6 Chestnut wood

Aged chestnut coppice wood, with numerous large trunks that develop from the stumps.

Photo: Museo cantonale di storia naturale.

On soils of morainic origin, poor in carbonates, the dominance of the chestnut tree stands out, accompanied at times by other tree species. like oak and birch. The chestnut wood, present in Switzerland mainly on the hillsides of Ticino, is the product of a transformation of the natural oak and birch wood by man. Until the middle of the last century, chestnut woods were an essential source of livelihood and the chestnut tree was cultivated at the expense of indigenous tree species.
The undergrowth is generally sparse, poor in species and dominated by acidophilic plants, such as blueberries. There are two main forms of management of the chestnut wood: fruit (sweet chestnut) and coppice.

The wood is used primarily for the production of chestnuts, while the coppice, characterised by the presence of trees with more trunks, is intended for the production of firewood and poles, so it’s also often called a pole. Thanks to the high tannin content, the chestnut wood rots slowly and is very resistant to insect attack. It therefore lasts a long time, both as timber in the construction industry, and as poles (e.g. for vineyard support posts).

This form of management, characterised by cuts at regular intervals, exploits the chestnut’s ability to produce vigorous harvests when cut, thanks to the presence of dormant buds at the base of the stumps.

The chestnut woods of Monte Caslano were mainly managed by coppice. As a result of the abandonment of exploitation they are partially aged, as demonstrated by the large trunks that have developed from the stumps. Under natural or management-abandoned conditions, the chestnut tree is uncompetitive and in the long term can gradually be replaced by other tree species.

Ticino’s chestnut populations have also been weakened by the arrival of exotic pests. chestnut blight, for example, is a disease caused by the fungus Cryphonectria parasitica, which originated in East Asia and was accidentally imported in the middle of the last century. Unlike the United States of America, in Europe the disease has had a less dramatic progress, thanks to the greater resistance of the Sweet Chestnut (Castanea sativa) than the American Chestnut (Castanea dentata) and the spontaneous appearance in southern Europe of virulent attenuated fungal strains (hypovirulence).
In 2009, another parasite arrived in Ticino: the chestnut gall wasp, an insect native to China. This hymenoptera induces the formation of roundish swellings (galls) on the shoots and leaves of the chestnut tree, within which the larval development takes place. The presence of galls hinders the production of branches, leaves and fruits, and causes a general weakening of the plant. In the meantime, a parasitoid antagonist of this cynipid has also appeared in Ticino, the hymenoptera Torymus sinensis, also originating in China and whose presence has allowed the population of the chestnut gall wasp to be contained and its impact to be reduced.

Credits: 1, 3, 4: Istituto federale di ricerca per la foresta, la neve e il paesaggio WSL / 2: Filippo Rampazzi