[Managing mixed forest stands : bridging the gap between silviculture and ecological theory]

In this article, we illustrate the value of combining ecological theory and silviculture through the example of continuous cover forestry in mixed stands and the use of a forest dynamics model that addresses research questions in ecology and biogeography (MATREEX). In a context where diversification is a strategy promoted for the adaptation of forests to climate change, we explore how different species coexistence mechanisms (negative frequency dependence, relative nonlinearity, recruitment-survival trade-off) can be translated into silvicultural actions and test their effectiveness in terms of species coexistence. Our study focuses on two types of mixed stands known to be difficult to manage between sessile oak (Quercus petraea (Matt.) Liebl.) and common beech (Fagus sylvatica L.), on the one hand, and silver fir (Abies alba Mill.) and Scots pine (Pinus sylvestris L.), on the other hand.We show that preferential selection of the most abundant species (negative frequency dependence), which is easy to implement and already used in forest management, is very effective in favouring the least competitive species in the stand. The other mechanisms tested have only a limited influence on species proportions. Although these results must be interpreted with caution, taking into account the limitations of the model used, they provide initial findings that can be explored further using other approaches and give rise to hypotheses that can be tested in situ.