Comparing the Efficiency of Transects Length with a Statistical Method to Determine the Quantitative Characteristics of Watershed Forests in Olad -Ghobad, Lorestan province

Considering the current state of the Zagros forests and the necessity of using information related to quantitative characteristics in the management of these forests, it is essential to prepare more accurate information so that the control of this area can be done more accurately. One of the ways to obtain statistical information is linear sampling (transect.( In this regard, the present study aims to compare the efficiency of the length of transects with the inventory method and to investigate the performance of this method in forests with different densities.
To carry out the present research, taking into account the area and topography of the region, a square survey grid with dimensions of 100 x 100 meters was used in the customary forests of Olad -Ghobad located in Lorestan province. Then 30 one-hectare plots were implemented in the area and fully surveyed. In the next step, transect sampling was performed in two modes using tree position simulation in GIS. In the first step, transects with lengths of 25, 50, 75, 100, and 125 meters were harvested inside each one-hectare plot. Then, the quantitative characteristics of the trees that were placed along the desired tracts, such as two diameters perpendicular to each other, were measured. In the second stage, the forest area was divided into three classes low density, medium, and dense, and again transects with the studied lengths were created again. Quantitative characteristics of trees were measured on transects in each class. The results of characteristics comparing the number of trees per hectare and canopy cover showed no significant difference between different transect lengths with a full inventory. The results of estimating the E%2×T index in the study area showed that for both characteristics of the number of trees per hectare and canopy cover, a 25-meter transect with values of (19038.82) and (958338.9) have the highest precision, respectively. The results showed that the value of this index has the highest accuracy for medium numbers in hectare with 75 m transect length, and low canopy covers with transect length of 50 m.