以生態棲位寬度評估台灣水韭在陽明山夢幻湖濕地適合生長之水深

Using Niche Breadth Measurement to Evaluate the Profitable Water Depth for Isoetes Taiwanensis in Dream Lake, Yangmingshan National Park

陳寧庸(Neng-Iong Chan) ； 張文亮(Wen-Lian Chang)

《農業工程學報》 56卷3期 (2010/09) Pp. 32-42

https://doi.org/10.29974/JTAE.201009.0003

摘要

台灣水韭（Isoetes taiwanensis DeVol）生長在陽明山夢幻湖濕地，海拔866 m，由於長期水位的不穩定與缺水，造成陸生植物的入侵。本研究自2008年7月分後發現，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，並且發現若連續乾旱超過20天，台灣水韭的繁殖率就會下降。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r^2值為0.684；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49 cm左右，水量為410 m^3；維持台灣水韭族群數量得以存活的水深為24.79 cm，水量為213 m^3，使台灣水韭族群面臨可能消失的平均水深為4.15 cm，水量為1.56 m^3。

關鍵字

台灣水韭 ； 競爭 ； 水量 ； 水深 ； 生態棲位寬度

並列摘要

Isoetes taiwanensis grows in the Dream Lake wetland, Yangmingshan National Park, Taiwan. Because of water shortage and fluctuation of water table, resulted in the terrestrial macrophytes invation. 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. We also found that the reproductive rate of I. taiwanensis would decrease while the dry period is more than 20 days. So, it is very important to maintain certain amount of water in its critical period. The competitors with I. taiwanensis are Eleocharis congesta, Sphaerocaryum malaccense, Schoenoplectus mucronatus, Sphagnum palustre and Eleocaris dulcis. From the B' value of July and 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 could reveal from its population abundance after one month of the disturbance, and its correlation with reproductive rate (r^2) was 0.684. 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 49 cm, I. taiwanensis would have greater potential in competition among most of the species over water depth, and its water quantity is 410 m^3. While water depth was 24.79 cm, water quantity is 213 m^3 could it maintain the population size of I. taiwanensis. 4.15 cm of water depth with 1.56 m^3 water quantity would probably cause I. taiwanensis distinction.

並列關鍵字

Isoetes taiwanensis ； Competition ； Water quantity ； Water depth ； Niche breadth