Plant heritage and biodiversity: CMN cultivates the future

When we think of "heritage", we usually think of emblematic monuments and sites that bear witness to our history. But our plant heritage, often less well known, is just as rich, diverse and remarkable.

Abbey gardens and castle parks, rose gardens, orchards and historic kitchen gardens... The Centre des monuments nationaux preserves and promotes 83 exceptional parks and gardens throughout France.

These green spaces cover more than 3,300 hectares and tell the story of the sites, in the same way as their buildings. They are the result of past developments and the passing on of skills, techniques and know-how acquired over the centuries. They are also true ecological reservoirs and refuges for biodiversity.

But this green heritage is being undermined by the effects of climate change: flooding, rising water levels, drought, storms, etc. Biodiversity is being eroded in heritage parks and gardens. Flowering cycles are disrupted, invasive species proliferate and pollinators diminish.

CMN has long been committed to preserving its plant heritage, and is stepping up its efforts to meet these challenges. To this end, it is deploying a new conservation strategy designed to reconcile the heritage of its landscapes with environmental challenges.

Several restoration, redevelopment and replanting projects have been undertaken on emblematic sites. The aim is to restore the historical coherence of the landscapes, while adapting them to current ecological challenges.

These operations are restoring the splendour of green spaces that have been degraded by time and use. They also enable us to rediscover the old layout, reintroduce the original plant species and ornamental motifs, and plant more resistant species.

Current and future projects include

• work on the plant environment of the Grande Cascade on the Saint-Cloud national estate: replanting of tree lines and hedges, soil rehabilitation, etc;
• Replanting the boxwood borders of the bouquetier garden at the Château de Bouges;
• Restoration of the flowerbeds at Château de Montal: conservation of the original layout and planting, addition of flowerbeds planted with roses and other species to restore the original appearance of the embroidery;
• planting the courtyard of the tower house and ramparts of Aigues-Mortes...

Not all heritage green spaces are purely decorative: some of them are also cultural spaces.

Today, the CMN wishes to reactivate or strengthen the productive dimension of its parks and gardens, while respecting the historical identity of each site, such as :

• at the heart of the grounds of the Château de Voltaire in Ferney, where the kitchen garden in Voltaire's gardens is cultivated according to the principles of permaculture ;
• at the Château d'Azay-le-Rideau, where gardeners are working with a local association to preserve and develop old and sometimes forgotten varieties of vegetables from the region;
• at the Château de Bouges, where 35 hectares of meadows in the grounds and 4 hectares outside the estate are used to produce hay in a sustainable way.

The CMN relies on the strength of the collective to protect biodiversity on its sites in the long term. It is forging partnerships with specialised associations in order to gain a better understanding of the environments and species present.

These partnerships make it possible to carry out detailed environmental diagnoses and inventories, to set up scientific monitoring and to define management plans tailored to each site.

A wide variety of animal and plant species have been identified at a number of sites, including :

• the Château d'Angers, a veritable refuge or stopping-off place for birds, with 39 species listed, 18 of which breed on the site;
• the archaeological site of Glanum, with almost 100 animal species recorded;
• the Saint-Cloud estate, home to 53 bird species, 3 amphibian species, 2 reptile species and 6 mammal species;
• the Carnac alignments, where the latest inventory shows 167 plant species, including 3 nationally protected species and 1 regionally protected species.

Preserving biodiversity also means ensuring better, more environmentally-friendly land management. In line with the objectives of the ecological transition, the CMN has undertaken a transformation of its practices:

• introducing management plans to limit the use of drinking water for watering ;
• experimentation with vegetation, as at Abbey of Montmajour, to create a cool island;
• development of the garden plan, which integrates plants and water as an essential part of the heritage;
• deployment of eco-pasturing in certain national monuments, to limit the use of mechanical machinery and phytosanitary products for the upkeep of meadows and areas that are difficult to access;
• in-depth analysis of local biodiversity prior to any restoration work;
• creation of refuges for biodiversity, etc.

Each site deploys solutions tailored to its own specific constraints, drawing on the expertise of its teams and local stakeholders.

The conservation and enhancement of our plant heritage goes hand in hand with awareness-raising initiatives in monuments for all sections of the public.

Every year, the "Rendez-vous in the Gardens", an event organised by the Ministry of Culture, raises awareness of the richness of this heritage and the measures taken to protect it.

At the same time, numerous initiatives are deployed throughout the year in the monuments. Young and old alike can take part in guided tours, botanical initiations, educational workshops and other festive events on the theme of nature, to discover its role for our planet in general, and in monuments in particular.