多納地區台灣杉與台灣赤陽人工混淆林生長競爭之研究

Growth Competition in Mixed Plantations of Taiwanian and Red Alder in the Duona Area

汪大雄(Dar-Hsiung Wang) ； 王兆桓(Chao-Huan Wang) ； 高毓斌(Yui-Bing Kao) ； 吳楊浚(Yang-Jan Wu)

《台灣林業科學》 19卷4期 (2004/12) Pp. 337-351

https://doi.org/10.7075/TJFS.200412.0337

摘要

與單純林分相比較，混淆林不但可以改善物種的歧異度，增強林木對環境變化、污染和病蟲害之抵抗力外，還具有改善土壤性質，增加林地生產力的優點。然而，混淆林分內各樹種間之競爭對未來各樹種數量之消長具有關鍵性之影響。本研究使用不同混淆比例之台灣杉與台灣赤楊混淆人工林，以單木生長之觀點，探討混淆林分內樹種間之生長競爭。試驗地於1997年設置在行政院農業委員會林業試驗所六龜試驗林多納地區之人工混淆林內，台灣杉與台灣赤楊栽植行比例為1:0, 3:1, 2:1, 1:1及0:1等五種混合方式，栽植距離為2*2m。因受地形限制，本研究採用不等重複取樣，設置16個永久樣區進行長期監測。造林地10年生之調查資料顯示在樹種競爭方面以台灣赤楊佔主優勢地位，其平均樹高與平約胸徑約為台灣杉之2倍。對個別樹種而言，不同混淆比例問之平均樹高與平均胸徑皆無差異，但是，16年生之資料顯示台灣杉平均樹高與平均胸徑都有隨著台灣杉混淆比例增加而增加之趨勢。此外，就台灣杉與赤楊混淆林觀之，可以明顯看出從1997至2003年期間，在各種混淆比例下，台灣杉生長速度均比赤楊要來得快。雖然如此，但就目前而言，台灣赤楊對於林分林木生長競爭之影響仍大於台灣杉。後續之調查，則有助繼續於了解不同混淆比例對此兩樹種間生長競爭之影響。

關鍵字

混合林 ； 歧異度 ； 生長競爭

並列摘要

Compared with pure stands, mixed stands not only increase the degree of species diversity and build up trees' resistance to environmental stresses, atmospheric pollution, diseases, and pests, but also improve soil properties to enhance the productivity of stands. However, competition among species in mixed stands can critically influence the future amount of trees of each species. In this study, mixed plantations of Taiwania (Taiwania cryptomerioides Hayata) and red alder (Alntis formosana Makino) were used to model the growth and competitive interactions between these 2 species based on an individual tree approach. The mixed proportions of Taiwania and red alder designed in planting were 1:0, 3:1, 2:1, 1:1 and 0:1, respectively. Due to restrictions of the terrain, an unequal replication sampling scheme was adopted, and 16 permanent plots were installed for subsequent monitoring. The survey of 10-year mixed plantations showed that due to its growth advantage, partially because of its nitrogen-fixing ability, the red alder had more rapid early growth in height and DBH than Taiwania, thus, it dominated the stand in the early stage with averages of height and diameter twice those of Taiwania. There were no significant differences among the averages of either height or diameter for stands with different mixed proportions of each species. However, 6 years later, the average in height and diameter of Taiwania were increasing with an increase in percentage of Taiwania in the mixed plantations. Data collected in 2003 showed that during the past 6 years, Taiwania grew more rapidly than red alder in both DBH and height. Thus, it may be possible for Taiwania to overtake red alder and emerge into the overstory in the future. However, the influence of red alder on growth and competition in the mixed stands still ranks first at this moment. Further surveys will be helpful to investigate the stand dynamics patterns of mixed stands.

並列關鍵字

mixed stands ； species diversity ； growth and competition