- 期刊
- OpenAccess
夢幻湖之臺灣水韭休眠球莖分布及活力
Distribution and Viability of Dormant Corms of Isoetes taiwanensis DeVol in Menghuan Pond, Taipei, Taiwan
摘要
夢幻湖臺灣水韭族群隨著水位變化呈現季節性消長現象，前人研究報告指出，當夢幻湖從豐水期轉為低水期，臺灣水韭將因其它伴生植物競爭及不耐乾旱而被淘汰；當雨季水位回升時，透過土壤中臺灣水韭孢子有性生殖補充族群株數。我們推測夢幻湖土壤中臺灣水韭休眠球莖對恢復族群植株亦具有關鍵性影響力。為證明此一假設，我們蒐集夢幻湖6個樣區土樣並計算臺灣水韭休眠球莖數量及檢測其活力。結果顯示6個樣區中，在靠湖岸的樣區，因伴生植物長葉雀稗之優勢生長，未見有臺灣水韭之生長，亦未見其休眠球莖；其餘5個樣區土樣中具有密度2.7－14.0顆/L的臺灣水韭休眠球莖，當中74.8%（80/107）具有活力，在浸水2週內長出新葉。本研究支持假設：夢幻湖內臺灣水韭在低水期葉片枯萎，以休眠球莖方式續存；當雨季水位回升之際，休眠球莖重新長葉及根，其族群個體將可得到補充。
並列摘要
The population of Isoetes taiwanensis DeVol in Menghuan Pond, Yangminshan National Park, Taipei, Taiwan, fluctuates seasonally with changes in water level. Previous studies indicate that I. taiwanensis individuals intolerant of drought would be eliminated by the competition of other plants during dry season, but the population would recover as spores from sexual reproduction germinate when water level rose during rainy season. In addition to this supplement of spores, we speculate that the dormant corms of I. taiwanensis in the soil also have a relevant influence on population recovery. To confirm this hypothesis, we collected soil samples from six plots, and measured the number and vitality of dormant corms of I. taiwanensis therein. The results show that soil sampled from the lakeside had no plant and corm of I. taiwanensis, which may be caused by the dense growth of Paspalum longifolium. The other five plots contained dormant corms, with density varying from 2.7 to 14.0 corms / L. Vital dormant-corms generated new leaves after two weeks of soaking. The total regeneration rate was 74.8% (80/107). This study supports our hypothesis that leaves of I. taiwanensis in Menghuan Pond would wither during the period of low water level, but individuals survive by dormant corms. The population would recover when those dormant corms produce new roots and leaves as water level rises in the rainy season.