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The nonindustrial private forest sector controls 58 percent of the nation’s commercial forest area. Timber output from the NIPF has been a major forest policy issue throughout this century. A long-run regional timber output projection model was developed for the NIPF sector. The model was based upon two key assumptions: (1) forest management intensity and timber output are inversely related to the forest landowner’s alternative rate of return, and (2) for the NIPF sector, the alternative rate of return is inversely related to the size of forest holding. The timber output model was based on a cross-classification of NIPF land by its physical characteristics (e.g., forest type) and economic characteristics (e.g., landowner’s alternative rate of return). The stratification objective was to create strata with a uniform timber output response to changes in the above characteristics. If the total forest resource is thought of in terms of a matrix, each characteristic serves as a stratification dimension, creating a matrix composed of “homogeneous timber output response cells.” The values of each cell can be used as observations in a regression analysis projecting NIPF timber output. For the NIPF, the size of forest holding would be a primary stratification dimension. Due to the relationships described above, stratification by size of forest holding constitutes stratification by the landowner’s alternative rate of return. Also, since the forest resource is physically uniform, the expected rate of return (marginal value growth percent) of the forest will be uniform within a cell. NIPF landowners base their timber output decision on the relationship between the expected and alternative rates of return, resulting in a convenient forest policy analysis tool. The model was applied to a study region, Virginia’s Coastal Plain, with satisfactory results.

Measurements of DBH, upper diameters, merchantable height and total heights were made on 80 standing white oaks (Quercus alba) which were then felled for detailed measurements of the same parameters. The data obtained were used to evaluate the accuracy of standing tree measurements, to develop and compare volume equations that used upper diameter as one of the predictor variables and to examine the contributions of individual predictor variables to total volume prediction bias and precision. Relative bias ranged from 0.85% for DBH measurement errors to 2.88% for total height measurement errors. Relative standard deviation ranged from 1.52% to 10.13% for DBH and total height errors respectively. When both bias and precision ( standard deviation ) were considered jointly, the relative root mean squared error ranged from 1.75% to 10.48% for DBH and total height errors respectively. Upper diameter and merchantable height showed negative bias. A comparison of eight fitted models against the combined variable model revealed a gain in precision and a reduction in bias for models that used upper diameter as a third predictor variable. The improvement as based on the relative root mean squared error ranged from 28.8% to 71.3% for taped measurements. However, models that used upper diameter as a substitute for either DBH or merchantable height performed worse than the combined variable model. An analytic examination of the impact of measurement error on volume prediction bias showed that merchantable height errors accounted for most of the bias and that DBH and upper diameter errors contributed almost equal amounts(in absolute terms) to the volume bias.

Nine taper equations were tested to predict diameters inside bark along the stem for Pinus oocarpa Schiede trees growing in natural stands of central Honduras. A five parameter submodel predicted as well as an eight parameter model proposed by Kozak, 1988. Taper variation was explored between two geographic regions from which trees with different taper were suspected. Results showed that different site classes, not fully accounted for in the model, might have an effect on the prediction of taper in each region. Also, the effect of crown class and live crown ratio on prediction was evaluated. The model selected exhibited different prediction patterns for dominant and suppressed trees. On the other hand, live crown ratio did not appear to affect prediction. A computer program was written to use the taper equation developed to compute total and merchantable volume to different top diameter limits.

During a week-long North Carolina Forestry Camp for Farm Boys, more than 80 carefully selected vocational agriculture students from across North Carolina visited Camp Hope. The boys learned good forestry practices including planting trees, selecting and marking trees for cutting, identifying tree diseases and insects, preventing fires, and more. In this photograph, Charles E. Millwood of the International Paper Company, leads a discussion on timber estimating. Jack Holland, of International , observes at left. More information about this photograph can be found in Champion publication The Log. Click the link in the “Related Materials” field to view the article on pages 6 - 7.

During a week-long North Carolina Forestry Camp for Farm Boys, more than 80 carefully selected vocational agriculture students from across North Carolina visited Camp Hope. The boys learned good forestry practices including planting trees, selecting and marking trees for cutting, estimating volumes of standing and logged trees, identifying tree diseases and insects, preventing fires, and more. More information about this photograph can be found in Champion publication The Log. Click the link in the “Related Materials” field to view the article on pages 6 - 7.