Penyusunan persamaan penduga volume pohon kelompok jenis Dipterocarpaceae di PT Timberdana Kalimantan Timur

Abstract

Tree volume estimation especially standing tree, still a practical problem for the forester. Tree volume table is a common way to describe the relation between tree volume and its estimation variables (tree diameter or height). Berkhout model (V = aDb ; where : V = volume, D = diameter breast height, a dan b = constans) is a simple tree volume estimator because only use single variable which is tree diameter (D). It is one of many models with clear thought structure, mathematically derivated from cylinder volume using form factor (Suhendang 1993). Berkhout model is a non linear model which usually it should be transformed to linear model using logaritmic transformation to find regression constans. Statistical softwares development today, made that’s a problem no more. This research aims (1) to find better accuracy for tree volume estimation using Berkhout model, by transformation or without transformation; and (2) to find the best tree volume model for dipterocarpacea in PT Timberdana Kalimantan Timur. Data used in this research consist of 96 tree samples of dipterocarpaceae in PT Timberdana, East Kalimantan. Data divided into two data sets for model building (63 tree) and validation (33 tree). Data used in this research gives that Berkhout model equation built using transformation to linear model (V = 0.000411D2.214) has a better accuracy than model without transformation. The best tree volume equation of dipterocarpaceae in PT Timberdana is exponential association model, expressed by the equation : V = -3.920*(1.386  e-0.0142D), while Berkhout model is in second place together with quadratic fit and sinusoidal fit models.