Mémoire
Résumé : The Matang Mangrove Forest Reserve (MMFR) has been managed for charcoal productionsince 1902 and is subject to thinning and clearcutting cycles of around 30 years. Under thesupervision of the Forestry Department, concessions of mangrove land are allocated tocharcoal factory owners to manage thinning, clear-cutting and replanting activities.However, the condition of the concessions is unknown to the contractors until thesilvicultural activities start, as there is no a priori data available in terms of exploitablewood, which is heavily affected by the presence of lightening gaps. This thesis aims toemploy a combination of Earth Observation techniques including UAVs (unoccupied aerialvehicles or drones) and LANDSAT, as well as ground-based data to investigate how muchnatural or exploitable biomass is lost on average by lightning strikes, and the resultingfinancial consequences for the stakeholders involved in the management of theseconcessions. The results provided evidence of significant biomass loss, primarily due the lossof surface in productive zones, as consequence of lightning strikes that kills all the livebiomass. Additionally, there is as decrease in above-ground biomass (AGB) as the trees thatregenerate within lightning gaps are smaller than trees within managed forest. On the otherhand, recruitment (i.e., propagules, seedlings and saplings) inside gaps proved to be betterthan in closed canopy and could potentially alleviate loss of biomass after clear-cuttingevents. However, lightning gaps are not excluded from artificial thinning practices carried inthe MMFR, hindering the ecological potential of the former. Overall, the MMFR needs toaccount for biomass loss caused by lightning strikes, which significantly affects contractors,and allocate the same area in productive reserves, while acknowledging the potentialecological benefits of preserving these gaps from any silviculture practices.

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