• 作者： 吳俊宗; 莊佩佩; 吳麗容; 陳鎮東
• 作者服務機構： 中央研究院植物研究所; 台灣大學植物系; 中山大學海洋地質系
• 中文摘要： 　　本文以湖積物中之矽藻為指標，研究大鬼湖東北小湖之酸鹼性、營養態、腐水級等在近千年來之變遷情形。大鬼湖海拔2,150公尺，其周圍為原始森林，從湖中所挖掘50公分長之湖積物中，其矽藻相以三種方法所推算之酸鹼度值均為弱鹼性，而與現在湖水之酸鹼度值相近。現在湖水之營養態介於貧養和中養之問，此也與由湖積矽藻推算所得相近。酸鹼度值在近千年來甚少變化，惟於近百餘年來有酸鹼度值略降低之現象，此時並同時有總碳和總氮量的增高，以及腐水級及營養態略微下降的現象。從結果顯示，此種酸鹼度值降低之現象，與國外所發現之百餘年來環境酸化之現象相似，推測此係與大氣污染物流入有關，而非土地利用或林相改變所造成。本文應用由鴛鴦湖資料所導出之模式於此湖泊，發現可以適用，結果並顯示，矽藻是研究湖泊環境變遷的良好指標。
• 英文摘要： Diatom assemblages in the sediments of a tropical alpine lake, Great Ghost Lake, were used in thepresent study as indicators of palaeo-environmental changes. At an altitude of 2,150 m, Great Ghost Lake islocated in southern Taiwan within an undisturbed natural alpine forest. It is an oligotrophic and slightlyalkaline lake. A sediment core, 50 cm long, was taken from the middle of the lake and used for the presentstudy. Diatom assemblages in the sediments were used to infer the pH, total phosphorus, trophic state, andsaprobity of the palaeo-environment. The diatom-inferred values matched well with the measured variablesof present lakewater. The inferred pH values had retained a slight alkalinity over the last thousand years. Achange in pH toward acidic values had occurred during the last century. The decrease in pH was associatedwith a decrease in the saprobity and trophic state index values, and with enhancement of the amounts oftotal C and total N in the sediments. It is assumed that the decrease of pH was related to increased depositionof atmospheric pollutants rather than to land-use and vegetation changes. The results of the present studyshow that the regression model derived from Yuenyang Lake is applicable to this lake and suggest that dia-toms are a good bioindicator for study of palaeo-environmental changes.
• 中文關鍵字： acidification; diatom assmblage; Great Ghost Lake; lake sediment; palaeolimonology; pH indicator; trophic state.
• 英文關鍵字： --