台灣特有樹種台灣假黃楊、小芽新木薑子及台灣梭羅木的生長及光合作用對光量的反應

Growth and Photosynthetic Responses to Light of 3 Taiwan Endemic Tree Species, Liodendron formosanum, Neolitsea parvigemma, and Reevesia formosana

郭耀綸(Yau-Lun Kuo) ； 江璧合(Bi-Ho Chiang)

《台灣林業科學》 18卷1期 (2003/03) Pp. 55-66

https://doi.org/10.7075/TJFS.200303.0055

摘要

台灣假黃楊、小芽新木薑子及台灣梭羅木是台灣特有樹種，為瞭解此三種林木基礎生物學及生態學特性，本研究探討其生長及生理活性在不同光環境的反應，提供維護本土生物多樣性之基本資料。試驗方法為將各樹種盆栽苗分別培育在相對光量65、35及10%的人工遮蔭設施，以及森林孔隙和林下共5種環境。經17mo後收穫，發現台灣假黃楊在孔隙及林下生長不良，但在10、35及65%的光環境有很高的樹高及生物量相對生長率，孔隙苗木與較高光環境的苗木相比，形態可塑性極高。小芽新木薑子孔隙苗木有最大的樹高，其生物量也和較高光環境的苗木類似。台灣梭羅木以65%光環境的苗木有顯著最大的生物量，隨著光環境的改變可有很高的形態可塑性。在生理方面，台灣假黃楊與小芽新木薑子的光合作用光反應以孔隙苗木最高，台灣梭羅木則以65%光環境者最高。小芽新木薑子在孔隙的苗木有極低的暗呼吸率及光補償點，但光飽和光合作用率可高達11.5μmol m^(-2)s^(-1)。此現象極為特殊，顯示該苗木雖具蔭葉特性，卻有很高的光合作用潛力。綜上所述，台灣假黃楊不適宜在低光環境生長，對光的耐性範圍較窄；小芽新木薑子對光的耐性範圍廣，在孔隙環境有良好的生長及生理表現；台灣梭羅木適宜培育在較高光量，其形態及生理可塑性為此三樹種中最高者。

關鍵字

孔隙 ； 光環境 ； 光飽和光合作用率 ； 形態可塑性 ； 生理可塑性 ； 相對生長率

並列摘要

Liodendron formosanum, Neolitsea parvigemma, and Reevesia formosana are tree species endemic to Taiwan. In order to provide basic biological and ecological in formation for maintaining local biodiversity, we conducted a series of experiments to reveal the growth and photosynthetic responses of these species to different light conditions. We grew potted seedlings of each species in a forest understory, a forest gap, and in 3 artificial shade houses which provided 10, 35, and 65% full sun, respectively. Growth performances were poor for L. formosanum seedlings grown in the forest gap and understory after 17 mo of treatment. In contrast, relative growth rates in height and biomass were high for seedlings of this species grown in the 10, 35, and 65% light environments. Seedlings of L. formosanum grown in the gap environment showed higher morphological plasticity compared to those grown in higher light environments. Seedlings of N. parvigemma grown in the forest gap had the tallest height among all treatments. However, no significant difference was found in biomass between gap seedlings and seedlings grown in higher light environments. For R. formosana, seedlings grown in the 65% light environment had the highest biomass among all treatments. Growth performances of R. formosana seedlings varied significantly with growth light environment which indicates a high capability for morphological plasticity in this species. As for the physiological response, gap seedlings of L. formosanum and N. parvigemma had the highest photosynthetic rates at all light levels compared to those grown in other environments. But for R. formosana, seedlings grown inthe65% light environment had the highest photosynthetic rate among all treatments. Interestingly, seedlings of N. parvigemma grown in the gap had a very high light-saturated photosynthetic rate of 11.5 μmol m^(-2)s^(-1), but an extremely low dark respiration and light compensation point. These results indicate that gap seedlings of this species having shade-leaf characteristics with a high capacity for photosynthesis. In conclusion, seedlings of L. formosanum grew poorly under low-light environments and had a relatively narrow range of tolerance to growth light. Seedlings of N. parvigemma had a broad light-tolerant capability and responded well to gap conditions both morphologically and physiologically. Reevesia formosana seedlings grew well in high-light environments and had high plasticity in both morphology and physiology.

並列關鍵字

gap ； light environment ； light-saturated photosynthetic rate ； morphological plasticity ； physiological plasticity ； relative growth rate