Study on the effect of forest stand distribution pattern on results of different estimators of the nearest individual distance method

The Nearest Individual Sampling Method is one of the distance sampling methods for estimating density, canopy cover and height of forest stands. Some distance sampling methods have more than one density estimator that may be skewed to the spatial pattern. Unless the stands of the trees under study have a random spatial pattern. Therefore, the purpose of this study was evaluating the effect of spatial pattern of oak trees (Quercurpersica) on the results measurements of density, canopy cover and height by the nearest individual method in Char Zebar Olia Forests in Islamabad gharb of Kermanshah province. For this purpose, three stand were selected in the area and within each stand a 0.5 hectare plot was identified.. After sampling 100% and nearest individual sampling in each plot; Spatial pattern and density of trees were calculated with different estimators of nearest individual sampling method. The results showed that the spatial distribution pattern of trees was influenced on different estimators of nearest person density. According to the acceptable accuracy  for the research, the formula presented by Byth and Ripley for Plot No. 1 And the formula provided by Batchler& Bell are suitable for Plot No. 3 .For estimating the canopy cover percentage, the formulas presented by Byth and Ripley, Cottam et al and Morisita (1957) for Plot No. 1 and Morisitachr('39')s (1953) formula for plot No. 3 show better results than the other relationships. To estimate the tree height of the studied plots, the nearest individual sampling method in plots 1 and 3 based on acceptable accuracy  shows acceptable estimation.