Assessment of Road-Induced Landscape Fragmentation and Implications for Landscape Planning: the case of İzmir Province

Roads are considered as a major environmental problem and one of the main causes of biodiversity loss and landscape fragmentation. Recent evidence suggests that whilst roads generally lead to increasing landscape fragmentation; they also affect the structure and functioning of landscapes through the pollution caused by the vehicles and the acceleration of settlements around road networks. This paper explores the relationship between the presence of roads and landscape fragmentation in the central districts of Izmir province, using landscape metrics at class and landscape level. CORINE land cover (CLC2012) dataset together with Urban Atlas 2012 (UA2012) were used for the delineation of land cover map with and without roads. The analyses were performed in FRAGSTATS 4.2 and ArcGIS 10.5.1. Results illustrated an increasingly fragmented urban landscape with respect to increasing road existence. However, it is important to bear in mind the possible limitations of some landscape metrics when evaluating fragmentation caused by roads. On the other hand, the results of this study emphasise that the number of patches (NP), area-weighted mean patch area (AREA_AM), edge density (ED) and effective mesh size (MESH) seem to be much more robust landscape metric when measuring landscape fragmentation. The paper concludes with important implications and recommendations with a view to informing landscape planning practices for creating opportunities around roads and road networks to support biodiversity and enhance the lives of people. For example, as a practical manner, the creation of roadside vegetation and vegetated verges can reduce the fragmentation effect of road networks and enhance landscape connectivity rather than its fragmentation effect. The care and regular maintenance of these areas will also play an important role in improving landscape quality and promoting biodiversity.

Anahtar Kelimeler:

Fragmentation, Land cover, Landscape metrics, Roads, Spatial pattern

Yollardan Kaynaklanan Peyzaj Parçalanmasının Belirlenmesi ve Peyzaj Planlama Açısından Değerlendirmeler: İzmir İli Örneği

Yollar, büyük bir çevre sorunu ve biyolojik çeşitlilik kaybı ile peyzaj parçalanmasının ana nedenlerinden biri olarak kabul edilmektedir. Yapılan araştırmalar, yolların genellikle artan peyzaj parçalanmasına yol açtığını; ayrıca araçların neden olduğu kirlilik ve yol ağları etrafındaki yerleşimlerin hızla artması yoluyla peyzajların yapısı ve işleyişini de etkilediklerini ortaya koymaktadır. Bu çalışma, İzmir ili merkez ilçelerinde yolların varlığı ile peyzaj parçalanması arasındaki ilişkiyi sınıf ve peyzaj düzeyinde peyzaj metriklerini kullanarak incelemektedir. Çalışmada, CORINE arazi örtüsü haritası (CLC2012) ve Urban Atlas2012 (Kent Atlası2012) (UA2012) ile birlikte kullanılarak, çalışma alanına ilişkin detaylı yol verisinin içerildiği ve içerilmediği arazi örtüsü haritaları kullanılmıştır. Analizler FRAGSTATS 4.2 ve ArcGIS 10.5.1 yazılımlarında gerçekleştirilmiştir. Sonuçlar artan yol varlığının kent peyzajında artan parçalanmaya sebep olduğunu göstermektedir. Ancak, yolların neden olduğu parçalanmanın değerlendirilmesinde bazı peyzaj metriklerinin etkinliklerinin olası kısıtlılıklarını göz önünde bulundurmak gerekmektedir. Diğer yandan, bu çalışmanın sonuçları, peyzaj parçalanmasını değerlendirirken yama sayısı (NP), alan ağırlıklı ortalama yama alanı (AREA_AM), kenar yoğunluğu (ED) ve etkin ağ boyutunun (MESH) peyzaj parçalanmasına ilişkin daha sağlıklı değerler sunduğunu vurgulamaktadır. Çalışma, biyolojik çeşitliliğin desteklenmesi ve insanların yaşam kalitesinin iyileştirilmesi bakımından yollar ve yol ağları çevresinde fırsatlar yaratmak için peyzaj planlama uygulamalarına ışık tutabilecek bazı önemli önerilerle sonlandırılmıştır. Örneğin, pratik anlamda, yol ağları çevresinde yol kenarı bitki örtüsü ve bitkilendirilmiş banketler, yol ağlarının parçalanma etkisini azaltabilir ve peyzaj bağlantılılığını arttırılabilir. Ayrıca, bu alanların korunması ve düzenli bakımı peyzaj kalitesinin arttırılmasında ve biyolojik çeşitliliğin desteklenmesinde de önemli rol oynayacaktır.

Keywords:

Parçalanma, Arazi örtüsü, Peyzaj metrikleri, Yollar, Mekansal yapı,

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