Category: Ecological Research
Title: Slope Correction of Plot Dimensions for Vegetation Sampling in Mountainous Terrain
Author: * Abella, S.R., Gering, L.R., Shelburne, V.B.
Subject: Slope, Vegetation gradients
Abstract: Tree basal area and density are criteria used to define plant communities, set conservation priorities, and evaluate management activities (Keddy and Drummond 1996, White and Lloyd 1998). Accurately estimating basal area and density from plots on a range of terrain consisting of different slope gradients is a common goal during ecological field studies. For a plot of given dimensions, the area of the plot on a horizontal plane decreases as slope gradient increases. For example, a 20 x 50 m plot on flat terrain has a 0.1 ha horizontal area, while on a 60(percent) slope gradient, the same plot has only a 0.086 ha horizontal area. Unless plot dimensions are corrected for slope gradient, ecological field studies will underestimate basal area and density per unit area on a horizontal plane (Husch et al. 1982). Basal area and density estimates are not directly comparable between ecological studies that correct for slope gradient and those that do not, and slope corrections should be applied if resources are to be mapped. ...
Source: Natural Areas Journal