台灣鹽田植群之研究

Vegetation of the Salterns in Taiwan

台灣原有六個鹽場，總面積達六千餘公頃，惟歷經逐步裁廢，目前僅剩布袋、北門及七股三個鹽場，廢曬鹽田約有二千公頃，有些已自然演替為鹽生草澤或紅樹林。本研究就廢曬鹽田生育地土壤與積水性質、水位、以及植群分布、季節消長與演替加以探討，以供廢鹽田綠化之參考。鹽田積水之鹽分受海水引入、降水及蒸發等因素之影響，每年10月至翌年4月間引入海水曬鹽，鹽分較高，電導度可達60.9 mS/cm；5~9月為雨季，鹽分略被稀釋。鹽田土壤pH值多在8以上。土壤鹽分偏高，尤以結晶池更高，電導度可高達63.9 mS/cm。鹽場之維管束植物共調查到32科106種。實際曬鹽之處，鹽分偏高，僅出現13科24種鹽生植物，主要為濱水菜及鹽地鼠尾粟，其次為鹽定及海雀稗，局部有欖李及海茄冬入侵。植群覆蓋度主要隨水位變動與季節變化而消長，鹽定及海雀稗受水位影響尤大。植群之入侵廢曬鹽田，先從鹽分濃度較低之土堤開始，再往兩側侵入蒸發池內。濱水菜為先驅植物，之後鹽地鼠尾粟、鹽定、海雀稗，以及紅樹林欖李、海茄冬等逐漸入侵，接著為蘆葦、水燭、冬青菊、田菁、水丁香、臭根子草、白茅、白花鬼針等一般草本，之後為馬纓丹、銀合歡等灌木與小喬木，最後由黃槿、構樹、血桐等一般喬木取代。 There were six salterns in Taiwan. Up to now, only three salterns are still under operation, and about 2,000 hectares have been abandoned. Abandoned salt pans have naturally succeeded to salt marshes or mangroves. Soil and water properties, water level, plant distribution and succession at salt pans were studied. The water salinity was affected by seawater input, rainfall and evaporation. From October to April, seawater was introduced for salt production, and electrical conductivity could reach 60.9 mS/cm. In rainy season, the brine was somewhat diluted. The pH of salt pan soils was mostly above 8. Soil salinity was particularly high at crystallizing ponds, and electrical conductivity could reach 63.9 mS/cm. The vascular plants at the saltem sites include 106 species belonging to 32 families. There are only 24 species of halophytes at the salt pans under operation where soil and water salinity are extremely high. The dominant species are Sesuvium portulacastrum, Sporobolus virginicus, uaeda maritime, Paspalum vaginatum, Lumnitzera racemosa and Avicennia marina. Plant cover was affected by water level and seasonal changes. The cover of Suaeda maritime and Paspalum caginatum were significantly affected by water level. Generally, plants firstly established at the soil banks, and then invaded the concentrating ponds. Sesuvium portulacastrum was the pioneer, then followed by other halophytes such as Sporobolus virgiuicus, Suaeda maritime, Paspalum vaginatum, Lumnitzera racemosa, and Avicennia marina, and then Phragmites communis, Typha orientalis, Pluchea indica, Sesbania cannabiana, Ludwigia octovalvis, Bothriochloa intermedia, Imperata cylindrica var. major and Bidens pilosa. Then non-halophytic shrubs and small trees such as Lantana camara, Leucaena leucocephala invaded. Finally non-halophytic trees such as Hibiscus tiliaceus, Broussonetia papyrifera and Macaranga tanarius established.

There were six salterns in Taiwan. Up to now, only three salterns are still under operation, and about 2,000 hectares have been abandoned. Abandoned salt pans have naturally succeeded to salt marshes or mangroves. Soil and water properties, water level, plant distribution and succession at salt pans were studied. The water salinity was affected by seawater input, rainfall and evaporation. From October to April, seawater was introduced for salt production, and electrical conductivity could reach 60.9 mS/cm. In rainy season, the brine was somewhat diluted. The pH of salt pan soils was mostly above 8. Soil salinity was particularly high at crystallizing ponds, and electrical conductivity could reach 63.9 mS/cm. The vascular plants at the saltem sites include 106 species belonging to 32 families. There are only 24 species of halophytes at the salt pans under operation where soil and water salinity are extremely high. The dominant species are Sesuvium portulacastrum, Sporobolus virginicus, uaeda maritime, Paspalum vaginatum, Lumnitzera racemosa and Avicennia marina. Plant cover was affected by water level and seasonal changes. The cover of Suaeda maritime and Paspalum caginatum were significantly affected by water level. Generally, plants firstly established at the soil banks, and then invaded the concentrating ponds. Sesuvium portulacastrum was the pioneer, then followed by other halophytes such as Sporobolus virgiuicus, Suaeda maritime, Paspalum vaginatum, Lumnitzera racemosa, and Avicennia marina, and then Phragmites communis, Typha orientalis, Pluchea indica, Sesbania cannabiana, Ludwigia octovalvis, Bothriochloa intermedia, Imperata cylindrica var. major and Bidens pilosa. Then non-halophytic shrubs and small trees such as Lantana camara, Leucaena leucocephala invaded. Finally non-halophytic trees such as Hibiscus tiliaceus, Broussonetia papyrifera and Macaranga tanarius established.