A new sampling method in the Zagros forests using GIS (case study: Ilam forests of Iran)

Abstract

One of the basic parameters in forest management planning is detailed knowledge of growing stock, information collected by forest inventory. Sampling methods must be accurate, inexpensive, and be easy to implement in the field. This study presents a new sampling method called branching transect for use in the Iranian Zagros forests and similar forests. Features of the new method include greater accuracy, easy implementation in nature, simplicity of statistical calculations, and low cost. In this method, transect is used, which includes some sub-transects (side branches). The length of the main transect, side branches, number of trees measured in each side branch, and the number of sub-branches in this method are changeable based on homogeneity, heterogeneity, and density of a forest. In this study, based on the density and heterogeneity of the forest area studied, 20-m transects with four and eight side branches were used. Sampling plots (Transects) in four inventory networks (100 m × 100 m, 100 m × 150 m, 150 m × 150 m and 100 m × 200 m) were implemented in the GIS environment. The results of this sampling method were compared to the results of total inventory (100% count) in terms of accuracy, precision (t-test), and inventory error percentage. Branching transect results were statistially similar to total inventory counts in all cases. The results show that this method of estimating density and canopy per hectare can be used in Zagros forests and similar forests.