Placed in the south limit of the Central Alentejo, from which spread the peri-plains of the Low Alentejo, the mountains of Portel, before the surrounding fields, presents higher precipitation values and a slight smoothing of the temperature. These factors associated to the isolations of some mountains and to the difficult access to some more inclined slopes, contributed to the development of some thick and luxuriant vegetation communities which appear to have been spared to the generalized land cleaning in the Alentejo, led in the 30s by the wreath campaign. In some recessed valleys of the mountains it’s still possible to find some remains of the potential vegetation, that is, the mixed woods of holm-oaks and cork-trees, with a rich undercover composed by arbutus bushes, carrasco (kind of holm-oak), myrtle, privet, dogwood, white-brushwood, several ivies and some orchids. In other areas, more exposed to the permanent action of pasture and agriculture, the forest density tends to diminish and the luxuriant and varied bushes are often replaced by sargasso, brooms and rosemary.
Climate
The mountains of Portel present a Mediterranean climate with prolonged dry and hot periods, alternated by fresh and moist periods. In winter the temperatures can be negative, there are several microclimatic changes associated to the diversity of physiographic situations.
Geomorphology
This is a mountain massive with a schist-greywacke origin. The Mountains present a maximum height of 1377ft and a soil type diversity among which appear several Mediterranean soils, litho-soils and alluvial-soils. However, those occupying a greater extension are the litho-soils (schist skeletal soils).
Flora
Beliz (1990) made the inventory of about 680 vegetal species. We can verify high vegetal community diversity associated to the holm-oak and cork-tree plantations and that here appears a set of unusual or even rare plants in the whole country, clearly resulting from local microclimates and from the soil type profusion.
Fauna
Rich fauna community namely of birds and predator mammals. In the whole set the existing communities is a representative sample of the natural conditions of the Central Alentejo.