Considered the “bread tree” in the regions north of the Tagus, the chestnut tree was the staple food before the arrival of the potato and the main source of carbohydrates in the north of the Iberian Peninsula. This deciduous tree can grow up to 30 to 35 metres in height and reach diameters of up to 12 metres, although the trunk becomes hollow as the tree ages. It is very long-lived and can live for over a thousand years.
The European chestnut tree (Castanea sativa Miller) belongs to the Castanea genus and the Fagaceae family, the same family that includes cork oaks and oaks in general. The genus includes 12 to 13 species, five of which are of Asian origin and seven of which are North American. The common chestnut tree is the only one native to Europe. This is a tree that managed to survive the last glacial period (Würms glaciation) in some parts of central and Mediterranean Europe and is currently found all over the world, including North and South America and Australia.
Several studies indicate that the natural distribution of the European chestnut tree corresponds to these refuge zones, where it remained during the glacial events. These areas later served as starting points for the colonization of other regions, before humanity dedicated itself to cultivating the species. One of these refuges is located in the Picos de Europa region and another between the south of Galicia and the north of Portugal, which is why the chestnut tree is considered an indigenous or native species of our country.
The chestnut tree grows well in temperate climates and the ideal conditions for its development are found in places with average temperature and humidity, where rainfall reaches at least 600 mm per year – more than 100 mm in the summer. It is, however, sensitive to late frosts and very low temperatures. It prefers soils at least 50 cm deep, loose and rich in nutrients, slightly acidic (pH between 4.5 and 6.5) and not calcareous.
Although it can grow in less suitable conditions, it develops and produces best in coastal or mountainous areas, at medium altitude, with hot and humid summers and mild winters.