## 4 Discussion
Nevertheless, our findings also highlight that, if species range might be totally or partly preserved, there are large uncertainties on future biomass stocks. In absence of a long-term CO\({}_{2}\) fertilization effect, CARAIB projects significant dieback (i.e., amplitude of biomass loss two to three times the biomass variability calculated for the reference period) over all the conserved distribution. Considering the species ensemble, it means an average biomass loss of \(-\)21.2% under RCP4.5 and \(-\)34.5% under RCP8.5. Despite a mean biomass increase of 12.2%, assuming a positive feedback of increasing CO\({}_{2}\) does not prevent tree dieback both at the outer limits and in the core of the preserved distributions. This shows the competing effects that climate change and CO\({}_{2}\) fertilization might have [109; 110]. This zoom on 12 individual species confirms that individual species respond differently to new climatic and atmospheric conditions, which may induce a new dynamics of competition in the ecosystem. For example, whereas the model projects under RCP8.5 CO\({}_{2}\) [var] configuration that mean biomass might increase by as much as 28% for _Elaesis guineensis_, it simulates unchanged biomass stock for _Guibourtia demeusei_ and _Pericopsis elata_. Under RCP8.5 CO\({}_{2}\)[330] configuration, the three deciduous species (_Ceiba pentandra_, _Lophira alata_ and _Pericopsis elata_) of our set are projected to experience the strongest dieback (around 50% of biomass loss over the current distribution). The impact differs also significantly between smaller study areas. For instance, over the WWF Lake Tele-Lake Tumba Landscape in DR Congo, a forest-savanna mosaic with strong spatial variation in forest biomass [111], the currently present species would not profit off the new conditions; they would sustain but not amplify current production rates. On the contrary, previously (nearly) absent species would appear and amplify their production rates exponentially. Such a species turnover would not be a favorable situation since those species not necessarily have the same role in the ecosystem nor provide the same services. Today, countryside way of life still partly relies on conventional plant uses. Finally, we want to notice that the traits values used in this study are measured under current climate conditions and that, under influence of climate change, acclimation of these traits may occur. For example, [PERSON] et al. [112] highlight that rooting depth could be a major determinant of how tropical trees will fare during extreme droughts. Assumptions on the physiological responses of species to new climatic conditions thus remain necessary [49]. These results must also be analyzed keeping in mind the absence of anthropogenic actions and species dispersal/migration limitations. Synergistic interactions and feedbacks of clearing and forest fragmentation certainly have major implications for the vulnerability of forests to climate change. While the precise sensitivity is not known, human activities appear to increase the climate sensitivity of forest areas that are not directly affected by these activities, causing feedbacks on global and regional climates [30; 102]. At the same time, [PERSON] et al. [113] showed that appropriate ecosystem management can mitigate climate change impacts on vegetation and delay or avoid undesired vegetation shifts. We thus emphasize the potential gain of studies that examine human and climate pressures simultaneously (e.g., [114]). The development of approaches that integrate two spatial and dynamic models, one simulating vegetation and the other simulating land use by human agents (multi-agent model), should be encouraged to expand our knowledge of the complex interactions between human beings and ecosystems. The call for the integration of perspectives of natural sciences with those of social sciences [115; 116] is then obvious. The question also arises whether the species would be able to migrate in order to reach newly suitable potential areas.