees in the north central and northeastern United States. Adventitious shoots, derived from cotyledon tissue culture, of selected European larch (Larix decidua) and a hybrid larch were inoculated in vitro with three isolates of M. laricina.

Various inhibitors of polyamine biosynthesis were used to study the role of polyamines in DNA synthesis and cell division in suspension cultures of Catharanthus roseus (L) G. Don. Arginine decarboxylase (ADC; EC 4.1.1.19) was the major enzyme responsible for putrescine production. DL α-difluoromethylarginine inhibited ADC activity, cellular putrescine content, DNA synthesis, and cell division. The effect was reversible by exogenous putrescine. Ornithine decarboxylase (ODC; EC 4.1.1.17) activity was always less than 10% of the ADC activity. Addition of DL α-difluoromethylornithine had no...

Changes in the activites of S-adcnosylmethionine (SAM) synthetase (methionine adenosyltransferase, EC 2.5.1.6.) and SAM decarboxylase (EC 4.1.1.50) were studied in carrot (Daucus carota) cell cultures in response to 2,4-dichlorophenoxyacetic acid (2,4-D) and several inhibitors of polyamine biosynthesis. Activity of SAM synthetase increased significantly during the first 5 days of culture under all conditions, maximum activity being observed in thc presence of 2,4-D. DL-α-Difluoromethylarginine (DFMA), I,L-α-difluoroinethylornithine (DFMO) and cyclohexylammonium sulfatc (CHAS) had little...

A 50-year-old Allegheny hardwood stand in which the crown canopy had stratified into distinct species groups was thinned to 60% relative density leaving dramatically different stand structures and species composition. Treatments included combined thinning, thin from middle, thin from above, thin from below, and unthinned control. Individual tree growth was stimulated most by thinnings that created openings in the main crown canopy and still retained adequate numbers of the larger stems of the faster growing species. Thinning from below, which removed primarily noncommercial saplings and...

The life history of Stelidota octomaculata (Say) was studied in Ohio and Pennsylvania. This insect damages acorns and affects the establishment of oak seedlings. Acorns deployed in wire cages and pitfall traps plus a sampling of naturally occurring acorns were used to monitor insect activity. AdLllts overwinter in forest litter and begin feeding on undamaged germinating or damaged acorns in March. Acorns damaged by the beetles may fail to produce seedlings. Beetle reproduction occurs in spring and early summer inside acorns both above and below ground. Reproduction ceases in late July to...

Describes a distance-independent individual-tree diameter growth model for the Northeastern United States. Diameter growth is predicted in two steps using a two parameter, sigmoidal growth function modified by a one parameter exponential decay function with species-specific coefficients. Coefficients are presented for 28 species groups. The model accounts for variability in annual diameter growth due to species, tree size, site quality, and the tree's competitive position within the stand. Model performance is evaluated using the mean predicted error and the root mean square error. Results...