Efficiency of distance methods of density measurements in four plant species in Karsanak rangelands of central Zagros region - Iran

In order to compare the distance methods of density measurement, a field study selected in Karsang located on the north-western area of Shahrekord (ChaharMahal and Bakhtiari province) to 32,000 m2 (200×160) and divided into eight sections of 4000 m2 (100×40).There was one transect with100 meters length in each area that we identified 10 points randomly within 10 meters of each other. The distance methods density measurement included nearest neighbor, closest individual, Third closest individual, Random pairs, Point center quarter, Angle order, wandering quarter and Variable area transec. Selected species were Astragalus effuses, Eryngium billardieri, Astragalus rodoseminus and Astragalus verus. Hopkines and Eberhardt indices were used to determine of distribution pattern in plants. In order to verify the obtained density, the relative difference of estimated density in each method to control group was calculated (Density estimation error in each method). Also Duncan’s mean separation test was used to compare the accuracy of methods and using standard deviation and measurement time, the method efficiencies were calculated. The results showed that the variable transect, nearest neighbor and closest person methods are more effective considering the time as a Indicator and Third closest individual and Nearest neighbor are higher than other methods considering accuracy criterion. Finally, if the selected criterion is precision, we can clearly take the Variable area transect as the most efficient.