The estimation of tree numbers of Sugi (Cryptomeria japonica) in Yakushima [Japan]

An investigation by strip sampling was conducted in Hanayama district, Shimo-Yaku Forest Region and Shiratani district, Kami-Yaku Forest Region. Total number of Sugi trees in Hanayama district, with the significant level of 5%, is equal to 19947.3 plus or minus 4587.5 stems (The total number for Hinoki, Tsuga and Momi trees are equal to 875.7 plus or minus 716.4 stems, 2723.8 plus or minus 1317.2 stems and 389.7 plus or minus 468.5 stems, respectively.) In Shiratani district, it was found that the total number of Sugi trees is equal to 18103.0 plus or minus 12278.2 stems (The total number Tsuga and Momi trees are equal to 1827.3 plus or minus 3117.2 stems and 548.9 plus or minus 625.7 stems, respectively.) The larger-size trees with DBH of 120 cm and above, was found to equal to 17 stems and 11 stems of them are Yakusugi (these are covering 8.3% and 5.4% of total number of 204 stems, respectively).