The 2026-2035 crisis management plan for the Château de Chantilly forest has been approved.

The context for the creation of this crisis management plan

For several years now, the forest surrounding the Château de Chantilly has been facing alarming decline.

In 2018, the Institut de France and the Château de Chantilly warned of early deterioration in the health of forest stands, mainly due to a combination of three major factors: repeated episodes of drought and heat waves since 2015, the sandy nature of the soil, which retains very little water, and a severe infestation of the soil by cockchafer larvae.

These cumulative stresses weaken trees in the long term, particularly oak trees, the emblematic species of this ancient forest.

FFaced with this situation, the Institut de France, owner of the estate, decided not to limit itself to the usual management plan, but took the time necessary to draw up the 2026-2035 crisis management plan for the forest of the Château de Chantilly. A voluntary and resolutely proactive approach has been adopted in order to understand, anticipate, and adapt forest management to these new climatic challenges. It was in this context that the collective “Together, let’s save the Chantilly forest” was created, open to all and bringing together ONF foresters, INRAE researchers, scientific institutions, biodiversity stakeholders, local associations, and citizen volunteers. This collective has enabled significant fieldwork to be carried out: tree observations, sampling campaigns, soil analyses, and health monitoring, with a view to establishing as comprehensive an overview as possible. It is in this context that an open-air laboratory was designed, in order to preserve the forest, which is the Institut de France’s top priority.

The 2026-2035 crisis management plan

The crisis management plan for the forest of the Château de Chantilly was drawn up by the National Forestry Office (ONF) and approved by prefectural decree on December 31, 2025, under the forestry regime. It was reviewed by government departments, with a review by the Departmental Commission for Nature, Landscapes and Sites (CDNPS) of Oise and Val-d’Oise, as well as a Natura 2000 impact assessment. This document now constitutes the legal and operational framework for forest management.

This plan aims to mitigate the effects of climate change and is based on the following guidelines:

In accordance with the recommendations of the Academy of Sciences in its 2023 report on adapting French forests to climate change, the implementation, over 4,300 hectares, of mixed forestry with continuous cover: natural regeneration supplemented by the occasional introduction of species adapted to the future climate, and the abandonment of clear-cutting.

Individual monitoring of large oak trees, with harvesting conditional on the trees’ vital prognosis (once 50 to 75% of the branches are dead), in accordance with the DEPERIS protocol of the Department of Forest Health.

The creation of aging islands, currently covering 57.42 hectares, with a target of 190 hectares within +/- 30 years.

The establishment of a network of old trees with high potential for hosting bats, woodpeckers, and certain rare wood-eating insects (an average of three trees per hectare).

The development, in collaboration with biodiversity stakeholders, of a specific action plan aimed at preserving certain animal and plant species that are dependent on arid environments, which are now relicts but are likely to constitute the common biodiversity to be preserved in the coming decades.

In a context of significant climate change, the implementation of the plan is accompanied by the development of new monitoring indicators and enhanced scientific support, requiring dedicated resources. These guidelines are in line with the strategy defined by the Institut de France in the Chantilly 2030 document, consistent with the thinking of the Duke of Aumale.

See the 2026-2035 Crisis Management Plan for the Château de Chantilly Forest – ONF