台灣肖楠3個不同種源50個天然授粉家系之試驗地於1976年設置於林業試驗所蓮華池研究中心，採逢機完全區集設計，每一列狀小區栽植7株，植距2×2m，4個重覆。當林齡27年生時，於每一個重覆中選取存活率100%之家系為取樣對象，計獲得30個家系，使用直徑10mm之生長錐，每一小區選取胸徑接近中間木一株，於胸高部位(1.3m)東側鑽取一木蕊，共120個木蕊（1木蕊／家系／小區×30家系×4重覆）。然後由每一木蕊取最靠近樹皮側之6個年輪做為評估木材比重和管胞長之對象，探討不同種源間和種源內家系間之變異。結果顯示兩個性狀在不同種源間無顯著差異，但種源內家系間比重呈顯著之差異，而管胞長則否，兩種性狀在樹和樹間之變異量約佔總變異量之80%。比重和管胞長總平均分別為0.494和3.16mm，估算之家系遺傳力，管胞長為0.296，小於比重之0.412。據此加以討論將來後續之不同策略的選育計畫。
A test plantation containing 50 wind-pollinated progeny families representing 3 provenances of Taiwan incense cedar (Calocedrus formosana) was established in central Taiwan in 1976. A randomized complete block design was adopted in the field layout with 7-tree linear plots in each of 4 replications and a 2×2-m spacing between plants. At a tree age of 27 yr, a 10-mm caliber increment core sample was extracted at breast height in the east cardinal direction from the mid-DBH size tree per plot. Thirty families (out of 50) with 100% survival of trees in each of 4 replications were selected for increment-core extraction. In total, 120 cores (1 core family^(-1) plo^(-1)×30 families×4 replications) were sampled. From each core, only the 6 outermost growth rings near the bark were used to assess the specific gravity and tracheid length. Variations among provenances and among families within a provenance were analyzed using a general linear model. No significant difference among provenances was found in either trait. Significant variations among families within provenances were detected at the 5% level for specific gravity but not for tracheid length. Tree-to-tree variations in both traits accounted for more than 80% of the total variances. The overall mean values were respectively 0.494 for wood specific gravity and 3.16 mm for tracheid length. The family heritability estimate for tracheid length was 0.296, which was weaker than that for wood specific gravity (0.412). Therefore, different strategies of future selection programs are discussed.
