Herdade da Ribeira Abaixo
Montado Coastal Mountains
On the left bank of Sado River, in Baixo Alentejo province, 100 km south of Lisbon and 7 km from Grândola.
|Soil and topography||
The property lies in the western limit of the hercinic schists of the Paleozoic and the main soil type is a skeletal lithosol. Altitude ranges from 150 to 240 m, with slopes between 5% and 10% (1/3 of the property) and from 20 to 45% (2/3 of the property).
The bioclimate is considered subhumid, mesothermic. Mean average annual rainfall is 500 mm; mean annual temperature is 16°C.
Cork oak dominant, with an average of 43 adult trees per hectare.
|Past history of use||
Managed as an agrosilvopastoral system until the 1940s; since then subjected to a progressive abandonment process that has lead to the low intensity exploration that continues today.
Since 1990, there is a single main economic output - cork, which is harvested in a 9-year cycle, with an average production of 450 kg (dry weight) per hectare per year. Since 1998, cattle herding was abandoned and substituted by sheep, with an average stocking of 0.1 animals per hectare. Recently (2003 and 2004) the property was subject to management actions aiming to foster the natural regeneration of cork oaks; cork oak saplings were also planted in a recently burned area. The shrub layer is cleared heterogeneously across the property every 4-5 years.
|Main drivers of change||
A serious tree decline is observed, especially in the high plateaus. Natural regeneration is not uniform, being concentrated in north facing slopes with a dense shrub layer. Ovine grazing, though of low intensity, is partly responsible for lack of regeneration. Holm oaks are rare in the property, but are increasing. Parts of the property were burnt repeatedly (the more recent fires happened in 2001 and 2003); however some of the north facing slopes maintain a luxurious mixed oak forest and were not burnt in the last 30 years. In these areas, shrub cover and height are increasing.
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