Fire disturbances are increasing under global climate change and ecological transformations of forests are occurring. Specifically, shifts from productive closed-canopy feather moss forests to low-productivity open-canopy lichen (Cladonia spp.) woodlands have been observed in boreal forests of eastern Canada. It has been hypothesized that high severity of fires would be the cause of this change, but this is difficult to validate a posteriori on mature forest stands. Because charcoal properties are affected by fire severity, we have put forward the hypothesis that the amount and physicochemical properties of charcoal (C, N, H, O, ash, surface area) would be different and indicative of a greater fire severity for open-canopy forests compared to closed canopy ones. Our hypothesis was partly validated in that the amount of charcoal found on the ground of closed-canopy forests was greater than that of open-canopy forests. However, the physicochemical properties were not different, albeit a greater variability of charcoal properties for open canopy stands. These results do not allow us to fully validate or reject our hypothesis on the role of fire severity in the shift between open and closed canopy stands. However, they suggest that the variability in fire conditions as well as the amounts of charcoal produced are different between the two ecosystem types. Furthermore, considering the role that biochar may play in improving soil conditions and promoting vegetation restoration, our results suggest that charcoal may play a role in maintaining these two stable alternative ecosystem states.

Forest management can have major impacts on the dynamic of ecological communities, including shifts in reproduction and survival strategies in newly recruited individuals. This study aims to predict the probability of presence of saplings of various species in managed forests in the Sudanian domain of Senegal based on their functional traits. Data on functional traits and the main commercial and domestic uses of twenty high-socio-economic value species were collected, along with their presence-absence, in 12, 832 plots from twenty sites in Senegal's savannahs spanning four different types of forest management, including unmanaged forests, old managed forests, recently managed forests, and community reserve forests. Mixed logistic regression models were used to predict whether high-value species would be present in different forest management types, depending on their main uses, and regeneration, growth and reproduction functional traits. We hypothesised that forest management would favour species with more efficient colonising and competitive abilities, particularly at high levels of disturbance. Our findings demonstrated that unmanaged forests were more likely to host high-value species, regardless of their functional traits and main uses. These protected forests also hosted the greatest variety of regeneration functional traits, heights and uses. Old managed forests were more likely to host high-value species compared to recently managed and community reserve forests. Moreover, high-value species capable of vegetative regeneration and those with low maximum height were more likely to occur in all types of forests, but this trend was more pronounced under higher management and disturbance intensities. This study highlights that the availability of forest products can be optimised by encouraging management strategies that promote a diversity of functional traits rather than the selective harvesting of certain high-value species. Additionally, the temporal variation in the responses of tree species could be beneficial for forest management, with more diverse values of functional traits and more high-value species being present in older managed forests relative to newly managed forests. These results indicate that it is essential to promote forest resilience after management by protecting high-value species that have the potential to restore forest functional composition over time in managed forests.