Sweet Chestnut

Castanheiro (sweet chestnut, Castanea sativa Mill.) is a medium to large deciduous tree that may reach 30-35 m when cultivated, and can live up to 1000 years.

Although doubts arise about the plant’s origin in the Western Mediterranean, its presence in the region is usually admitted from the Roman Period onwards. In Europe, it can be found in Italy, France, Spain and Portugal. It is cultivated for various purposes such as timber and fruit production. Thriving in warm-temperate climates, it requires a minimum level of rainfall and optimal growth is observed at lower elevations in higher latitudes. Highly susceptible to summer droughts, resulting from a combination of high temperatures and insufficient precipitation, it also displays sensitivity to late frost but exhibits a strong adaptation to environments prone to fire disturbances. Even after the trunk becomes hollow due to rot, it retains its capacity for vegetative regeneration. 

Sweet chestnuts are harvested during the winter using a saw machine. After cutting the wood, it has to be heated, and the bark removed. Afterward, it is split, soaked, and flattened before starting to work with it. It is a wood with little hardness, thus elastic and flexible. It is less resistant than oak, but is easier to work with and more stable. It is easy to saw, split, polish, screw and stain, and curves well in dry conditions and poorly when green. Requires slow and careful drying due to the tendency to warp and crack, and resists fungal attack – but sapwood is sensitive to insects. Given its resistance to bad weather, it is used outdoors, for example for posts or stakes.

In Portugal, the main reason for its cultivation is also the production of chestnuts. Historically, the fruit of the chestnut tree was structural in the Portuguese diet, particularly in the north of the territory and even today national production is concentrated in Trás-os-Montes, although it is found in all mainland provinces, namely parts of the Beiras, Portalegre, and Monchique. Old growth forests are known to be good carbon sinks, therefore old chestnut parcels (mainly for fruit production) should be preserved at any cost. These deciduous forests provide relevant ecosystem services and are aesthetically pleasing, especially when autumn colours arrive into these woodlands. 

While numerous wood producers and suppliers operate in Portugal, basket weavers commonly opt to personally harvest the wood, and sweet chestnut is one of the types of wood used in wood splint basketry.

Mostly crafted in the central and northern coastal regions of Portugal, these baskets are considered rugged baskets and are traditionally used for harvesting, farming, and fishing. The wood splint basketry technique requires the largest number of tools, typically consisting of rudimentary and old equipment. When done in the traditional manner, using a basket-weaving bench, it involves a long preparation period, and the craft is primarily carried out by men. The material is 100% biodegradable if not mixed with any chemical product or material.