Planting and guided natural regeneration - Saint-Martin-des-Champs (78)

Le Projet

 The project involves forest enrichment and guided natural regeneration across an area of 5.69 hectares in Saint-Martin-des-Champs in the Yvelines department (78), 9 km west of Thoiry and 15 km south of Mantes-la-Jolie, in the Pays des Yvelines and Fontainebleau region. It aims to regenerate three islands of declining or seed-poor stands, spread throughout the Lecoq woodland — a forest whose age has been documented since the 18th century — by planting them with diverse species adapted to a more demanding climate.

Installation of 1,444 plants divided into eight species on three islands with distinct issues: sessile oak and Sequoia sempervirens on island 1 (maple and lime coppice lacking seed trees); Sessile oak, Bornmüller fir and poplars on island 2 (5-year-old forest growth from a poor chestnut coppice); Sessile oak, downy oak, Bornmüller fir, plane maple and wild pear on island 3 (light deciduous forest of dying trees on the plateau). In addition, natural regeneration — 4,668 stems of oak, hornbeam, beech, chestnut, willow, service tree and elm — is being supported across a total of 4.24 hectares in order to enhance the standing capital and strengthen the genetic diversity of the stands. The project is part of a strategy to convert to irregular high forest with continuous cover, enabling sustained production of high-quality timber while respecting existing habitats.

 

Yvelines Department

Saint-Martin-des-Champs is a commune in Yvelines, the most wooded department in Île-de-France with over 68,000 hectares of forest, representing 30% of its total surface area. The project is located in the Paris Basin Tertiary sylvoecoregion, a predominantly agricultural area (53%) where forest covers 28% of the surface area. In the Pays des Yvelines and Fontainebleau, the main tree species are pedunculate and sessile oak, accompanied by hornbeam, beech, chestnut and birch, depending on the nature of the soil. The forests of the Yvelines, including the Rambouillet forest (over 20,000 hectares), are major reservoirs of biodiversity in the Île-de-France region, home to 1,459 plant species and 56 species of native mammals.

The project is located in an area identified for afforestation under the Île-de-France SRCE sub-framework, and is crossed by a temporary watercourse that joins the Flexanville river — a tributary of the Vaucouleurs, itself a tributary of the Seine — classified in List 1 for the protection of watercourses in very good ecological condition and biological reservoirs. It is located in the immediate vicinity of the ZNIEFF Type II ‘Plateau du Grand Mantois et Vallée du Sausseron’, which is home to one of the largest populations of little owls in Île-de-France, as well as hen harriers, mercury damselflies and tree frogs. By restoring forest cover and supporting natural regeneration, the project is actively contributing to maintaining these ecological continuities and preserving the region's aquatic and forest environments.