水分與營養限制對附生植物臺灣巢蕨(Asplenium nidus)生長影響之探討

Abstract

水及營養是影響生態系初級生產力的重要因子，然而氣候變遷直接或間接改變了生態系中諸多環境因子包括水及營養元素的可利用性，使植物生長甚至存活受到重大影響。附生植物所需資源大多直接來自大氣中，對於氣候的變化可能更為敏感，有研究指出其營養限制與該生態系的地生植物相似，且生長週期較地生植物尤其樹木短，對於施肥實驗有更快的反應，故可用施肥實驗探究其營養限制，進而推論生態系營養限制。本研究欲探討水及營養對附生植物生長的限制，透過採集福山植物園及烏來福山村的臺灣巢蕨(Asplenium nidus Linn.)，於溫室內進行為期一年限制水分(高、低水組)及施肥實驗(加氮、加磷、加磷氮、控制組)。發現臺灣巢蕨的葉面積在高水組顯著高於低水組，施氮磷肥組則在不同水處理皆為最高，施氮組及施磷組分別在高低水處理中呈現相反的結果；葉內元素分析結果，大多在高水組有較高含量，少數元素如碳與鉀在低水組反而較高。結果顯示臺灣巢蕨的生長受到的水分限制影響比營養限制更大，並且可能受到氮磷的共同限制。

Water and nutrition are important factors influencing the primary productivity of ecosystems. Climate change has directly or indirectly changed many environmental factors, including water and nutrient availability, which has greatly affected the growth and even the survival of plants. Most epiphytes absorb nutrition and water directly from the atmosphere so they are likely more sensitive to climate change. Studies suggested that the nutrient limitation of epiphytes is similar to non-epiphytes of the ecosystem. Moreover, epiphytes have much shorter life spans than non-epiphytes, especially trees. Thus, fertilization experiments can be used to examine epiphyte nutrient limitation and infer ecosystem nutrient limitation. This study aims to examine how the response of epiphyte growth to water and nutrition manipulation. We collected Taiwan nest fern (Asplenium nidus Linn.) from Fushan Botanical Garden and Wulai Fushan Village, then manipulated their water availability (high and low) and nutrient availability (adding nitrogen , phosphorus, phosphorus plus nitrogen, control) in the greenhouse. It was found that the leaf area of A. nidus in the high water group was significantly greater than low water group. Among the different fertilization groups the nitrogen plus phosphorus fertilization group was the highest across different water treatments. Nitrogen addition and phosphorus addition showed opposite effects on A. nidus growth between high and low water treatments. Leaf elements content was overall higher in the high water group, but a few elements such as carbon and potassium were higher in the low water group. The results showed that the growth of A. nidus was more affected by water limitation than nutrient limitation and may be co-limited by nitrogen and phosphorus.