台灣南部南仁山迎風與背風分布樹種葉片耐脫水能力及比葉重的比較

Comparing Dehydration Tolerance and Leaf Mass per Area between Tree Species Inhabiting Windward and Leeward Sites of Nanjenshan Forest in Southern Taiwan

郭耀綸(Yau-Lun Kuo) ； 李彥屏(Yan-Ping Lee)

《台灣林業科學》 18卷4期 (2003/12) Pp. 283-292

https://doi.org/10.7075/TJFS.200312.0283

摘要

台灣南部南仁山森林迎風及背風生育地，因受東北季風影響程度不同，致樹種組成及森林形相截然不同。本研究藉測定9種迎風樹種，9種背風樹種，以及5種廣泛分布樹種的細胞膜電解質滲漏量，計算成損傷指數，由此代表各樹種葉部的耐脫水能力。所有樹種也測定比葉重。結果發現迎風樹種的葉片為硬葉，比葉重在14-24 mg cm^(-2)，遠大於背風樹種的5-9 mg cm^(-2)。葉片在水逆境條件下，迎風樹種比背風樹種有較低的損傷指數，顯示前者有較高的耐脫水能力。在這23種樹種中，背風樹種的水同木、紅果控木及山龍眼損傷指數最高，而迎風樹種的大頭茶及大明橘損傷指數最低。廣泛分布種的比葉重及耐脫水能力均介於迎風及背風樹種之間。本研究也發現供試23種林木的比葉重與葉片耐脫水能力有顯著正相關。迎風樹種具有高比葉重的硬葉，在結構上似可減少強風對葉片的物理性傷害，在生理上也具較高的耐脫水能力，此兩特性可能是迎風樹種能善處南仁山迎風環境條件的重要功能。

關鍵字

電解質滲漏 ； 損傷指數 ； 東北季風 ； 硬葉 ； 風逆境

並列摘要

Species composition and forest physiognomy at windward sites and leeward sites of Nanjenshan Forest, southern Taiwan, distinctly differ due to the differential impacts of wind stress produced by the northeasterly monsoon. In this study the membrane electrolyte leakages, expressed as injury indices, of 9 windward species, 9 leeward species, and 5 ubiquitous species were determined and used as measures of dehydration tolerance. The leaf mass per area (LMA) of these species was also measured. The windward species had sclerophyllous leaves with LMA values between 14 and 24 mg cm^ (-2). LMA values of the leeward species were between 5 and 9 mg cm^ (-2) only. When subjected to water stress, leaves of the windward species exhibited lower injury indices than leaves of the leeward species, indicating that the windward species had higher dehydration tolerance. Leaves of the leeward species, Ficus fistulosa, Helicia formosana, and Dysoxylum hongkongense, exhibited the greatest injury indices; in contrast, those of the windward species, Gordonia axillars and Myrsine sequinii, showed the least injury indices among all species tested. Dehydration tolerance and LMA values of the 5 ubiquitous species were between those of the windward and leeward species. In addition, a positive, significant relationship between LMA and dehydration tolerance of the 23 species was found. Sclerophyllous leaves of the windward species with relatively higher LMA values seemed to be able to reduce physical damage produced by the monsoon winds, and physiologically enhance dehydration tolerance. Both characteristics may play important roles in the ability of windward species to cope with windward environmental conditions in Nanjenshan Forest.

並列關鍵字

electrolyte leakage ； injury index ； northeasterly monsoon ； sclerophyll ； wind stress