Study of Distance Sampling Methods Accuracy to Estimation of Mediterranean Stinkbush Species (Anagyris Foetida L.) Density (Case Study: Forests of Kasakaran, Gilanegharb)

The nearest individual method (NIM), Nearest neighbor method (NNM) and compound method (CM) are distance sampling methods that are being applied to measure the plant density (numbers of individuals per unit area). Density is one of the essential structural characteristics in forest stands and useful to understand the dynamics of the forest. The present study aimed to find the most adaptable distance sampling method to estimate the density (numbers per hectare) of Mediterranean stinkbush species ( Anagyris foetida L.) and to compare the results at the methods with the results of 10 m2 circular sample plots using the accuracy criterion. In the Kaseh-Karan district of Gilan-Gharb in the Kermanshah province in a 50-hectare area, 50 sample points in 100 meters * 100 meters grid dimensions were considered using the systematic random pattern. then, at each sampling point, the mentioned distance sampling methods and 10 ar circular method were performed, and the required features of all of the Mediterranean stinkbush species were measured and recorded. According to the circular sample plot methods and different formulas, the density of Mediterranean stinkbush species was calculated SPSS was used in order to stastical analysis. Finally, the distance and circular methods were compared using the accuracy criterion attained from the results of density estimating formulas.
Results showed that in order to estimate the density of the investigated species with regards to the acceptable accuracy criterion to research activities(the accuracy less than ±10 percent) none of formula were suitable but for executive tasks (the accuracy less than ±25 percent), the most appropriate sampling method and estimating formula for Anagyris foetida L. species from among the above instances were the NIM with the Morisita and Byth and Ripley formulas and NNM with Byth and Ripley formula respectively.