Autor(es):
Abreu, M.M. 
; Ribeiro, L. ; Arsénio, P. ; Bulcão, L.
Data: 2002
Identificador Persistente: http://hdl.handle.net/10400.5/5413
Origem: Repositório da UTL
Assunto(s): andosoils; morphogenesis; pedogenesis rate; palogonitic tuff; landscape sensitivity; vegetation communities
Descrição
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.
