Growing exclusively in the western Mediterranean basin, especially in Portugal, Spain, Morroco and Algeria, the vast majority of the cork oak trees forms a unique ecosystem and cultural landscape (i.e., human-made) called the Montado de Sobro. Characterized by a sparsely populated tree area (ca. 80 trees/hectare), resembling an African Savannah, the cork oak trees and the interspersed areas, occupied by cistus, sargasso, and genista (ca. 55%) sometimes by pastures (ca. 40%) or less frequently by cereal crops (ca. 5%), are the home of one of the 35 hotspots of the biodiversity worldwide like the Amazon. It differs from other areas of greater cork oak density due to its multifunctional economic use (forestry-pastoral and agriculture), which enhances the conditions for a greater presence of fauna and flora. Therefore, in the Montado de Sobro lives 24 species of reptiles and amphibians, more than 160 species of birds, 37 species of mammals and an average of 135 different plant species for each square kilometre. It is also here that it can be found the last refuges of several endangered species like the Iberian Imperial Eagle and the Iberian Lynx.

Potential distribution of the cork oak tree in the World
Source: OLIVEIRA, Manuel Alves; OLIVEIRA, Leonel Moreira – A cortiça. Lisboa: Grupo Amorim, 1991.

The secular economic exploration of the Montado de Sobro, which is still dominant, maintains the ecological equilibrium of the ecosystem and plays a fundamental role in water retention, soil conservation and, above all, carbon sequestration. This is mainly due to the maintenance of the trees in the process of obtaining the most valuable raw material of the Montado de Sobro, the cork. Every nine years, between late spring and early summer, the cork oak tree is stripped from its bark and the subsequent regeneration begins. Although this process causes some stress in the cork oak tree, it also mobilizes natural resources one of them being carbon dioxide (CO2) and, according to the Portuguese Association of Cork, for each ton of cork removed from the tree, there is a direct rescue of 73 tons of CO2 from the atmosphere. Thus, the Montado de Sobro is responsible, every year, for the capture of more than 4 million tons of CO2 in Portugal and nearly 14 million tons in the western Mediterranean basin. Additionally, the industrial transformed cork continues to retain the carbon, between other greenhouse gases, and, theoretically, can be reused continuously through the process of cork agglomeration. Therefore, a cork stopper, the principal product of the cork industry, retains 6,2 gr of CO2, but, with recycling, it has a potential that ranges from 112 to 250 gr. In another perspective, the water retention and soil conservation prevents the advance of desertification, mainly in North Africa, but now also in the Iberian Peninsula.

Montado de Sobro in southern Portugal (Coruche)
Source: Tânia Prates and Municipality of Coruche

The economic vitality of the cork sector, that in 2019 represented over 1.000 M € of Portuguese exports, is the base of the employment of many rural areas in the inner Iberia, between cork strippers, industrial workers and services related to other products of the Montado de Sobro system – production of honey and wax, collecting of mushrooms, hunting, tourism, etc. In fact, the biodiversity of the Montado de Sobro allows a vast panoply of natural products historically used by local populations with an increasing market value today, but still, in my opinion, undervalued. This is the case, for example, in the food industry with asparagus, an ingredient present in many typical Alentejo dishes, as well as with tubers and other fungi. In another perspective, aromatic herbs and medicinal plants are also recollected in the interspersed areas with uses that go from teas (thyme), perfumes (rock rose), spices (oregano) and medicines (green rosemary).  Therefore, the Montado de Sobro is also an instrument of human fixation and regeneration of generations in regions of low population density.

A group of cork strippers in the early 20th century in southern Portugal (Montargil)
Source: Silva, Faísca, Carapinha.

Guardian of biodiversity, keeper and rescuer of greenhouse gases, fighter against natural and human desertification, the Montado de Sobro ecosystem is of an incalculable environmental, social and economic value, but also a very fragile one. It was born, in the late 18th century, out of a human need in a context of extreme edaphic-climatic conditions and with soils with minimal organic matter, but where it was possible to create an economic and ecological sustainable system. However, presently it is at risk with marked mortality of trees in traditionally cork oak areas, which can be linked, among other factors, to the use of unskilled labour in the stripping of cork, the occurrence of prolonged droughts and the dissemination of pests, these last two probably related to climate change. With such importance in the territories where it subsists, it is essential that farmers, landowners, scientists, politicians and other citizens join forces so that the cork oak forest remains as it has happened in the last two hundred years.

Carlos Manuel Faísca