大漢溪河岸林、工業區外濕地與水牛族群的共存

Coexistence of Taiwanese Water Buffalo in the Dahan River between Coastal Wetland, Urban Forestry and Industry Area

胡正恆(Cheng-Heng Hu)

《華岡農科學報》 46期 (2020/12) Pp. 75-90

摘要

大漢溪流域是大臺北都會林區內仍有水牛（Bubalus bubalis）棲息的區域。此地的水牛主要在溪谷人工林與高灘草地間棲息，包含馴化水牛再野化之後代，在近十年間從6頭繁殖為30餘頭。自2020年6至9月橫跨夏／秋兩季，每周針對樹林鹿角溪之水牛主要覓食區以及土城媽祖田的河濱夜宿地，進行野化水牛族群之組成掃描與最大數量取樣，共計數到33隻牛，並有一公一母之成年牛有項圈可追蹤。包含17隻成牛、13隻幼牛以及2020年9～11月間出生的3隻仔牛。牛群偏好在樹林工業區外的淺池泥浴避熱，並利用廣大河濱覓食；從土城工業區遠眺，常見大群夜宿於三峽河匯入大漢溪的沙洲，棲地內目前共記錄7種82棵樣木，以株數來看，優勢種包括苦楝（Melia azedarach）（32株，39%）、銀合歡（Leucaena leucocephala）（25株，31%）、水柳（Salix warburgii）（12株，15%）。另外，樹幹具有臺灣水牛磨剝痕跡的株數有33棵，磨剝比例為40.2%，以銀合歡的受磨剝株數最多，共23棵。卡方獨立性檢測發現，大漢溪臺灣水牛磨剝行為與樹種及樹徑具有顯著偏好性（p＜0.05），值得持續進行監測，為防治水牛磨剝工作進行準備。監測過去三年（2018－2020年）的植生變動，則以大地衛星（Landsat）的多頻譜影像，估算標準化植生指數（NDVI）後得出：春夏季（3～8月）持續受雨季的浸潤，NDVI指標高居0.4～0.8間，顯示為林／草地植被密集，光合生產力高。至於秋冬是枯水期（9～2月），半年內草木凋零。尤其是2019年的東北季風曾帶來洪水，當時觀測植生指數由夏季高點的0.6降低至0.2，為草料匱乏時期，並歷經六個月後才恢復到原有基礎水準。此一樹林工業區外圍的水牛棲地，曾有秋季的短期排水，使濁度升高到2347±264mg/L，是夏季正常濁度的13.5倍。酸鹼值在夏、秋季間，也較偏鹼性（pH=7.92±0.96,n=19）；並可觀測到該地氧化還原電位顯著較低，應為受森林遮蔽，加上牛池底泥受攪動而更顯還原態，有助淨水效能提高。此外，水牛於工業區外圍濕地之掘地活動，與其所帶動的底泥翻攪，有助於礫間曝氣與水質淨化。本研究從關懷動物棲地的整全角度出發，監測樹林、土城工業區外圍的河濱公園林草地，需要考慮到觀賞水牛的市民休閒健康、溼地植生保育、以及環境保護林的生態貢獻。

關鍵字

臺灣水牛（Bubalus bulalis） ； 棲地利用 ； 樹林區 ； 土城區 ； 濕地化學 ； NDVI

並列摘要

The Dahan River is an area where Taiwanese Water Buffalo (Bubalus bulalis) inhabits in the metropolitan forest area of Taipei City, Taiwan, including the re-wild generation of domesticated buffalo, which reproduced from 6 to more than 30 in the past decade. From June to September 2020, across the summer/autumn seasons, the main foraging area of the buffalo in Antler Creek in the woods and the riverside overnight accommodation in Matsu Field in Tucheng were scanned for the composition of the wild buffalo population, and The largest number of samples were sampled and a total of 32 cattle were tracked, including 17 adult cattle, 13 young cattle and 2 calves born in the summer. There is a male and a female adult cattle with collars to track. The cattle prefer to avoid the heat in the shallow mud baths outside the Shulin Industrial Zone and use the vast riverside for food. After monitoring the vegetation changes in the past three years (2018-2020), using Landsat multi-spectrum images, the standardized vegetation index (NDVI) is estimated and the result: Spring and summer (March to August) continue to be infiltrated by the rainy season , NDVI indicators are all high values between 0.4 and 0.8, indicating dense forest/grassland vegetation and high photosynthetic production. As for autumn and winter is the dry season (September to February), the vegetation withers within half a year; however, the northeast monsoon in 2019 brought floods, and the observed vegetation index decreased from the summer high point of 0.6 to 0.2, indicating that the vegetation abundance was only 1/3. It was a period of forage scarcity, and it was restored to the original basic level after six months. In addition, the excavation activities of the buffalo in the wetlands outside the industrial area, and the muddy and biochemical reactions that it drives, contribute to the aeration between the gravels and the purification of water quality. Outside the Shulin Industrial Zone, there was a short-term drainage turbidity that increased to 2347±264 mg/L in autumn, which was 13.5 times the normal turbidity in summer. The acid-base value of the forest area is also relatively alkaline in summer and autumn (pH=7.92±0.96, n=19), and it can be observed that the redox potential of this area is significantly lower. It should be that Niuchi is sheltered by the forest. The bottom sludge is reduced to a reduced state and the water purification efficiency is high. This research starts from the perspective of caring for the completeness of animal habitats, and monitors the forests and the riverside park forests and grasslands outside the Tucheng Industrial Zone. It is necessary to consider the leisure and health of the citizens watching the buffalo, the wetland plant conservation, and the ecological contribution of healthy urban forests.

並列關鍵字

Bubalus bulalis ； habitat use ； Shulin District ； Tucheng District ； wetland chemistry ； NDVI