A Site Growth Model for <i>Pinus elliottii</i> in the Southern Cape
Abstract
SYNOPSIS A site requirement study was initiated to refine present knowledge of the site requirements of Pinus elliottii (slash pine) and aid decisions for species choice in the future. Growth models for predicting height growth in relation to site factors were developed for P. elliottii in the Southern Cape. Over 50 soil and site variables from 90 plots were used in the analyses. Two models were developed using (i) effective soil depth, (ii) natural log of effective soil depth, slope angle, terrain position and rainfall. Soil available phosphorus was found to influence growth but was not used in the prediction models. Effective soil depth, which reflects soil moisture availability was found to be the most useful parameter for prediction of tree growth performance. Where the average effective soil depth is less than 400 mm a mean annual increment at 20 years of less than 4 m3/ha per annum can be expected, which is an uneconomical proposition for forest management.