花蓮海岸林土地利用變遷與林分發展之研究

A Study to Dectect the Land Use Change and the Stand Development In Hualien Coast Forest.

趙明君(Ming-Chun Chao)

指導教授 ： 邱祈榮

國立臺灣大學/生物資源暨農學院/森林環境暨資源學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.01149

摘要

海岸林為海岸地區重要的自然環境屏障，然而，近年來由於社會對於海岸地區的遊憩及開發的各種需求，加上長期東北季風及颱風等自然災害對海岸林的干擾造成部分地區林相老化乃造成海岸林面臨空前的壓力。查閱過去對於海岸林的相關研究僅著重於林木本身的生理相關研究，缺乏在空間及時間變遷的研究。因此，本研究乃選定花蓮三棧溪口至七星潭約2500公頃區域的海岸地區，利用三個不同時期的土地利用變遷分析，來探討海岸林在土地利用變遷過程中所扮演的角色。研究過程中首先建立1978年、1992年及2002年分為16種地景類型的土地利用圖層，再透過圖層套疊及地景指數的分析方法來探討變遷情形。由不同時期的土地覆蓋圖結果得知自1978年到1992年已有4.4 ha之闊葉混合林，直到2002年面積漸增至38.9 ha。為進ㄧ歩瞭解闊葉混合林分布、擴大之原因，故以德燕海岸林約20 ha之林分，利用遙測技術繪製海岸林分孔隙形成階段之分布情形。利用所建立的不同孔隙形成期分布圖，一方面進行植群調查分析以探討不同孔隙形成期區內的植生有無差異，另外則進行植群光譜分析以暸解不同樣區的光譜差異情形。研究結果顯示不同形成時期的孔隙其植群分別為：孔隙形成在3年內為月橘-木麻黃林型、5~7年為月橘-血桐-木麻黃林型、7年以上則以芒草-血桐-構樹林型為主，可做為未來判斷孔隙形成時間的指標植物。另外，由植群光譜分析結果得知近紅外光及植生指數最能分辨出植群之間之差異。研究中亦發現當木麻黃林內有孔隙形成，而多次颱風侵襲的災害已高於木麻黃林回復的能力，則導致海岸地區孔隙逐年擴大，最後演變為芒草-血桐-構樹林型。故後續若能利用此遙測技術，持續針對其他地區之海岸林進行監測，以及早並進一步瞭解海岸林之分布、結構等情形，以供作經營、復育等決策參考之用。

關鍵字

海岸林 ； 土地利用 ； 變遷分析 ； 孔隙 ； 颱風

並列摘要

Coast forest is an important natural environmental area. However, in the recent years, the needs of the public to develop the recreational area in the coast are increasing. Additionally, natural disturbance such as long-term Northeastern monsoon and typhoon cause the stand aging problems in partial area have caused unprecedented pressure to the coast forest in some areas. The previous studies only focused on the tree physiology and lacked doing research on the spatial and time change. Therefore, this research investigated the land use change in three different periods of the area from Sanjhan River to Chi-Shin Lake in Hualien , about 2,500 ha coastal area to probe into the role that the coast forest acting in the land use changing process. First of all, the aerial photographs of 1978, 1992 and 2002 were digitized and classified into 16 land use types. The layers were overlaid and the landscape index was applied to detect the changes. According to the result, from 1978 to 1992, the gaps of the pure Casuarina spp which were 4.4 ha, grew into 38.9 ha from 1992 to 2002 because of . The research is to comprehend the reason why the type of mixed Broad-Leaved Trees expanded. Consequently, I selected the coast forest in Deyan, which is approximately 20 ha as my study area and digitize the distribution of forest gap’s formation using the Remote Sensing measurement technology.Utilizing the different periods gap’s distribution map, I conducted vegetation investigation and analyzing to comprehended difference between gap distribution maps of different periods; on the other hands, vegetation spectral analysis was used to underatand the spectrum difference between all plots. The result shows that gap formed in three years was classified to be Murraya paniculata-Casuarina equisetifolia type, gap formed in five to seven years was Murraya paniculata- Macaranga tanarius-Casuarina equisetifolia type, when gap formed reach above seven years, vegetation type was Miscanthus floridulus-Macaranga tanarius-Broussonetia papyrifera. Accordingly, it can serve as an indicator species to estimate the gap formation in different periods. Additionally, in vegetation spectral analysis, NIR and NDVI showed a significant difference between different vegetation types. In this study area, the formation of gaps were found and the impact of frequency typhoons were higher than the recovery ability of Casuarina spp. stand. With this two reasons, the gap of coast forest expended and finally Casuarina spp.stand became to the Miscanthus floridulus-Macaranga tanarius-Broussonetia papyrifera type. If we use the Remote Sensing measurement technology to monitor the coast forest in other areas, the distribution and structures of the coast forests will be useful in decision of managing forests and replying conservation in the future.

並列關鍵字

coast forest ； land use ； change analysis ； gap ； typhoon

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