Treesearch

An international conference on Environmental Influences on Tree and Stand Increment was held at the University of New Hampshire, Durham, New Hampshire, USA between September 23 and 27, 1985. The meeting included recommendations from a previous I.U.F.R.O. meeting in Vienna, Austria. Demands for forest resources are increasing but the forest land base is constantly decreasing. Timber supply can be increased by more effective management but it may also be decreased by insect and disease infestations or environmental influences (atmospheric deposition, drought, soil erosion, etc.). Due to the...

A multivariate regression model was developed to predict green board-foot yields for the common grades of factory lumber processed from yellow birch factory-grade logs. The model incorporates the standard log measurements of scaling diameter, length, proportion of scalable defects, and the assigned USDA Forest Service log grade. Differences in yields between band and circular headrigs were accounted for in the model. Lumber yields predicted using the model compared favorably with guidelines for expected yields from factory-grade logs. The coefficients presented here can be used in computer...

Multivariate regression models were developed to predict green board foot yields for the seven common factory lumber grades processed from white, black, and chestnut oak factory grade logs. These models use the standard log measurements of grade, scaling diameter, log length, and proportion of scaling defect. Any combination of lumber grades (such as 1 Common and Better) or total yield from a log can be predicted with these models. The coefficients presented here can be used in computer programs related to sawmill simulations, economic modeling, or log-yard inventory systems.

The effect of starvation on the feeding rate of larval Chaoborus (Diptera. Chaoboridae) was investigated using Daphnia rosea as prey. The starvation period varied from 12 h to 22 days. The starved Chaoborus were individually incubated with 10 Daphnia under controlled light and temperature conditions. Observations were made on prey mortality every 2 h for the first 12 h and once after 24 h. Feeding rates gradually increased to a maximum between 7-11 days of starvation. After this period, feeding rates declined to previous low levels. Generally, feeding rates were significantly higher during...

Quadratic and cubic polynomials, and Gompertz and Richards asymptotic models were fitted to yellow poplar growth data. These data included height, leaf area, leaf weight and new shoot height for 23 weeks. Seven growth analysis variables were estimated from each function. The Gompertz and Richards models fitted the data best and provided the most accurate derived variables. However, the Richards model was more complex to fit.

Under clear skies, a mid-sized sugar maple tree (Acer saccharum Marsh.) reduced irradiance in its shade on a south-facing wall by about 80% when in leaf, and by nearly 40% when leafless. Reductions by a similar-sized London plane (Platanus acerifolia W.) were generally slightly smaller. The percentage reductions varied with the fraction (DR) of diffuse radiation, and could be approximated by regressions with DR2 as the independent variable. The significance of the irradiance reductions (or building radiation climate was tested by using physical models of representative tree crowns (similar...

In conventional buildings, trees increase, decrease, or have little effect on energy use depending on general climate, building type, tree species, and tree location. Tree arrangements that save energy provide shade primarily for east and west walls and roofs and wind protection from the direction of prevailing winter winds. Particularly for buildings specially designed to use solar energy and those with solar collectors. it is important to place tree crowns so they do not block sun from collectors and south walls. But conventional houses also benefit from winter sun. Deciduous trees...

Differences in herbaceous competition, growth, soil, and foliar nutrient levels were compared for black walnut (Juglans nigra L.) saplings growing on an upland and a bottomland site in southern Illinois, with covers of five different herbaceous legumes or naturally occurring forbs. Hairy vetch ( Vicia villosa Roth. ) increased walnut height and diameter growth on both sites when compared to walnut growing in the naturally revegetated plots. Growth trends in the other four covers were mixed. All five legumes suppressed growth of other herbaceous vegetation for one or more summers. Only...

Data from select time and motions studies and a forest model plot, used in a simulation model, show that logging managers planning felling, bucking, and limbing for a cable yarding operation must consider the effect of alternate bucking rules on wood wastage, yarding production rates and cost, the number of choker to fly and total logging costs. Results emphasize then need to consider initial logging activities in terms of effects on cable yarding system efficiencies and wood wastage. Results also emphasize the need to match payload (piece size) to cable yarder capacity. Results suggest...

Logging cost simulators and data from logging cost studies have been assembled and converted into a series of equations that can be used to estimate the cost of logging young-growth coastal Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) in mountainous terrain of the Pacific Northwest. These equations were developed for two small cable yarders and one medium-sized yarder and are applicable for harvests of timber from 6 to 24 inches in diameter on slopes of 10 to 50%. Cost components can be easily calculated on a hand calculator. A computer pogram that can be adapted to...