建立造林樹種健康林苗生產專區(1/4)

本研究調查臺南市新化林場以及嘉義縣澐水工作站小葉桃花心木母樹生長資料，結果發現新化林場小葉桃花心木生長較好，平均DBH 94.5 cm，平均樹高23 m。於小葉桃花心木育苗中發現，其種子苗有大葉、中葉及小葉三種不同形態差異，苗齡約30個月的苗木，平均苗高大葉型態苗木(85.6±17.6 cm)及小葉型態苗木(86.9±15.6 cm)相差不多，但平均地徑大葉型態苗木(14.5±0.1 mm)則明顯高於小葉型態苗木(10.5±3.2 mm)。桃花心木每年4~5月開花，翌年3~4月果實成熟種子可直接播種在容器中，如需儲藏，應將種子含水率降至5%左右，並儲藏在0℃以下低溫環境。一般桃花心木苗木最適合出栽為苗齡22個月，苗高在50-88 cm，地徑在8.2-11.8 mm，纖弱指數<7.5範圍內。桃花心木新植造林木易受風害作用，因此出栽造林之苗木應選擇纖弱指數較小，根系健全者為佳，如此便可提高造林木成活率。

This study investigated the growth of Swietennia mahagoni mother trees in Shinhua National Forest Arboretum and Taiwan Forestry Research Institute Yunshui Workstation. The result shows that the average DBH was 94.5 cm, and average height of tree was 23 m in Shinhua National Forest Arboretum, it was better than that in Yunshui Workstation. We found that Swietennia mahagoni seedlings were big leaves, medium leaves and small leaves three different appearance types. It was not significant differences of average height of 30 month age in big leaves seedling (85.6±17.6 cm) and small leaves seedling (10.5±3.2 mm), but the ground diameter, big leaves seedling (14.5±0.1 mm) was significant bigger than the small leaves seedling (10.5±3.2 mm). Mahogany flowering during April to May, and the fruit ripening during March to April next year. Mahogany seeds could direct be sown in vessels, and should be stored in moisture content 5% and temperature under 0℃. Mahogany seedlings at 22 month age, seedling height between 50-88 cm, ground diameter between 8.2-11.8 mm, and Sturdiness Quotient under <7.5 were fit to be planted. Because Mahogany new planting trees easy being damage by wind, so we should choose the seedlings that Sturdiness Quotient smaller and roots were health and complete to plant. It could raising the survival probability of planting.