Forest of Tronçais

The forest is located on the southern limit of the Paris Basin, on varied substrates (from the primary to the quaternary eras). Most of the forest is located on sandstone or clay from the triassic period.

Two rivers cross the massif: the Marmande and its tributary the Sologne. The Marmande is a tributary of the Cher which feeds the Loire. There are also five ponds (French: l'étang):

• L'étang de Saint-Bonnet (44 ha) – This natural pond was enlarged at the end of the 18th century to sustain the level of l'étang de Morat.
• L'étang de Tronçais (18 ha) – On la Sologne, created in 1789 to provide energy to the forges of Tronçais
• L'étang de Morat (private) (13 ha) – On la Sologne, downstream of l'étang de Tronçais
• L'étang de Saloup (private) (12 ha) – Upstream of l'étang de Tronçais
• L'étang de Pirot (70 ha) – On la Marmande, this 14-metre-deep (46 ft) pond was in operation in 1848 to feed the canal de Berry via l'étang de Goule.

L'étang de Pirot (December 2011)

There are about 100 spring sources in the forest:

• 
  la font de Viljot
• 
  la font Jarsaud

The land was cleared and intensively cultivated under the Roman Empire. 108 Roman habitations that have been discovered in the forest, most during recent decades. Roman manuring and fertilizing practices created a pocket of increased biodiversity, which has remained self-sustaining over two millennia and can be detected today.[6][7]

Tronçais is first recorded from the 13th century, in a document relating to the priory de la Bouteille.

The forest was first owned by 14 nearby parishes, then yielded in 1327 to the Duke of Bourbon. The Forest of Tronçais has belonged to central power since 1527, when all land possessions were confiscated from the Constable of Bourbon by royal power.[8]

The forest is not a relic of the primeval forest that once covered most of France, but was organized by Jean-Baptiste Colbert in 1670. With forethought for the requirements of the French Navy two hundred years hence, the Colbert Forest was planted as an oak grove. The oaks were interplanted with beeches and larches to encourage their growth for favourable timber for ship's masts: straight, tall, and free of knots.[9]

By the time the trees were fully mature, the navy was rapidly switching from sail to steam. The forest was diminished by the creation in 1788 of iron forges fed by charcoal from the forest,[10] and by urgent cutting during the French Revolution and the Napoleonic period. The forest regenerated during the 19th century.

The oldest trees are in the Colbert forest (French: la futaie Colbert). It is a 13 ha (32 acres) parcel, in two pieces, the main stand in a regeneration from the end of the 17th century. These are classified as a directed biological reserve; lumber is no longer taken in order to favour biodiversity around deadwood and senescent trees.

The Colbert high forest spanned 73 ha (180 acres) in 1976, of which 60 ha were regenerated from 1976 to 2001.

The oaks of Tronçais, representing some 80% of timber production, are prized for the barrels coopered for cognac and the great wines of Bordeaux. This is linked to several elements, found in other national forests of the Loire basin:

• The age management in the high forest allows slender trees which are pruned naturally, leaving relatively few knots in the wood.
• Due to the summer water deficit and the density of the stands, the wood grows slowly, providing a fine and regular grain to the wood.
• The wood has a pink colour and a chemical composition appreciated in a raw (untreated) quality.

Amongst the more famous coopers using the oaks of Tronçais is Dominique Laurent,[11] who makes what are widely regarded as some of the world's finest barrels. These have been nicknamed "magic casks", by wine taster Michel Bettane. Laurent goes into the Tronçais forest to select the trees (typically around 300 years of age) and transports them to the cooperage himself, thus guaranteeing provenance. He uses the top section of the trunk, the staves are split by hand and air dried for 52 months. Due to hand splitting, the staves have a thickness of 40–45 mm (1.6–1.8 in) compared to commercial barrels at 25–30 mm (0.98–1.18 in). The barrels were developed for Dominique Laurent, and Tardieu Laurent's top cuvees, but a few of the barrels are sold to French and international producers including DRC, Zind Humbrecht, Clos Mogador, Pingus and Beau Fréres. A limited number of barrels are exported to Australia where they are used by the boutique winemaker Torbreck for the making of shiraz.