MICROFOREST

Coordinating institution: INRAE 
Partner institutions:  CNRS | Cirad | Office National des Forêts
Project leaders: Benjamin Brachi (INRAE)
Project duration: 48 mois | 1 octobre 2025 → 30 septembre 2029

The field of evolutionary ecology, particularly the study of forest tree populations, has traditionally focused on identifying phenotypic and genetic differences among populations across species ranges. The aims of these studies are to understand how populations adapt to their local environments and to predict their adaptive potential in the face of global change. However, such approaches often overlook the extensive genetic diversity within forest tree populations, especially the dynamics of demography, genetic diversity, and natural selection within seedling cohorts.

In forest regeneration, the intensity of genetic drift and natural selection is influenced not only by seedling cohort sizes but also by the genetic diversity present within these cohorts. This diversity depends on the number of reproducing adults and the variability in their contributions to annual seedling cohorts. The overarching goal of MICROFOREST is to enhance our understanding of the demographic and evolutionary processes that shape genetic diversity within seedling cohorts in naturally regenerating forests. The specific objectives are twofold: (1) to analyze the distribution of parental contributions to these cohorts, and to estimate the intensity of genetic drift and natural selection within seedling cohorts, and (2) to assess the influence of forest management practices on these parameters. Addressing these objectives is critical for refining predictions of populations’ adaptive potential and maladaptation levels, often evaluated today using methods that do not consider genetic diversity within populations (e.g., genomic offset methods).

MICROFOREST focuses on four target species that are both economically and ecologically important, representing a range of climates and management practices: Quercus robur and petraea, Fagus sylvatica, Pinus pinaster, and Dicorynia guianensis. These species have been extensively studied by the participating research groups, offering valuable prior resources such as reference genomes and population resequencing or genotyping data.

The project is organized into four work packages (WPs). WP1 serves as a structuring component, focusing on communication with forest managers to ensure research addresses locally relevant questions and to disseminate findings through seminars and videos. WP2 is dedicated to monitoring annual seedling abundance and survival in forest regeneration and analyzing the neutral and functional genetic composition of seedling cohorts and potential parents. This work involves high-throughput genotyping of over 12,000 samples across the four species, with the aim of comparing sites under different management modalities in terms of seedling cohort demography, micro-environmental selection in the forest understory, and variance in parental contributions. WP3 is focused on developing null models to contextualize field data and simulate the effects of management practices at landscape and regional scales. This modeling work will provide actionable recommendations for forest managers in collaboration with WP1. Finally, WP0 is dedicated to overall project coordination.

The knowledge generated in MICROFOREST will support the development of management strategies that maintain and leverage within-population genetic diversity, thereby increasing the likelihood of generating genetic combinations suited to future climates. Such strategies represent low-risk, nature-based solutions that strengthen forest resilience and sustainability by harnessing the immense genetic diversity already present in forest tree populations, offering powerful alternatives to assisted migration and assisted gene flow.