三種附生蕨類個體大小與生理生態的關係

Abstract

植物的生理生態可反應生長、健康和繁殖等狀況，常用以探討植物如何應對環境變化。然而，先前的研究中，常忽略植物個體體型大小與生理生態之間的關係，這可能影響了種間生理差異的比較結果。本研究在臺灣東北部的福山試驗林對三種常見的附生蕨類：巢蕨 (Asplenium antiquum Makino)、垂葉書帶蕨 (Haplopteris zosterifolia Willd.) 和腎蕨 (Nephrolepis auriculata (L.) Trimen) 探討以下二個問題：(1) 三種附生蕨類物種體型差異和生理生態，包含光合作用速率、蒸散速率、氣孔導度、葉內二氧化碳濃度 (Ci) 、氣孔大小、氣孔密度、葉綠素濃度和葉綠素a/b之間的關係為何？(2) 個體體型大小與生理生態的關係在三個物種間是否一致？研究結果發現，巢蕨和腎蕨體型大小與光合作用速率、蒸散速率、氣孔導度和氣孔大小有負向關係的趨勢，垂葉書帶蕨體型大小則與這些生理生態參數有正向的關係。三物種氣孔密度與氣孔大小皆呈現負向關係。巢蕨個體大小與葉綠素濃度呈顯著正向關係，腎蕨個體大小與葉綠素濃度為顯著負向關係，在垂葉書帶蕨這些關係則不顯著。體型大小和 Ci 的闗係在三者皆不顯著。總結來說，體型大小和生理生態的關係在三物種間不具一致性，這顯示在進行物種間生理生態比較時需考量體型大小可能的影響。將本研究的巢蕨和前人對另外二種同屬 (鐵角蕨屬) 附生植物的研究結果相比，也發現個體大小與生理生態的關係在三個物種間亦無一致的趨勢，這顯示親緣關係應非主導體型大小和生理生態之間闗係最重要的因子。本研究為觀察性研究雖指出體型大小對生理生態的影響在不同附生植物間無一致的現象，但尚無法明確指出其影響的機制，仍需更多研究加以釐清。Because plant ecophysiology can reflect plant growth, health, and reproduction condition, it is often used to explore how plants adapt to environmental changes. However, previous studies have often overlooked the relationship between plant size and ecophysiology, which may have influenced the results in comparing physiological differences between species. This study, conducted in the Fushan Experimental Forest in northern Taiwan, investigated three common epiphytic fern species—Asplenium antiquum Makino, Haplopteris zosterifolia Willd., and Nephrolepis auriculata (L.) Trimen. The study aimed to address the following two questions: (1) Does the size difference of the epiphytic fern species significantly affect their ecophysiological traits, including photosynthetic rate, transpiration rate, stomatal conductance, and internal CO2 concentration (Ci), stomatal size, stomatal density, chlorophyll concentration, and chlorophyll a/b ratio? (2) Are the relationships between size and ecophysiological traits consistent across the three species? The study found that for A. antiquum and N. auriculata, plant size was negatively related to photosynthetic rate, transpiration rate, stomatal conductance, and stomatal size, whereas H. zosterifolia exhibited the opposite trend. The stomatal density was negatively related to stomatal size across the three species. Regarding the relationship between plant size and chlorophyll concentration as well as chlorophyll a/b ratio, A. antiquum showed a significant positive relationship with plant size and chlorophyll concentration, while N. auriculata showed a significant negative relationship, and H. zosterifolia showed no significant relationship. No significant relationship between body size and internal CO2 concentration (Ci) was found in any of the three species. In summary, the results of the ecophysiology traits were not consistent across the three species. Comparing the result of this study with two previous studies on two Aspleniun species, it is found that even among the three closely related Asplenium species, plant size influenced their ecophysiological traits differently. This suggests that phylogenetic relationships do not play a dominant role in determining the relationship between plant size and ecophysiology. Although this observational study points to the lack of consistency in the effect of plant size on ecophysiology among different epiphytic plants, the underlying mechanisms remain unclear and deserves further investigations.