大肚溪口1990至2014年的鳥類群集變遷

Abstract

大肚溪口自1990年代起經歷台中火力發電廠興建、彰濱工業區開發等大型工程，為了瞭解工程是否影響地景進而導致鳥類群集改變，本研究使用1990至2014年大地衛星 (Landsat) 影像，探討大肚溪口自1990年後的地景變遷對鳥類群集的影響。研究樣區包含彰濱區、南岸區、電廠區、張玉姑廟區，將樣區範圍的衛星影像以混合監督式與非監督式分類 (Hybrid supervised and unsupervised classification)，分析各地景面積變化。以種豐度、量豐度、Jaccard相似度指數、Simpson均勻度指數了解水鳥群集的結構變化，並以簡單線性迴歸計算泥灘涉禽、水域泥岸游涉禽、水岸高草游涉禽三類水鳥同功群每季種豐度與平均量豐度的長期趨勢。最終依本研究分析結果探討大肚溪口的地景變遷、鳥類群集與長期趨勢之關係。結果顯示，大肚溪口整體同功群水鳥種豐度與平均量豐度下降，且彰濱區下降的最明顯，本研究推測是與大肚溪口整體灘地面積下降、魚塭面積下降、建地面積上升等地景變遷有關。而水鳥的Jaccard相似度指數、Simpson均勻度指數逐漸上升，代表水鳥組成越來越相似且量豐度集中在少數鳥種；2000年後，大肚溪口整體干擾趨向緩和，部分水鳥雖然量豐度有逐漸回升，但主要集中在少數優勢種鳥種如東方環頸鴴 (Charadrius alexandrines)、黑腹濱鷸 (Calidris alpine)、大白鷺 (Ardea alba)、蒼鷺 (Ardea cinerea)、黃頭鷺 (Bubulcus ibis) 等；而雁鴨科、IBA鳥種黑嘴鷗 (Chroicocephalus saundersi) 呈現下降趨勢。至2014年為止，南岸區為水鳥種豐度、量豐度最多的樣區；而張玉姑廟區轉為較適合陸鳥生存的地區。環境管理上建議控制大肚溪口的野狗數量；南岸區魚塭可利用分批曬池、清除堤岸上的雜草使能見度提高，有助於增加水鳥漲潮時的停棲地。

Since the 1990s, Da-du Estuary has experienced large-scale projects such as the construction of Taichung Power Plant and Changhua Coastal Industrial Park. In order to understand whether the projects affect the landscape, thus leading to changes in waterbird assemblages, this study used Landsat satellite images from 1990 to 2014 to explore the effects of landscape changes on waterbird assemblages in Da-du Estuary. Da-du Estuary was divided into Changhua Coastal Industrial Park, South Coast Zone, Taichung Power Plant and Chang Yu-Ku Temple. Hybrid classification (a combination of supervised and unsupervised classification) was applied to a series of Landsat images to explore each landscape area changes in the four zones. We used species richness, average abundance, Jaccard similarity index and Simpson evenness index to examine the changes on waterbird assemblages structure. Then, we focused on three waterbird guilds, which were shore-mudflat, water-shore, and water-shore-highgrass, and used simple linear regression to understand the long-term trend of each season in each guild. Finally, we compared the relationship between landscape changes, waterbird assemblages and long-term trends of waterbirds.The results showed that the species richness and abundance of the whole waterbird guilds decreased, and the decline in the Changhua Coastal Industrial Park was the most obvious. We speculates that it is related to the total mudflat area decreased, the area of aquaculture ponds decreased, and the building area increased. The Jaccard similarity index and Simpson evenness index of waterbirds increase during the years, which means that the waterbird assemblages is more and more similar and the abundance is concentrated on a few bird. After 2000, the overall disturbance of Da-du Estuary decreased, although some of the waterbird guilds have gradually increased their abundance, they are mainly concentrated on a few dominant species such as Kentish Plover (Charadrius alexandrines), Dunlin (Calidris alpine), Great Egret (Ardea alba), Gray Heron (Ardea cinerea), Cattle Egret (Bubulcus ibis), etc., while Anatidae, and Saunders’s Gull (Chroicocephalus saundersi) showed a negative trend. As of 2014, the South Coast Zone is the most species richness and abundance of waterbirds. Chang Yu-Ku Temple has truned into a region more suitable for landbirds. In the environmental management, we recommend controlling the number of roaming dogs in the Da-du Estuary. The aquaculture ponds in the South Coast Zone can take turn to dry pool and clear weeds on the the bunds to improve the visibility, and helps increase the roost of the waterbird during high tide period.