Radial Variation and Its Effect on Sampling Efficiency in a Luanta Fir Tracheid Study

設置於台灣中部香杉種源造林地，値林齡25年生時，即於1998年4月下旬選取20株樣木，每株樣木由胸徑處，東側方向取3×2×2cm大小之木塊，每一木塊再進一步細分為各個年輪，但僅取靠近樹皮之最外5個年輪作為分析材料，俾探討管胞長徑向變化類型及其對管胞長取樣效率之影響情形。在靠近樹皮之最外層5個年輪之中，不論是早材、晚材或混合兩者管胞長一起分析，其管胞長保持約一定值。早材和晚材平均管胞長分別是3.53和4.07mm，其差異為0.54mm或約15％。然而，不同年輪間平均管胞長之範圍由3.67至3.86mm，其差異是0.19mm或小於6％。無論取最外層任何單一年輪或複數年輪組合（2到5年輪）均可提供一有效評估管胞長之方法。採用靠近樹皮部位生長錐樣本之有效性，在文中詳予討論。

關鍵字

巒大杉；細胞大小；取樣精度；徑向變異；生長錐樣品

並列摘要

Twenty Luanta fir (Cunninghamia konishii Hay.) trees of known seed sources at plantation age 25 were sampled from central Taiwan in late September 1998. A wood specimen of 3×2×2 cm was removed at breast height from the east cardinal direction of each sample tree. Each woodblock was separated further into individual growth rings, and only the 5 outermost growth rings near the bark were used to explore their radial variation pattern and its effect on sampling efficiency in a tracheid length study. Within the 5 outermost rings sampled near the bark, tracheid length was relatively constant regardless of whether earlywood or latewood tracheid or combined values were analyzed. The average tracheid length in the earlywood zone was 3.53 mm, and in the latewood zone was 4.07 mm. The difference was 0.54 mm or about 15%. However, average tracheid lengths ranged from 3.67 to 3.86 mm between growth rings, the difference being 0.19 mm or Less than 6%. Selected sampling of outermost growth rings either singly or in combination of any multiple of numbers (from 2 to 5 rings) provided an efficient evaluation of tracheid length. The validity of sampling only the partial increment core specimens near the bark is discussed.

並列關鍵字

Cunninghamia konishii ； cell dimension ； sampling precision ； radial variation ； increment core sample

國際替代計量

Radial Variation and Its Effect on Sampling Efficiency in a Luanta Fir Tracheid Study

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