由生物地形學觀點探討關渡自然保留區的紅樹林分布變遷

Mangrove Distribution Change in Kuantu Nature Reserve from the Perspective of Biogeomorphology

許立志(Li-Chih Hsu) ； 李建堂(Cheing-Tung Lee)

《中華林學季刊》 46卷1期 (2013/03) Pp. 87-105

摘要

本研究透過航空照片判釋及地形變遷分析，由生物地形學的觀點探討1994－2005年間關渡自然保留區紅樹林變遷的作用機制與過程。研究結果顯示，植群組成以水筆仔為主、蘆葦為輔之林澤地，水筆仔所占總值群面積的百分比由1994年的60.51%增加到2005年的78.91%，顯示植群組成有趨向單一化發展的趨勢。植群變遷以蘆葦轉變為水筆仔及堆積灘地轉變為水筆仔之現象最為明顯。地形變遷之特徵，包括了潮流溝的向上游加長、擴張以及堆積灘地的擴張，有利於水筆仔散布、擴展其生育地範圍，進而取代蘆葦生育地和堆積灘地的範圍。原本1994年蘆葦分布面積的45.50%（6.52 ha），於2005年轉變為的水筆仔，此應與潮流溝的向上游加長和擴張有關。由於研究區本身地理位置之特性、植物根系之攔砂作用及目前淡水河流域之全面禁止抽砂，導致基隆河道的堆積作用旺盛，使得1994年堆積灘地分布面積中的44.15%（2.30 ha），也於2005年轉變為水筆仔，但是海拔高程0.2m以下的灘地並沒有水筆仔的分布，這可能與潮水淹沒時間較長有關。2001年納莉颱風引發的洪水沖刷，雖然造成紅樹林分布面積減少2 ha，但因研究區的地形堆積作用顯著，以及水筆仔具有自我更新的能力，因此水筆仔很快就回復到先前的分布狀況。

關鍵字

關渡自然保留區 ； 紅樹林 ； 水筆仔 ； 植群變遷 ； 地形變遷 ； 生物地形學

並列摘要

Based on the perspective of the biogeomorphology, this study uses aerial photo interpretation and geomorphologic change analysis to investigate the change of Kandelia distribution in Kuantu Nature Reserve from 1994 to 2005. Results indicate the percentage of Kandelia distribution area to the whole vegetation area increases from 60.51 % in 1994 to 78.91 % in 2005, which indicates that vegetation composition tends to be dominated by single species, the Kandelia. The most manifest vegetation changes are the substitute of Kandelia for Pharagmites and mudflat. Geomorphologic change features of the study area including the headward extension of tidal creeks and the spreading of the mudflat help the dispersal and colonization of Kandelia, which will replace the spreading of distribution area of Pharagmites and mudflat. The headward extension of tidal creeks brings about the substitution of Kandelia for Pharagmites; about 45.50% of the original Pharagmiles distribution areas (6.52 ba) are replaced by Kandelia during the study period. Due to the geographic location of the study area, root effect of the vegetation on sediment accretion and ban on sand pumping in the Tanshui River Basin, the sedimentation is so obvious that the spreading of the mudflat favors the colonization of Kandelia; about 44.15% of mudflat (2.30 ha) in 1994 is substituted by Kandelia in 2005. The distribution of Kandelia is limited to the mudflat areas with elevation greater than 0.2 m. The erosion caused by floods during Typhoon Nari in 2001 had led to the decrease of mangrove area by about 2 ha. However, due to the self-regeneration ability of Kandelia and the significant sedimentation process in the study area, the mangrove recovered fast to its previous distribution area.

並列關鍵字

Kuantu Nature Reserve ； mangrove ； Kandelia candel (L.) Druce ； Vegetation change ； Geomorphologic change ； Biogeomorphology