The most appropriate distance sampling method to determine density and percentage of canopy cover in Juniper forests

Juniperus excelsa forests are thinner and have distribution in areas with severe living conditions andcompletely rocky beds. Due to inventories of these forests are hard, costly, and time-consuming,therefore, in this study, the most suitable sampling method was investigated to determine the density andpercentage of canopy cover in Juniper forests. For this purpose, an area of 15.9 ha of forests in Alborzprovince made an inventory with a full callipering method. The results of full callipering show thatdensity is 61 trees per hectare, and the percentage of canopy is 20.51 in this stand. In the next stage, sitestudy was made an inventory by using seven distance sampling methods (nearest individual method,nearest neighbor method, second nearest neighbor, random pairs method, T-square method, and pointcentered quarter method), density and percentage of canopy were calculated for each method andcompared to Full callipering method. Results show that random pairs method estimated density 58.3 treesper hectare (the difference is -3.79 percent) and T-square method estimated density 62.97 trees perhectare (the difference is +3.91 percent) has less difference in estimating trees density. The random pairsmethod estimated canopy cover 23.4 percent (the difference is 14.09 percent), and is the lowest error toestimate the percentage of the canopy in these forests. According to the specific condition of Juniperforests, using a random pairs method is suggested because it can be easily measured, has less error andsaving time and money.