攔沙壩水棲昆蟲功能攝食群群聚結構連續變化

Abstract

本研究於台北縣烏來鄉桶后溪中游最上游之攔砂壩上下各100公尺內分別設置三個樣點，分析各樣點之環境參數、功能攝食群 (Functional feeding groups) 群聚組成與粗細有機顆粒比值之相關性，以探討出攔砂壩對各功能群結構的影響。單變數分析結果顯示攔砂壩上游遮蔽度受壩體影響範圍較廣，其餘環境參數在壩體上下游50m間差異較明顯；粗細顆粒有機碎屑比值與環境因子單調化程度，依河序縱向變化呈現的不連續現象，與大型水壩對河川造成的干擾相似。單變數分析各功能攝食群豐度百分比則以聚集與過濾採食者受攔砂壩影響較顯著；群聚結構也有受攔砂壩影響。多變數分析結果顯示功能攝食群豐度百分比組成與群聚結構差異集中在壩體正上方50公尺以內的樣站。In order to understand the effects of check dams on the transportation of organic matters and functional compositions of aquatic insects, six sampling sites were selected around the most upstream dam in the Tong-Hou Stream. Environmental variables and aquatic insects were sampled in February, March, May and July 2008, and the habitat characters of each site were recorded as well. This study showed that stream width, depth, discharge and canopy carried out a significantly differed between upstream and downstream of check dam. The coarse and fine particulate organic matter ratio, the ratio of abundances of gathering- and filtering- collectors was presented a significantly differed between two sites just above and under the check dam. Furthermore, the community structure of FFG have distributed with discontinuous patterns just above the check dam. Although the disturbed ranges only focus in 50 meter scopes of the check dam, the discontinuity results were still in accordance with dams.