| 摘要: | 摘要 河川棲地型態分佈對於河川生態優劣甚為重要，而河川流量則是影響河川棲地分佈的重要指標之一。本研究以流速、水深兩水理參數對棲地進行分類，並考量魚類克服流速與水深的條件，以碎形維度與FRAGSTAT計算景觀生態指數探討河川棲地分佈特性，以烏溪中上游河道為研究樣區，模擬流量在2CMS-400CMS間棲地的變化情形。結果顯示小嵌塊體維度值差異極大，隨面積增加維度值趨於定值，介於1.5-1.6間。深潭維度值為最高表其具複雜邊界。以整體河川棲地而言，棲地面積、平均嵌塊體面積、嵌塊體總邊長、面積標準差與流量呈正相關。平均碎形維度、面積權重平均碎形維度值顯示棲地趨於規則。隨流量增加淺瀨、淺流面積不減小（棲地不消失），當流量為6CMS時，淺瀨面積有最大值，而淺流面積也達最大值的80％左右，故流量為6CMS時即可達到極佳的棲地效益，此時流量為Q95。個別潭瀨棲地上，平均嵌塊體面積以深流最大深潭為最小。形狀指數可知淺流的嵌塊體最偏離正方形，深潭較趨近於正方形。深潭與淺瀨具較高的平均嵌塊體分維數，表具有較複雜的邊緣。當流量為14cms時歧異度有最高值為0.77。 ABSTRACT The distribution of river habitant is important to the river ecological system, and the discharge is considered to be one of the most important indices to influence that. In this study, flow velocity and water depth are selected to classify river habitant pattern. Moreover, the fractal theory and landscape ecological indices, which are calculated by FRAGSTATS, are used to investigate the properties of distributions. The Wu-Chi river is selected as the study site, and the simulated discharges are focused on 2 CMS to 400 CMS. Comparative results demonstrated that the fractal dimension is discrepancy among small patches. However, the fractal dimension achieves to a constant (1.5-1.6) as increasing areas. In this case, the values of Total (Class) Area, Mean Patch Size, Total Edge, and Patch Size Standard Deviation all are directly proportion to the river flow, and the Mean Patch Fractal Dimension is between 1.02 and 1.18, and Area-Weighted Mean Patch Fractal Dimension is between 1.10-1.24. The study found that the area of riffle is the maximum as the discharge is about 6 CMS (Q95). Moreover, the area of glide in the case of 6 CMS is also reaching the 80% of maximum total area of glide in all cases. In the average area of habitant, run is the biggest ,and pool is the smallest. In shape index, pool is the most closed to a square, but glide revealed discrepancy in a square. Pool and glide have the high values of area weighted mean patch fractal dimension which shows that the edge is more complex. The highest value of Shannon Diversity Index is 0.77 at 14CMS. |
