Post-fire forest restoration in the humid tropics: A synthesis of available strategies and knowledge gaps for effective restoration.

Humid tropical forests are increasingly exposed to devastating wildfires. Major efforts are needed to prevent fire-related tipping points and to enable the effective recovery of fire-affected areas. Here, we provide a synthesis of the most common forest restoration strategies, thereby focusing on post-fire forest dynamics in the humid tropics. A variety of restoration strategies can be adopted in restoring humid tropical forests, including natural regeneration, assisted natural regeneration (i.e. fire breaks, weed control, erosion control, topsoil replacement, peatland rewetting), enrichment planting (i.e. planting nursery-raised seedlings, direct seeding) and commercial restoration (i.e. plantation forests, agroforestry). Our analysis shows that while natural regeneration can be effective under favourable ecological conditions, humid tropical forests are often ill-adapted to fire, and therefore less likely to recover unassisted after a wildfire event. Active restoration practices may be more effective, but can be costly and challenging to implement. We also identify gaps in knowledge needed for effective restoration of humid tropical forests after fire, hereby taking into account the ecosystems and socio-economic conditions in which these fires occur. We suggest to incorporate fire severity in future studies, to better understand and predict post-fire ecosystem responses. In addition, as fire poses a recurring and intensifying threat throughout the recovery process, more emphasis should be placed on post-restoration management and the prevention of fire throughout the different phases of the restoration process. Furthermore, as tropical wildfires are increasing in scale, establishing collaborative capacity and setting priorities for efficient resource allocation should become a major priority for restoration practitioners in the humid tropics. Finally, as global fire regimes are changing and expected to intensify in the context of climate change, land use and land cover change, we suggest to put continuous effort into fire monitoring and modelling to inform the development of effective restoration strategies in the long-run.