Dinâmincas geomorfológicas como metodologia básica na avaliação da sensibilidade da paisagem. Aplicação ao Ilhéu de Vila Franca do Campo, S.Miguel, Açores

• Autor(a) principal: Abreu, Maria Manuela
• Data de Publicação: 2002
• Outros Autores: Ribeiro, L., Arsénio, Pedro, Bulcão, L.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.5/5413
• topic: andosoils; morphogenesis; pedogenesis rate; palogonitic tuff; landscape sensitivity; vegetation communities

The Islet of Vila Franca do Campo, (S. Miguel Island, Azores) with 6,2 ha, is located 500 m from the south coast. The geology, ecology, and cultural character, makes it a place with high landscape quality, very attractive for recreation, originating a highly sensitive landscape to recreation impacts. Landscape sensitivity assessment becomes therefore a crucial step in the development of a landscape and management plan, aiming to reconcile conservation with public recreation. The main objective of this work is to show the importance of geomorphology-pedology, together with other parameters (topographic features, plant communities and cultural resources) in assessing Islet landscape sensitivity. The methodology used was based in a parametric approach. Relative values were given to the different classes of geomorphology-pedology, vegetation and topography based on natural value and resistance to recreation use. The overlaying of these values enabled de assessment of the landscape sensitivity. The Islet is a volcanic cone of stratified palagonitic tuffs from the Holocene age. Besides, in the Northwest and South-Southwest summit zones pumiceous deposits with a trachyte composition occur. The exterior hillsides of the volcanic cone (mainly NW and W cliffs) are under intensive wind and marine erosion. The geomorphic dynamics evaluated by means of the morphogenesis/pedogenesis rate allowed to consider the following areas: (a) area on Morphogenesis processes (M). This area is submitted to relative intense ablation processes by creeping and rill erosion. The area correspond mainly to outcrops of palagonitic tuffs or pumice with different weathering stages and a zone with incipient soils; (b) area on Intergrade processes to Morphogenesis (IM) which is associated to steep slopes (>25%) incipient soils or Andosoils where mass movements are observed; (c) area on Intergrade processes to Pedogenesis (IP), located on the summit zone, correspond to Andosoils which can attain 200 cm depth. The Islet’s vegetation was classified according to its structure, dominant plants and natural significance, with special attention given to the communities holding endemic plants. In general, the Islet reveals an high landscape sensitivity, given by its biological, geomorphic, pedological and topographic significant features.