Comparing the efficiency of distance and quadrate indices in determining Artemisia sieberi and Astragalus ammodendron distribution pattern in Markazi province

This research compares the indices efficiency of Artemisia sieberi and Astragalus ammodendron distribution pattern in Markazi province. In the key area of each site 4 transects (100m) were established based on random- systematic sampling method. Vegetation sampling was performed along each of transects in 15 selected points. Distance indices included Johnson and Zimer، Eberhart، Pielou، Hopkines and Holgate were used in each point. The distance of understudy plants to nearest plant، distance among selected plant and its nearest neighbor، and distance between the point and the second plant was measured. Quadrate indices included Green، Lioyd، Morisita and Standardized Index of Morisita. In all 15 points، density parameter of selected species was estimated. Results showed A. sieberi distribution pattern has equally and، A. ammodendron has random with a tendency toward clumped pattern. The More was in equality of the species، the more in converging of distance and quadrate indices. However the accuracy of distance methods was more than quadrate methods. Generally، those vegetation types that distributed clumped pattern showed less efficient quadrate indices due to the problems of number، area and shape of quadrates. So، quadrate indices show higher tendency to random pattern.