Sweet chestnut – multi-purpose species provides wood and food

Last week, we discussed sweet chestnut as a possible alternative to ash which is no longer planted in Ireland due to ash dieback disease. It has similarities with ash in relation to site requirements, establishment, rotation length and silvicultural treatment but how does it measure up in terms of end uses? Ash has a ready market in furniture and hurley-making but sweet chestnut surpasses it for end uses.

Sweet chestnut lacks the elasticity of ash so will never be used for hurley-making, but unlike ash it can be used both internally and externally from fencing to construction.

Fencing

Sweet chestnut has a naturally durable heartwood and unlike other hardwoods, including oak, it has a narrow band of sapwood so it is an ideal wood for fencing posts even when untreated.

At a field day in Derrinlaur, Co Waterford, earlier this year, Laura Fletcher discussed its resistance to decay. She outlined how a chestnut fence on the farm of Paddy Stokes, near Kilsheelan, dating to 1964 is still in good condition. This is more than double the service life of treated softwood fencing posts.

Construction

A fine example of sweet chestnut in construction is the extension to the Model School in Inchicore by Donaghy and Dimond Architects.

The challenge was to link the new building with the original small national school built in 1853 in limited space while retaining the existing mature horse chestnut trees.

The architects chose sweet chestnut cladding staves on the second and third floors, which cantilever over the ground storey in brick.

Although sweet and horse chestnut are not related tree species, the architects wished to retain the chestnut theme in the overall site design. The leaves and branches of the horse chestnut almost touch the sweet chestnut cladding achieving the architects objective of “extending the learning environment into the tree canopy as the classrooms and surrounds change dramatically with the seasons”.

General uses

In good productive crops, sweet chestnut can be utilised for flooring, furniture, cladding, joinery and even veneer in quality pruned trees from years 35 to 60, depending on yield and form.

It tends to develop shake and spiral grain as it grows older, so maximum rotation should not exceed 70 years.

Fuelwood

While sweet chestnut has a number of advantages over other hardwoods for its range of uses, firewood is not one of them. Ash, oak, sycamore, beech and birch are well ahead of it as a fuelwood. The twelfth century rhyme sums it up as a firewood tree: “Chestnut’s only good, they say/If for long it’s laid away.” And “long” for chestnut could be up to two years and even then it sparks and is not suitable in an open fire.

Non-wood uses

Chestnut is one of the few tree species in Ireland that produces food as well as wood. If you visit Paris and other continental cities this time of year, you can purchase delicious roasted chestnuts from street vendors but peel them before eating. In the past, the nuts were ground to make flour for bread-making. Innovative continental chefs still use the flour as a base for a wide range of dishes including pasta, stuffing and even ice cream.

Although it is not an ideal firewood tree, it has a market even in small wood from early thinnings when it can be used for fencing stakes and light poles, produced from either artificially established or coppiced crops.

In well-formed and productive crops it has more end uses than most hardwoods from flooring to furniture, cladding to wood turnery and joinery to veneer, so sweet chestnut is an ideal substitute for ash on suitable sites.

Teagasc talking hardwoods in Mitchelstown

Broadleaf woodlands planted in Ireland since the early 1990s should now be approaching harvesting from first thinnings. Early intervention, especially thinning, is vital in managing broadleaves to produce a quality crop. “Where forest owners meet hardwood users” is the theme of a major event in broadleaf management organised in the Firgrove Hotel, Mitchelstown, Co Cork, on Tuesday 24 October by Teagasc in association with the Forest Service.

“When growing broadleaf trees, appropriate management, results in the production of quality timber and increased crop value,” said Tom Houlihan, acting head of Teagasc Forestry Development Department.

“Extensive research by Teagasc and others has developed silvicultural techniques, including formative shaping, high pruning, marking of potential final crop trees and thinning at the correct stage,” he said.

The event will cover issues such as early thinning for firewood and woodland improvement which receives an attractive grant. As crops develop through further thinning, it is envisaged that some of the logs from the removed trees will be suitable for higher value end uses.

“Many of these end uses will be showcased at this marketing event,” maintained Tom.

“It is therefore timely for Teagasc to organise an event bringing together broadleaf growers and users of hardwood timber stimulating the development of this fledgling hardwood market in Ireland.”

The event will include a demonstration of a Peterson portable sawmill, presentations by foresters and end users, as well as an opportunity to view quality Irish hardwood products.

Registration will open at 9.30am next Tuesday. It is advisable to register online at https://talkinghardwoods2017.eventbrite.ie to avoid queuing but registration will also be taken at the event.