環境因子和人為干擾對夢幻湖溼地台灣水韭的影響

瀕危水生植物台灣水韭(Isoetes taiwanensis DeVol) 於西元1971年在其唯一自然棲地陽明山夢幻湖溼地被發現，並在同一水域中與其他陸生植物及挺水植物做生長競爭。西元2006年在時調查夢幻湖台灣水韭時，因僅發現七株台灣水韭而被視為瀕危物種。於是荒野保護協會在西元2008年進行台灣水韭原棲地保護計畫，將夢幻湖溼地做邊坡護岸處理、溼地底部夯實處理。此計畫使得台灣水韭在夢幻湖溼地的個體量有逐漸增加的趨勢，然而對於台灣水韭生存的關鍵因素尚未有瞭解，故本研究想探討台灣水韭的生態棲位特性及需求。本研究從2009年5月到2010年12月在夢幻湖溼地逐月監測24個樣區，每月記錄樣區裡的物種覆蓋率及水深、水溫、土溫。研究結果發現，環境因子影響台灣水韭覆蓋率的主因為水文。台灣水韭在夢幻湖溼地裡最適生長年平均水深為50公分，年平均水深30公分以下無台灣水韭的蹤跡，年平均水深60公分時，台灣水韭的覆蓋率高達90％。而棲地內與台灣水韭有競爭關係的物種為針藺、荸薺、水毛花，台灣水韭生長最具競爭優勢是在年平均水深48.6~185.6公分。除此之外，為了降低其他物種與台灣水韭的生存競爭，本研究發現人為夯實確實有助於提高水位，而水位上升能抑制稃藎的生長。同時，人為移除強勢物種也可抑制水毛花在夢幻湖溼地的蔓延，並建議至少每隔八年要移除荸薺。最後，根據本研究的結果在保育台灣水韭時，調控水文及移除強勢種的措施上有所依據。

關鍵字

水位管理；水深；台灣水韭；復育；溼地

並列摘要

Isoetes taiwanensis DeVol, was discovered in 1971, is a critically endangered aquatic plant endemic to Taiwan. The only natural habitat of I. taiwanensis is the Menghuan Pond wetland in northern Taiwan. With competition of some aquatic plants and terrestrial plants, I. taiwanensis was close to extinction in 2006. The bottom of the Menghuan Pond wetland was compacted and fractures were filled along the shore to improve the average water depth in 2008. The I. taiwanensis population was restored, but factors which is crucial to its survival remain unclear. To analyze the factors, we monitored 24 plots in the Menghuan Pond wetland monthly from May 2009 to December 2010 to record the coverage rates of potential competitive plant species and hydrology data. The wetland was found to be an ideal environment for growth of I. taiwanensis with annual mean water depth 50 cm. The species did not grow in plots with annual mean water depth lower than 30 cm. With the deepest annual mean water level, > 60 cm, more than 90％ of the area was covered. The species had an advantage over other species in plots with annual mean water depth 46.8 to 185.6 cm. The coverage rate of I. taiwanensis was positively associated with annual mean water depth. Fluctuation of the water level may reduce the competition among I. taiwanensis and other species, particularly Eleocharis congesta, Eleocharis dulcis, and Schoenoplectus mucronatus. These data may help in designing a protocol for sustaining conservation of I. taiwanensis in Yangmingshan National Park.

並列關鍵字

Conservation ； Isoetes taiwanensis ； Water depth ； Water management ； Wetland

參考文獻

陳寧庸，民國98年，陽明山夢幻湖台灣水韭棲地的生態復育，國立台灣大學生物環境系統工程學研究所碩士論文。

張永達(2001)台灣水韭的生態與保育。科學教育月刊 240:44-47

Huang SF, Chiang SHT (1986) The development of the female gametophyte in Isoetes taiwanensis DeVol. Taiwania 31:15-32

DeVol CE (1972 b) A correction for Isoetes taiwanensis DeVol. Taiwania 17:304-5

DeVol CE (1972 a) Isoetes found on Taiwan. Taiwania 17:1-7

國際替代計量

環境因子和人為干擾對夢幻湖溼地台灣水韭的影響

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