The Landes de Gascogne forest, located in southwestern France, spans nearly 10,000 km2 and consists largely of maritime pine (Pinus pinaster). This forest in unique to Europe because it is almost entirely created and managed by man for specific industries. On the basis of a material flow analysis, we assessed the upstream supply chain of maritime pine from 2013 to 2019, using a cradle-to-gate approach. The assessment is based on data provided by Alliance Forêts Bois, an important stakeholder of the region and leader in the production of forest resources in France. For various reasons, the harvest totals decreased 10% in the last years. We identified a clear orientation to specific industries—in 2019, 45% was used as pulpwood. This is due to the overall design of the current territory, species of tree, and market values of the pulp and paper industry. The current design provides a limited supply of old growth trees, which produce high-quality logs for construction-based products, and are also more resistant to climate variability. A future shift or balance in raw material flows could be a crucial step in protecting the long-term economic viability of the region. This article aims to contribute to new attempts in providing comprehensive views of stocks and flows in the French forest-wood supply chain.