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Road networks are growing globally, especially in tropical countries, allowing human access to remaining Intact Forest Landscapes (IFL) that are refuges for biodiversity and provide globally important ecosystem services. Selective logging is now widespread in tropical forests, acting as one of the main drivers of road network expansion, with logging roads often being considered door-openers and conduits for human impacts. The protection of road-free IFL is high on the biodiversity conservation agenda, a challenge for logging concessions certified by the Forest Stewardship Council (FSC). However, the impacts of logging roads can be highly variable depending on road use and management. In a logging-hot-spot of the Congo Basin, only 12% of all roads were permanently open, with all others becoming quickly revegetated and inaccessible. Taking limited road persistence into account, we analyzed how road networks in FSC certified concessions affected IFL. We followed the spatial and temporal dynamics of logging roads, comparing roadless space in certified and non-certified logging concessions inside and outside areas declared as IFL in the year 2000. We found that roadless space decreased rapidly in IFL, notwithstanding FSC certification, highlighting the urgent need for measures to safeguard ecological corridors between protected areas and remaining intact forests. Logging concession certification by FSC might play a key role in conserving forest connectivity by strategic road network planning. Forest management should make the preservation of large connected forest areas a top priority by effectively monitoring - and limiting - the occupation of space by roads that are accessible at the same time. Given the strong dynamics between the impacts of different types of roads, we challenge the static definition of IFL based on a buffer around any road ever detected.

During the past 25 years, forest laws in Central African countries have undergone major changes. Management plans were made mandatory: nearly 19 million hectares of timber concessions (38% of total granted concessions) were subject to a management plan in 2013 and the dynamics is currently underway. The management plan is based on a set of technical and scientific studies, including statistical surveys (management inventories) covering the whole concession and taking into account all timber species, large mammals and the main non timber forest products. These inventories allow, at concession level, to characterize ecosystems and to assess the forest conservation values, through floristic and faunal biodiversity indicators and by taking into account threats to the forest ecosystems, especially anthropogenic ones. Such management inventories are used especially for planning and forecasting harvests, while minimising environmental impacts on the forest structure and functioning, and retaining regeneration capacities of the timber species and the forest ecosystems. The knowledge gained on specific and ecosystemic biodiversity helps to define management rules to ensure the sustainability of different timber species' populations, noticeably the exploited ones. It is also used to design areas within the concessions were exploitation will not take place due to conservation interest (most biodiversity-rich areas, protection of rare or endangered species...). Such so-called “conservation series” therefore complement the protected areas network. Well-managed forest concessions can help conserve the regional forest ecosystems and maintain essential functions that they provide. However, management plans were up to now designed at the concession scale. Data acquired in forest concessions also significantly contribute to improve knowledge of the forest ecosystems and their functioning at the regional level. Using this data, the CoForChange Project (http://www.coforchange.eu) issued a map of the forest ecosystems developed in the "Sangha River Interval" region. This project suggested that those forest ecosystems could react differently to disturbance, and could need an adaptation of management methods to each ecosystem. Based on forest inventories, other initiatives are underway to map the forest types and the biomass stock at the scale of Central Africa, and might be of particular interest for policy decisions on forest ecosystems. (Texte intégral)

Background: The tropical forests in general, and those of Central Africa in particular, stand at the cross-road. The combined and interacting effects of land-use change, resource extraction, defaunation, fire, fragmentation and climate change are pushing these ecosystems towards critical points where transitions to altered states will happen. The future of these forests depends on our capacity to understand and anticipate these transitions, and to identify these states the forest ecosystems are likely to take. Yet, to date, there was not a unified model that presented the best available knowledge on the forest dynamics of the regions. The field is highly fragmented and we lack a general overview. Method: We propose here a general unified model of forest dynamics in Central Africa. This model represents the best available knowledge on the topic and is the result of a collaborative effort based on expert knowledge and an analysis of the literature. We built it using methods issued from the fields of facilitation, participatory modelling and team science. Result: Our model identifies the main forest types present in the area, the dynamic links and possible transitions between them and the potential impacts of environmental factors - climate, soil, large mammals - and human factors - logging, fire, clearings. It provides a description of these forest types and allows the layman to grasp the general dynamics at play in the region. For those willing to deepen their understanding, we provide all the necessary literature leads to guide them in their discovery of the topic. Conclusion: Our aim is to propose as an easy to access gateway for those needing to take decisions on how to manage the forests of Central Africa in the coming decades. It sums up our current understanding of the system, helps chart knowledge gaps and highlight avenues for future research, serving as basis for discussions. An accepted common understanding of the dynamics of these forests will be solid foundation for alternative modes of management to emerge, we hope it will foster dialog between key stakeholders, and generate better informed decisions, more resilient to surprises. (Texte intégral)