Practical implications of projecting a horizontal angle in a nonhorizontal manner to diameter at breast height.

摘要

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, the consequences of the slope created by projecting a horizontal angle to dbh from another height, such as eye height when it differs from 4.5 ft-whereby the angle is no longer horizontal-have not been widely appreciated. Although trivial in many cases, as basal area factor (BAF) increases, dbh decreases, the angle vertex height difference from dbh increases, and the length of the angle from the point to the tree decreases, the reductions in selection probabilities can become meaningful.