| 摘要: | 景觀生態學主要在於了解大區域範圍的生態功能，與推測生態系統、棲地，或群落的空間配置所帶來的生態影響。空間配置可以景觀結構來描述，即組成景觀的元素類型、多樣性及空間關係。邊緣通常是自然產生在兩個生態群落的介面上，自然過程形成的嵌塊體通常是不規則的複雜形狀，而人為形成的嵌塊體則反之。目前的文獻中討論，邊緣效應的表現與嵌塊體形狀之間存在著重要的關係，邊緣彎延多曲折的形狀，容易促進內部與周邊環境的相互作用，因此，一些研究認為圓形嵌塊體，應該會比線性嵌塊體能更佳的保護內部棲地。但是嵌塊體形狀、邊緣特徵（形狀、寬度、穿透性等）對生態過程的影響目前都僅止於邏輯推論，實際的案例研究、操作尚很缺乏。
台中大肚山台地為一明顯受人為與自然干擾影響之區域，台中地區快速發展擴張，所以聯絡道路鋪設的需求讓許多的交通幹道經過此地，進入大肚山台地之人為活動亦逐日增加，此外，早期因人為需求而引入大黍栽植，在乾濕季分明的氣候條件下，助長大黍引發火燒進而入侵相鄰的相思樹林。在上述人為嵌塊體與自然嵌塊體交錯，以及相鄰嵌塊體之間有明顯相互作用的景觀空間配置之下，使火燒的機率上升不少。所以是探討不同土地利用類型之相鄰邊緣特性，如何影響嵌塊體之間相互作用的最佳研究區域。
本研究探討台中大肚山台地不同類型之相鄰邊緣景觀變遷，比較1977、1985、1997、2002年間的土地利用類型，將土地利用類型分為森林、疏林、草生地、農耕地、道路、開發地、墳墓、裸露地等八種，以GIS整理數化每一年度的邊緣相鄰情況，並逐一檢視到下一個年度後在邊緣兩旁的土地利用發生了什麼改變，歸納出不同土地利用相鄰類型的變遷趨勢。同時以碎形維度檢驗邊緣型狀之複雜度對於不同類型之相鄰邊緣的景觀變遷，是否有影響。
結果發現森林、疏林、草生地與農耕地容易受到相鄰嵌塊體的變遷影響，而跟著一起變遷，（1）森林/ 疏林、森林/ 草生地與疏林/ 草生地之邊緣兩側大多都會變遷為草生地，（2）農耕地/ 道路、農耕地/ 開發地之邊緣兩側容易與相鄰嵌塊體一起變遷為道路或開發地；道路、開發地與墳墓則是不容易受到相鄰嵌塊體的影響，幾乎都能維持原貌不變。另外，兩嵌塊體之相鄰長度越長，越容易互相影響；而碎形維度對於景觀變遷的影響則不顯著。
綜合上述，整體大肚山台地之景觀變遷，明顯受景觀空間配置（結構）之影響，相鄰嵌塊體之間有明顯的相互作用，尤其是森林與疏林變遷為草生地的變遷趨勢最為明顯，因為大黍易引發火燒而波及鄰近的相思樹林。所以應該避免相思樹林與大黍相鄰，可以設置防火帶等緩衝空間，並且改善相思樹林邊緣的植生狀況，增加林下的蔭蔽程度。因為禾本科的大黍生長需要充足的日光照射，所以可以減少大黍生長於相思樹林之間的機會，減少枯萎形成的輕質燃料量累積於相思樹林之中。
Landscape ecology studies the ecological functions of the regional and the ecological impacts of ecosystem, habitat, or community space configuration. Space configuration can be described by landscape structure, including the landscape composition, diversity and spatial relationships. Edges are usually embedded in the interface of two ecological communities. Naturally formed patches are usually irregular and have complex shapes, and human formed patches usually have more simple shapes. There has been discussion on the relationships between edge effects and patch shape, such as curved edges being easier to promote the interaction of the internal of patches and the surrounding environment. Therefore, some researchers believe that round patches provide better physical protection of internal habitat. However, the effects of edge characteristics on ecological processes have limited empirical studies to support such claims.
The Dadu platform in Taichung is significantly affected by anthropogenic and natural disturbances. Rapid development and expansion of Taichung City have led to many major roads passing through Dadu tableland. Also, (2)early human introduction of Panicum maximum planting, contributed to frequent Panicum maximum caused the fire, under the distinct wet and dry season weather conditions have resulting in the invasion of adjacent Acacia confuse forests, such a mosaic of man-made patches and natural patches increases interactions between landscape patches and increases the probability of fire spread, and offers a case study to explore the dynamics between different land uses adjacencies to.
This study investigated the the Taichung Dadu tableland of different types of adjacent edge of the landscape changes, the comparison between 1977, 1985, 1997, 2002 years of land use types, land use types are divided into forest, sparse forest, grassland, farmland, roads, developed land, graveyard, uncovered land, finishing for each year of the edge adjacent to the eight kinds by the GIS, and one by one view to the edge on both sides of the land use of what might have changed in the next year, summed up the different land uses adjacent to the type of the changing trend. The effect of complexity of the edge on landscape changes is tested using fractal dimension.
The results showed that forest, sparse forest, grassland and farmland are vulnerable to the influence of adjacent patch changes, such as （1）if the patch adjacent to sparse forest changes to grassland, sparse forest patch is also easily changed to grassland; （2）roads, developed land and graveyard aren’t susceptible to the influence of adjacent patches, and is almost able to maintain the original type. In addition, the longer the length of the edge, the more likely influence each other; the effect of fractal dimension on landscape change isn’t significant.
Overall the Dadu tableland landscape change is significantly affected by landscape spatial configuration (structure). The interaction between adjacent patches is most obvious on the edges between forest, sparse forest and grassland, because Panicum maximum easily causes fire spread to the neighboring Acacia confusa. So Acacia confusa and Panicum maximum adjacency should be avoided, and the buffer space can beset with fire breaks. The vegetation on Acacia confusa edges, can also be increase to enhance shading of the understory, and reduce the growth of Panicum maximum. |
