蘭陽溪口地景變化對水鳥群集組成的影響

Landscape change on waterbird assemblages in Lanyang River Estuary

趙偉凱(Wei-Kai Chao)

指導教授 ： 李培芬

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2019年)

https://doi.org/10.6342/NTU201903854

摘要

濕地不但擁有豐富的生物資源，還提供我們許多生態系服務，是重要的生態系統之一。臺灣擁有許多的濕地，這些濕地同時也是各種鳥類重要的棲息地，更是提供許多南遷北往的候鳥們過冬、繁殖與過境補充能量的中繼站。蘭陽溪口濕地位於臺灣的東北部，擁有豐富的鳥類資源，近年來觀察到水鳥群集與環境的改變，因此本研究希望探討地景變化對水鳥群集的影響。利用1989年9月至1990年8月與2015年1月至2016年12月兩時期的鳥類資料，比較兩時期水鳥組成與群集的差異，探討其族群數量變化與生物特性（遷徙屬性、科別）、生態同功群、樣區外趨勢的效應、棲地利用多樣性等因子的關係，並藉由兩時期的地景資料了解蘭陽溪口河道內的棲地變化，希望得知地景變遷與水鳥之關聯。
在地景方面，本研究發現兩時期全區河道內，最大面積都是水域，其次皆為灘地，灘地中又以沙洲為最主要類型；面積增加最多分別是植生地與灘地。以河道下游而言，1989年時以水域和灘地為主，僅非常少許植生地，但2016年時植生地大幅增加成為最大面積的的地景，水域及灘地則面積約略相同，位居第二及第三。沙洲的形式差異最明顯的是河道下游南岸的部分，大多有植生地在周遭區域或圍繞。在水鳥組成的部分，兩時期共紀錄115種，僅有大約三分之二是相同的種類，新紀錄的種類以雁鴨科與冬候鳥為主。兩時期數量等級分布顯著不同，總體蘭陽溪口兩個時期的水鳥群集在數量上有減少的趨勢。水鳥族群趨勢減少有39種，增加有36種，若以兩時期共同出現的種類79種裡，有26種是減少，13種是增加。蘭陽溪口濕地水鳥的族群趨勢變化與遷徙屬性、科別兩生物特性有關連，且「生態同功群」與「樣區外的趨勢」可能是影響的因子，族群趨勢減少的水鳥常傾向與「過境鳥」、「鷸科」、「鷸鴴類」及「國際趨勢或臺灣整體的數量同是減少」有相關，趨勢增加的水鳥常傾向與「冬候鳥」、「雁鴨科」、「游禽類」及「國際趨勢或臺灣整體的數量同是增加」有相關。本研究推測因為沙洲植生地的增加，使得水域周遭需要植被之游禽類的族群趨勢有增加的傾向，其中主要是部分雁鴨科的種類數與多數雁鴨的數量隨之增加，而這些植被提供雁鴨休息、理毛、避敵等作用。另一方面，在蘭陽溪口族群趨勢減少的鷸鴴類可能與國際族群趨勢的減少與沙洲的狀態有關聯，國際趨勢減少與蘭陽溪口覓食灘地減少兩因素，使部分鷸鴴類隨之減少。蘭陽溪口的棲地與鳥類相正在快速的變化中，不論是受到人為影響或自然演替，然而如何能夠維護棲地以保護這個物種豐富的野生動物保護區是刻不容緩的議題。

關鍵字

鳥類 ； 族群 ； 時間變異 ； 棲地 ； 同功群

並列摘要

Wetland has lots of biological resources and provides many ecosystem services for human beings, which is one of the important ecosystems in the world. There are many wetlands in Taiwan, where are important habitats of waterbird for wintering, breeding and transit refueling. The Lanyang River Wetland located in the northeastern part of Taiwan has high bird diversity. The waterbird assemblage and environmental change have been observed in recent years; however, there is no clear evidence for their relationship. Therefore, this study aims to explore the impact of landscape changes on waterbird assemblages using bird survey data and landscape images from two time periods: September 1989 to August 1990 and January 2015 to December 2016. The study further explores waterbirds population trends based on their biological traits (migration status, Families), ecological guilds, population trends outside of Lanyang River Wetland, and habitat diversity index (HDI).
Results showed that water areas constituted the largest part of landscapes across two time periods, followed by tidal flat, which the major type was sandflat. The most increasing area of landscape character was vegetation and tidal flat; in downstream region, the water areas and tidal flat were the major landscape characters, the vegetation area was small in 1989; however, in 2016, vegetation became the major types, and water areas and tidal flat remained nearly the same. Most of sandflat were surrounded by vegetation.
A total of 115 species were recorded, and only about two-thirds of them were present in both periods. The new recorded species were mainly wintering and Anatidae species. The distribution of species among abundance classes in the two periods was significantly different. Overall, the population of waterbird in both periods was decline, 39 species of population were decreasing and 36 species of population were increasing.
Waterbirds population trends in Lanyang River Wetland were related to migratory status and families. The “ecological guilds” and the “population trends outside of Lanyang River Wetland” may be the factors of influence. Population decreasing waterbirds tended to be transit birds, Scolopacidae, shorebirds and international trends or the overall number of Taiwanese declining. Population increasing waterbirds tended to be winter migratory, Anatidae, waterfowl and international trends or the overall number of Taiwanese increasing. This study speculated that increasing trends of waterfowl may result from the increase of shady vegetation. Among them, the richness and abundance of Anatidae increased. Vegetation may provide a habitat for ducks to rest, groom and avoid their predators. On the other hand, the population decline of shorebirds might be related to the reduction of international population trends and the quality of sandflat. In conclusion, this study indicated that habitats and waterbird assemblages of Lanyang River Wetland are shifting quickly, and how to protect this species-rich wildlife wetland is an urgent issue.

並列關鍵字

Waterbirds ； Populations ； Temporal variation ； Habitat ； Guilds

參考文獻

Bai, Q., Chen, J., Chen, Z., Dong, G., Dong, J., Dong, W., Fu, V. W. K., Han, Y., Lu, G., Li, Y., Liu, Y., Lin, Z., Meng, D., Martinez, J., Ni, G., Shan, K., Sun, R., Tian, S., Wang, F., Xu, Z., Yu, Y.-T., Ying, J., Yang, Z., Zhang, L., Zhang, M., Zeng, X. and China Coastal Waterbirds Census Group. 2015. Identification of coastal wetlands of international importance for waterbirds: a review of China coastal waterbird surveys 2005–2013. Avian Research, 6: 1-16.

Colwell, M. A., and Landrum, S. L. 1993. Nonrandom shorebird distribution and fine-scale variation in prey abundance. The Condor, 95: 94-103.

Conklin, J., Verkuil, Y., and Smith, B. 2014. Prioritizing Migratory Shorebirds for Conservation Action on the East Asian-Australasian Flyway. WWF-Hong Kong, Hong Kong.

Euliss, N. H., and Harris, S. W. 1987. Feeding ecology of northern pintails and green-winged teal wintering in California. Journal of Wildlife Management, 51: 724-732.

Goss‐Custard, J. D., and Yates, M. G. 1992. Towards predicting the effect of salt-marsh reclamation on feeding bird numbers on the wash. Journal of Applied Ecology, 29: 330-340.