Photosynthetic Capacity and Shade Tolerance of 180 Native Broadleaf Tree Species in Taiwan

台灣180種原生闊葉林樹種光合潛力及耐陰性

郭耀綸(Yau-Lun Kuo) ； 葉慶龍(Ching-Long Yeh)

《台灣林業科學》 30卷4期 (2015/12) Pp. 229-243

https://doi.org/10.7075/TJFS.201512_30(4).0002

摘要

瞭解樹種的耐陰性對苗木培育或造林樹種的選擇都很重要，然而林業界目前尚未針對眾多台灣原生樹種的耐陰性進行系統性的調查。本研究將台灣原生闊葉樹種栽植在屏東科技大學苗圃，在2009～2014年的雨季期間測定180種稚樹的光合潛力，藉此量化數據當作樹種耐陰性的生理指標，將這些樹種的耐陰性區分為五等級。為了檢驗藉各樹種光合潛力判斷耐陰性的適用性，我們邀請6位具野外經驗的樹木學專家填寫問卷，判定各樹種天然更新植株最常出現的光環境，比較專家意見與光合潛力判斷此180種樹種耐陰性等級的異同。結果發現，所有樹種光合潛力範圍在35.8~9.1 μmol CO_2 m^(-2) s^(-1)之間，最高的前5種分別為山芙蓉、苦楝、野桐、黃槿及構樹，最低者為菲島福木。參考專家意見，我們將光合潛力區分為（1）≧ 26.0；（2）25.9~21.0；（3）20.9~15.0；（4）14.9~12.5；（5）＜ 12.5 μmol CO_2 m^(-2) s^(-1)等五個等級，分別歸屬耐陰性第1、2、3、4、5級（先驅樹種、陽性樹種、中等耐陰樹種、耐陰樹種、極耐陰樹種）。供試180樹種根據上述光合潛力分級，歸類為耐陰性第1、2、3、4、5級的樹種分別有18、37、70、33、22種。專家意見對應上述五級光環境，由高光至低光分別有21、52、63、40、4種，專家意見認定的極耐陰樹種較少。此兩種判斷樹種耐陰性的結果，其皮耳森相關係數達0.92，兩者具極顯著正相關，其中有49種的分級僅差1級，而有131種（73%）藉此兩方法分類結果一致，顯示藉光合潛力來區分亞熱帶闊葉樹種的耐陰性，是合理且具有實用性。本研究已建立台灣原生闊葉樹種180種的耐陰性名錄，可供育林、生態復育及景觀植栽參考。

關鍵字

專家意見 ； 光環境 ； 耐陰性等級 ； 亞熱帶闊葉樹種 ； 光合潛力

並列摘要

Understanding the shade-tolerance ability of a species is crucial for the successful tending of young seedlings and selecting forestation species. Yet, no systematic investigations about the shade tolerance of native tree species have been carried out so far by foresters in Taiwan. In this study, we cultivated numerous seedlings of native broadleaf tree species in a nursery at National Pingtung University of Science and Technology. We measured the photosynthetic capacity (A_(max)) of 180 species during the rainy seasons of 2009~2014. The quantified data were applied as a physiological index for determining the shade-tolerance ability of a species and thereby classifying the species into 5 different shade-tolerance levels. To validate the suitability of this application, 6 experts of dendrology with years of field experience were asked to fill out a questionnaire for the tested species. The questionnaire inquired about the most likely light environment for natural recruits of each species. Then we compared the A_(max) results with the experts' opinions. Results showed that Amax of the 180 species ranged 35.8~9.1 μmol CO2 m-2 s-1; the first 5 species with the highest A_(max) values included ＂Hibiscus taiwanensis＂, ＂Melia azedarach＂, ＂Mallotus japonicas＂, ＂Hibiscus tiliaceus＂, and ＂Broussonetia papyrifera＂, while ＂Garcinia subelliptica＂ showed the lowest. With reference to the experts' opinions, we divided Amax into 5 levels: ≧ 26.0, 25.9~21.0, 20.9~15.0, 14.9~12.5, and ＜ 12.5 μmol CO_2 m^(-2) s^(-1), corresponding to shade-tolerance levels 1, 2, 3, 4, and 5 (namely very intolerant, intolerant, moderately tolerant, tolerant, and very tolerant). By the Amax classification, numbers of species belonging to levels 1 to 5 were 18, 37, 70, 33, and 22; while according to the experts' opinions, respective numbers were 21, 52, 63, 40, and 4. Few species were considered to be very tolerant by the experts. The 2 sets of results showed a significant positive relationship with a Pearson's correlation coefficient of 0.92. Out of the 180 species, 131 (73%) species were classified into the same level by the 2 methods, and 49 species showed only 1 rank difference. Thus, employing Amax to classify the shade tolerance of subtropical broadleaf tree species is objective and practical. With these physiological data, we have established a database of shade-tolerance levels of subtropical broadleaf tree species of Taiwan. It provides references for forestation, ecological restoration, and ornamental applications.

並列關鍵字

expert opinion ； light environment ； photosynthetic capacity ； shade-tolerance level ； subtropical broadleaf tree