Fig. 1

Diagram showing how hypothetical mixed stands are either transient in the competitive exclusion zone or stable in the coexistence zone in the space of fitness equivalence and strength of stabilisation and the various potential effects of management on these stands. We also present hypothetical management interventions that can move (dashed arrows) a transient stand (A) into the coexistence zone by either changing the fitness equivalence (A′, for instance by cutting preferentially the most competitive species) or the strength of stabilisation (A′′, for instance by preferentially cutting the most common species) or both (A′′′, for instance by applying gap silviculture adapted to species requirements). But management interventions can also move a stable coexisting mixed stand into the competitive exclusion zone (pathway B–B′, for instance by harvesting preferentially one of the species) or may not be efficient enough to stabilise a mixed stand (pathway C–C′). In addition, management interventions can also impact the positive effect of biodiversity on ecosystems’ function (for instance the overyielding), either decreasing it (A′) or increasing it (C′). In general, depending on the species involved, management interventions can affect both stabilising and equalising mechanisms, as illustrated by moving from mixture A to A′′, but with different intensities. It is important to point out that the two dimensions of the diagram are difficult to quantify and to tease apart in field studies