Silvicultural Growth Performances of Thirteen Endemic Broadleaf Trees of Taiwan

13種原生闊葉樹造林生長表現

游漢明(Han-Ming Yu) ； 馬復京(Fu-Ching Ma) ； 許原瑞(Yen-Ray Hsu) ； 張乃航(Nai-Hang Chang) ； 洪富文(Fu-Wen Horng)

《台灣林業科學》 23卷3期 (2008/09) Pp. 255-270

https://doi.org/10.7075/TJFS.200809.0255

摘要

為探討台灣原生闊葉樹種應用於復舊造林之生長潛力，1993年3月於台東太麻里研究中心，海拔800 m，坡向西南之林地進行原生闊葉樹塊狀混合造林。每一樹種栽植3~5區，每一小區栽植同一樹種50株，株行距2×2 m，共計13種樹種參試。定期調查與比較年度間造林木的樹高及胸徑生長差異，結果顯示杜英及香楠之生長及成活率均佳，在造林9年後，平均高生長分別達750及730 cm，平均造林成活率均維持在60%左右。其他的原生闊葉樹，除大葉杜樹高未達5 m外，包括鬼櫟、木荷、江某、三斗柯、牛樟等台灣中海拔闊葉樹種，其高生長雖稍遜於一般之闊葉樹種造林木如光臘樹，這些樹種平均高生長均達5 m以上，且平均胸徑達7 cm以上。各造林樹種在造林初期前三年之樹高淨生長表現，除台灣櫸可達約80 cm yr^(-1)之生長外，餘樹種之淨生長量皆在30~50 cm yr^(-1)之間，但至3~5年間，各樹種之樹高淨生長平均可達80 cm yr^(-1)，其中杜英更高達140 cm yr^(-1)，且此快速生長時期，可持續至第7.5年。顯示原生闊葉樹種應用於造林時，藉由良好的撫育管理下，在台灣中、低海拔林地極具造林潛力。
造林木初期生長均有分叉現象，且樹冠幅均達2 m以上，可能會影響造林木後續生長表現及木材形質利用，尤其造林木平均分叉率達40%，建議可提早造林木的修枝及疏伐小徑木，促進林分的健康生長。由樹高生長（應變數）與林齡（自變數）進行迴歸分析結果，迴歸係數(R^2)均在0.90以上，顯示此一元二次迴歸方程式可用於林木初期生長之預測。

關鍵字

原生種 ； 闊葉樹 ； 生長表現 ； 造林

並列摘要

We investigated the growth potential of some endemic broadleaf species used in restorative reforestation. In March 1993, mix-plot planting of the 13 test species native to mid-elevation forests of Taiwan was carried out in a tract situated at 800 m elevation with a southwest facing slope at the Taimali Research Center Taiwan Forestry Research Institute, Taitung, southeastern Taiwan. Each species was planted with 3~5 plot repetitions, and in each plot, 50 trees of the same species were planted with a 2×2-m spacing. A survey of sapling growth was carried out periodically, and tree forms were also investigated in later years. Results showed that common elaeocarpus (Elaeocarpus sylvestris) and incense machilus (Machilus zuihoensis var. zuihoensis) saplings had better growth performances and survival rates, and the respective mean height growth had reached 750 and 730 cm 9 yr after out-planting. Their survival rates all reached 60%. With the exception of Pasania kawakamii and Tricalysia dubia which did not reach 5 m in height, the mean height growth of the other indigenous broadleaf trees including Pasania ternaticupula, Schima superba, Schefflera octophylla, Lithocarpus castanopsisifolius, and Cinnamomum micranthum, all exceeded 5 m, although their growth was not as fast as some general plantation species such as Fraxinus formosana, and their mean diameter at breast height (dbh) growth all reached 7 cm. The net height growth of the studied species in the first 3 yr, was 30~50 cm yr^(-1), with the exception of Zelkova serrata which reached 80 cm yr^(-1). However, all species had net height growth exceeding 80 cm yr^(-1) during 3~5 yr, with E. sylvistris reaching 140 cm yr^(-1). The fast-growing period of the saplings among tree species lasted to 88 mo after out-planting. These results suggest that endemic broadleaf species have tremendous afforestation potential in mid- and low-elevation plantation forests of Taiwan. When coupled with good tending and management of the forests, even greater silvics potential can be realized.
Even in the early stage of growth, saplings often had forking tendencies with 2 m or more of crown width of planted trees, which may cause retardation of subsequent growth performance and may also influence the tree quality for timber utilization. In particular, as the average forking rate reached 40%, we deem that pruning and thinning of small-diameter logs should be scheduled to promote tree form quality. A correlated regression analysis of tree height growth and tree age indicated that 2-degree polynomial regression equations (R^2≥0.90) by tree age of tree species can be used to predict the early growth performance of planted trees at the site.

並列關鍵字

endemic species ； broadleaf ； growth performance ； silviculture