مقایسه پنج روش فاصله‌ای اندازه‌گیری تراکم در چند تیپ گیاهی فلور خزری

Primary information about different methods of vegetation sampling is important to researchers to decide about their sampling. In this study we applied five distance methods (closest individual, nearest neighbor, random pairs, point-centered quarter and angle orderd) to estimate plant density in three vegetation types including Artemisia sieberi, Juncus littoralis and Punica granatum in Mazandaran, Iran. Methods were compared according to their precision, accuracy, and efficiency. In each vegetation type total number of above dominant species (A. sieberi, J. littoralis and P. granatum) was counted in an area of 5000 m2 as actual density. Then five distance methods were applied under random-systematic sampling method. The results showed that in A. herba-alba angle orderd method had minimum coefficient variation (cv) but for J. littoralis closest individual and random pair methods showed minimum cv. For P. granatum the least cv was found in closest neighbor method. Based on the accuracy, for A. herba-alba and J. littoralis least standard error of the mean was found in three methods (closest individual, random pair, and point-centered quarter). Two of these methods (closest individual and point-centered quarter) showed also least standard error of the mean for P. granatum. For A. herba-alba all methods showed more or less the same efficiency but for J. littoralis closest individual and random pairs and for P. granatum closest neighbor had better efficiency than other methods.