In this study, the authors present a set of height-diameter equations for 13 riparian tree species using data obtained from bottomland hardwood forests along the Mississippi, Missouri, Illinois, and Des Moines rivers. Nonlinear regression techniques are used to develop the equations. The resulting equations provide a reasonable means of predicting unknown tree heights, given DBH, for these species (from Abstract).
The prediction of the diameter distribution of a stand is of great interest to forest managers for the evaluation of forest resources and scheduling the future silvicultural treatments. This paper describes geostatistical approach for the prediction of diameter distributions. Use of this method make possible to estimate the diameter distribution at locations, where no secondary variables are measured.
The usual practice of measuring diameter at 4.5 feet (1.3 m) or DBH is meaningless in wetland tree species such as bald cypress (Taxodium distichum (L.) Rich.), due to the presence of fluted basal swells. Since buttress dimensions usually have no consistent relation to volume or form in the tree, the current practice among life-sciences professionals is to measure stem diameter 18 in (50 cm) above �pronounced� butt swelling. This measure is termed normal diameter (D,). This paper contrasts the use of six fixed-height diameter-measurement points ranging from 6 ft (1.8 m) to 11 ft (3.4 m) against D, (a variable-height measurement point) for predicting cubic volume.
Diameter and height relationship of the selected 6 coniferous species.
This paper illustrates the application of a mixture model to describe the bivariate diameter-height distribution of trees growing in a pure, uneven-aged beech forest. A mixture of two bivariate normal distributions is considered but the methodology is applicable to mixtures of other distributions. The model was fitted to diameter-height observations for 1242 beech trees in the protected forest Dreyberg (Solling, Germany). A second issue discussed in this paper is concerned with the general question of assessing the fit of models for bivariate data. It also shows how a device called �pseudo-residual� enables one to investigate the fit of a bivariate model in new ways and in considerable detail.
dernière mise à jour: lundi 15 novembre 2004