陽明山夢幻湖台灣水韭棲地的生態復育

The restoration for the habitat of Isoetes Taiwanensis in Dream Lake,Yangmingshan National Park

陳寧庸(Neng-Iong Chan)

指導教授 ： 張文亮

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.01005

摘要

台灣水韭 (Isoetes taiwanensis DeVol)是全世界分佈緯度最低的水韭，陽明山夢幻湖是台灣水韭唯一的棲地，海拔866公尺的夢幻湖屬於泥碳型濕地 (bog)，湖底床的泥碳土 (peat soil) 有機質含量為4%，水質為酸性寡養，pH值在3.83到5.11之間，2008年的6月分到次年4月分多吹東北季風，2008年9月分到次年2月分的降雨量有3190 mm，湖區最大蓄水量為538 m3。夢幻湖雖然有豐富的雨水補助，但因為入滲與漏水嚴重，使得湖區在夏季時 (7月分)幾乎全乾，94 m的穿越線上平均水深只有1.83 cm。
從2008年7月分之後，台灣水韭對於水深的競爭力 (B’ 值) 相較於其他植物有下降的趨勢，直到2008年12月分才回復到對水深有競爭的優勢，這是因為乾旱有助於陸生與挺水性植物的生長與繁殖，而台灣水韭是一種沉水性植物，若連續乾旱超過20天，它的繁殖率就會受影響。故要在夢幻湖特定的時間裏維持特定的水量是相當重要的。
與台灣水韭競爭的物種有針藺、稃藎、水毛花、狹葉泥碳苔與荸薺。在2008年的7月與12月，2009年的2月與3月，從B’值來看，台灣水韭對於水深較其伴生植物具有較優勢的競爭力，並發現台灣水韭對水深的競爭能力約在受到水位的擾動一個月後，從族群的數量上表現出來，對於繁殖率的相關性係數r2值為0.577；而11月、1月與2月的水深分別為42.5 cm、50.8 cm與53.8 cm。然而台灣水韭與挺水性植物對水深的競爭至少水深達48.5 cm方具優勢性。使台灣水韭族群具水深的競爭性，水深需維持在56 cm左右，水量為312m3；維持台灣水韭族群數量得以存活的水深為24.79 cm，水量為213m3，使台灣水韭族群面臨可能消失的平均水深為4.15cm，水量為1.56 m3。

關鍵字

台灣水韭 ； 棲地 ； 生態復育 ； 競爭 ； 水量 ； 水深 ； 生態棲位寬度

並列摘要

Isoetes taiwanensis DeVol exist in the lowest latitude among the isoetes in the world, and the Dream Lake of Yangmingshan National Park, Taiwan, is its only habitat which located in the altitude about 866 m. Dream Lake is a bog and its peat soil contains 4% organic matter. The water is acidic and oligotrophic. pH is between 3.83-4.88. The northeastern monsoon was strongly affected in this area from June to April in 2008. It brought about 3190 mm precipitation during September to February in 2008. The maximum quantity of water reserve achieves 538 m3 in Dream Lake. Though the water subsidy from precipitation is very high, the infiltration and leaking are also high in the habitat, which was nearly dry in July 2008 (1.83cm, mean water depth from 94 m transect).
After July, 2008, compare to other plant species in the lake, the competition for water depth of I. taiwanensis (B’ value) became lighter, and it recovered until December, 2008. This is because the dry period is beneficial for the growth and production of terrestrial species and emergent species. I. taiwanensis is an submerged plant which reproductive rate would decrease while the dry period is more than 20 days.
The competitors with I. taiwanensis are Eleocharis congesta, Sphaerocaryum malaccense, Schoenoplectus mucronatus, Sphagnum palustre and Eleocaris dulcis. From the B’ value of July, December in 2008, February and March in 2009, I. taiwanensis have greater potential in competition among most of the species over water depth. It was found that the competence of I. taiwanensis can reveal from its population abundance after one month of the disturbance, and its correlation with reproductive rate ( r2) was 0.577. Furthermore, the water depth of November, 2008, January and February, 2009, were 42.5 cm, 50.8 cm and 53.8 cm. However, no less than 48.5 cm would I. taiwanensis compete against emergent macrophytes. In conclusion, when water depth was over 56 cm, I. taiwanensis would have greater potential in competition among most of the species over water depth, and its water quantity is 312m3. While water depth was 24.79 cm, water quantity is 213 m3 could it maintain the population size of I. taiwanensis. The distinction water depth was 4.15 cm with 1.56 m3 water quantity.

並列關鍵字

Isoetes taiwanensis ； habitat ； ecological restoration ； competition ； water quantity ； water depth ； niche breadth

參考文獻

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