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Conservation of forest genetic resources

The conservation of forest tree genetic resources should not be limited to "static" preservation of what seems to be in danger of disappearing. It is less important to fix the past than to prepare the future. In this evolutionary perspective, the "dynamic" conservation of genetic resources is advocated, which consists in favouring sexual reproduction and letting natural selection take place. The Commission on Forest Genetic Resources (CRGF) and the pan-European EUFORGEN (European Forest Genetic Resources Programme), in which we provide expertise, recommend a set of simple measures to preserve this diversity.

In support of the Ministry of Agriculture, we provide the technical secretariat of the CRGF and lead the national programme for the conservation of the genetic resources of the three native elm species that have fallen victim to the graphiosis epidemic.

This conservation programme for native elms includes:

-       a static component, based on a National Collection of clones from various French regions (441 clones),
-       a dynamic component, focused on the in situ conservation of:

• two populations of smooth elm (Ulmus laevis), implemented in the Garonne and Loire basins in partnership with the naturalists managing the sites concerned,
• a population of mountain elm (Ulmus glabra) in the Hautes-Pyrénées.

Collaboration with conservation areas (national nature reserves, botanical conservatories, biotope protection orders, etc.) was initiated at the end of 2019 to monitor smooth elm populations.

Fig2: National ex situ collection of native elms (Ulmus sp.) conserved on the INRAE site in Nogent/Vernisson. © INRAE
At the international level, we coordinated a European project on the ex situ conservation of elms in nine European Union countries, we collaborate in the EUFORGEN programme and we maintain the pan-European database of conservation units EUFGIS.

Selection of seed-bearing stands

Apart from certain fast-growing species (maritime pine, Douglas fir, larch, poplar, cherry, etc.) which have been the subject of genetic improvement programmes, a large proportion of the seedlings used in reforestation come from seeds harvested in the forest. In order to guarantee the traceability of the origin of these seeds and their genetic quality, the harvests must be carried out in accordance with the regulations (Forestry Code and European Directive), in areas defined by species, known as "regions of origin". For many species, these harvests are only authorised in stands duly registered in a national register, in areas defined by species called "regions of origin", after a visit by experts who ensure the overall quality of the trees (vigour and shape, health status, etc.).

Fig3: Example of regions of origin: map of maritime pine regions of origin (Pinus pinaster) © INRAE

Since the 1970s, Cemagref, then Irstea, then INRAE, has been responsible for the selection of seedbearing stands throughout France and for the management of the administrative and technical information related to them. In the context of climatic uncertainty, this current work is coupled with in-depth reflection on the nature and extent of the changes to be made in the selection criteria for seedbearing stands and in the advice on the use of the different planting material. To what extent should we encourage the "assisted migration" of more southerly provenances to areas of use where it is feared that the local provenance is no longer adapted to the climatic conditions predicted by climatologists for the second half of this century? As a result, our group is currently involved in the work of research groups on assisted migration, while at the same time engaging in dialogue with representatives of the sector (grain merchants, nurserymen, reforesters), decision-makers in charge of the public policies concerned (MAA and MTES) and our foreign counterparts.

Evaluation of improved forest varieties

France has a seed orchard programme, the design of which was entrusted to INRA and Irstea, then INRAE, and which is managed jointly by the ONF and the Vilmorin company. This programme mainly concerns fast-growing conifers.

Fig4: State hybridisation seed orchard of the Larch (Larix eurolepis) in Lavercantière (48).© INRAE

Fig5: Harvesting cones by climbing in the hybridisation larch orchard at Champ de la Ronce (Nogent/Vernisson). Climbers of the GIE Sitka. © INRAE

A programme to improve clonal poplar varieties for the production of plywood, light packaging and pulp is also being conducted.
Our work has contributed to the production of state seed orchards, which now significantly feed the forest seed and plant market.
The second stage, which began some 15 years ago, consists in checking the quality of varieties from seed orchards by means of forest tests to:

• quantify gains from known controls, evaluate site adaptation criteria
• (survival, health status, sensitivity to frost, drought), growth and wood quality indicators (shape, branching)

We manage a portfolio of evaluation tests of Douglas, larch, pine, spruce spread across the metropolitan territory. This activity is often carried out in collaboration with other organizations, including the ONF and the CNPPF. We coordinated the installation of an extensive testing network that provides information on the performance and conditions of use of the 8 French Douglas orchards in a changing climate context.

Fig6: Douglas Fir Orchard Assessment Network (Pseudotsuga menziesii) in 2020. © INRAE

As a member of the Poplar GIS, INRAE participates in the agronomic and health evaluation of cultivars in order to select the most interesting ones for the French population. We also contribute to the creation of new varieties combining productivity and tolerance to various diseases, especially foliar. These actions all aim to expand the range of varieties cultivated with a view to changing environments and the pressure of pathogens. We track more than 100 devices, for a total of about 30,000 trees to measure.

Fig7: Experimental device for evaluating poplar varieties, day of planting. © INRAE

Fig8: Circumference measurements in an experimental device for evaluating poplar varieties at 4 years.© INRAE

Statistics on the development of the national seed and plant market

Having annual data on seed harvests and on the production and sales of plants makes it possible to assess the adequacy of supply and demand, to follow trends and to have an indicator of the use of forest genetic resources. Each year, a briefing note compiling these data is produced and is available on the website of the Ministry of Agriculture. This short- and medium-term monitoring tool is particularly useful in the context of climate change.