مقايسه پنج روش اندازه گيري فاصله اي تعيين تراكم در بوته زارهاي تنگ لايبيد يزد

Comparison of five distance methods for estimating density on Shrub Communities in Tang-Laybid Yazd

Five distance sampling techniques used to estimate density for Artemisia aucheri and Cornulaca monacantha species in this survey include: point center quarter, closest individual, nearest neighbor, random pairs and angle order methods. Sampling was conducted within 3 (40 m x100 m) sampling areas selected in TangLaybid. 30 points were selected equidistant apart along 10 randomly located 100-m transects for measurement of distance within each sampling area. Density obtained by each method was compared to the total count in a randomized complete design and Duncanʹs test. Hopkines and Eberhardt indices were used to detect dispersion pattern of plants. The point center quarter method provided a reliable estimate of density for Cornulaca monacantha in the community with density of 0.381mʹ and a clumped distribution. The nearest neighbor method gave a reliable estimate of density for Artemisia aucheri in the communities with density of 1.8/mʹ and 2.91mʹ and a tendency toward uniformity. Results showed that the point center quarter method can give reliable results in shrub communities with cover around 10% and a clumped pattern while the nearest neighbor method can give a reliable estimate in communities with cover between 16-20% and a uniform pattern.