TITLE:
Practical Implications of Ignoring Slope When Conducting Timber Appraisals of Longleaf Pine Plantations
AUTHORS:
Curtis L. Vander Schaaf
KEYWORDS:
Variable-Radius, Stumpage, Forest Inventory, Pinus palustris, Sampling
JOURNAL NAME:
Open Journal of Forestry,
Vol.16 No.3,
May
29,
2026
ABSTRACT: Horizontal point sampling is commonly applied during forest inventories. A problem widely known is the error associated with probabilities of selection when projecting horizontal angles along the slope of a site. However, to date, the impacts of not accounting for slope when using horizontal point sampling on timber appraisals has been minimal. This study quantified the potential impacts on timber appraisals when failing to account for slope for two common English Basal Area Factors (BAF) of 10 (2.296 metric) and 20 (4.592 metric). When percent slope exceeds 15% the impacts can become meaningful and hence foresters should make sure to address this issue when conducting appraisals. For stands of ages 20 and 30, and for optimistic stumpage prices of $20, $30, and $45 per ton of pulpwood, chip-n-saw, and sawtimber, respectively, projecting angles along 20% slopes were found to reduce appraisals ranging from around 3.6% to 3.9%. When projecting angles along 30% slopes appraisal reductions ranged from around 7.6% to 8.2%.