Vertical Profiles of CO2 Concentration and δ^13C Values in a Subalpine Forest of Taiwan

台灣亞高山帶森林內二氧化碳濃度和穩定性碳同位素比值之探討

高文媛(Wen-Yuan Kao) ； 邱毓勛(Yu-Shiun Chiu) ； 陳婉華(Wan-Hwa Chen)

《Botanical Bulletin of Academia Sinica》 41卷3期 (2000/07) Pp. 213-218

https://doi.org/10.7016/BBAS.200007.0213

摘要

本文探討台灣一亞高山帶森林（位於多鸳鸯湖生態保留區）內二氧化碳濃度和其穩定性碳同位素比值(δ^13Cco2)之垂直變化；并比較森林內不同高度之維管束植物和一附生苔蘚植體之碳同位素比值(δ^13Cco(下標 leaf))。目的在了解此森林生態系內之碳通量，并提供建立全球碳循環模式之區域性基本資料。在1995年間，每個月測量森林內不同高度之二氧化碳濃度并分析其穩定性碳同位素比值。結果顯示：林內愈接近地面之空氣，CO2濃度愈高，同時其δ^13Cco2比值也愈負。每個月所測得的林內二氧化碳濃度倒數和其相對之δ^13Cco2比值呈現一顯著線性正相關；此線性正相關的截距具季節性變化，表示系統內呼吸作用有季節性變化。綜合1995年整年之測量，得到的線性正相關為：δ^13Cco2=5472.8×(1/[CO2])-23.5,r=0.95。採自林内不同高度維管束植物和苔藓之δ^13Cco(下標 leaf)也呈現和林內CO2之δ^13Cco2相同趨勢。此外，苔蘚植物之δ^13Cco(下標 leaf)值(-27.4到-29.2‰)較維管束植物之δ^13Cco(下標 leaf)值(-28.6到-33.5‰)為正。文中并討論影響苔蘚和維管束植物碳同位素比值差異之可能機制。

關鍵字

鴛鴦湖生態系 ； 亞高山帶森林 ； 二氧化碳 ； 穩定性碳同位素比值 ； 苔蘚

並列摘要

We investigated the vertical gradients in CO2 concentration and stable carbon isotope ratio (δ^13Cco2) of the canopy air within a coniferous-hardwood, Chamaecyparis and Rhododendron dominated, subalpine forest in Taiwan. The stable carbon isotope ratio of vascular plants and a epiphytic bryophyte species (Bazzania fauriana) (δ^13)C(subscript leaf)) from different heights within the forest were also analyzed. Results revealed that CO2 and δ^13Cco(subscript 2) gradients did exist within the forest, with higher CO2 concentrations and more negative δ^13Cco(subscript 2) values in air sampled from the lower canopy. The average vertical gradients in CO2 and δ^13Cco(subscript 2) value of the CO2 of the 12 sampling dates were 28.5±6.1ppm and 1.3±0.3‰, respectively. Seasonal patterns of the relationship between l/[CO2] and the corresponding δ^13C were pronounced, with steady decreases in the slopes and increases in the intercepts found from January to August. A decreasing δ^13C(subscript leaf) with decreasing height was also measured in a bryophyte (ranging from-27.4 to -29.2%o), canopy and understory leaves (ranging from -28.6 to -33.5%o). It was estimated that photosynthetic physiology affected by microclimates within the forest contributed approximately 2.8% of variation of the vertical gradient of vascular plant δ^13C values.

並列關鍵字

Bryophyte ； CO2 Subalpine forest ； Stable carbon isotope ratio.