| The Mayombe tropical forests of central Africa are home to diverse wildlife species, provide vital ecosystem services of local and global importance,and support the livelihood of millions of human populations.These forest ecosystems are experiencing dramatic changes that have led to deforestation and forest degradation.However,there are still knowledge gaps concerning the spatial pattern of land use changes,the nature of factors that induce these land use changes,and how these changes affect biodiversity and forest ecosystem services to local communities.These information are useful in guiding the decision-making process on land planning for biodiversity conservation and sustainable development of local communities.The present study aims at advancing the current understanding by addressing these knowledge gaps with a case study within the Luki biosphere reserve（the biggest remnant of the Mayombe tropical forest in the Democratic Republic of Congo）under dramatic land use/land cover changes.Thus,a multidisciplinary approach integrating remote-sensing and geoinformational techniques,social and ecological data was used to address these knowledge gaps.A multi-date classification of Landsat TM satellite images from 1987,ETM+from 2002,OLIR TIRS from 2020 was used to quantify the spatiotemporal land use changes within the Luki biosphere reserve,and its effects on land-surface temperature variations over the last decades.Thereafter,a qualitative and participatory approach,through social surveys was used to identify and examine the drivers of land use/land cover changes,as well as the effect of land use changes on the availability of the provisionning ecosystem services.The study further examined the impact of land use/land cover change on tree biodiversity and carbon storage by conducting biodiversity surveys within forest lands under different level of human disturbance intensities.Finally,the research used both machine learning and Markovian chain to predict the future land use/land cover change for the next three decades,based on the current trends dominated mainly by the increasing agricultural production.The results showed that between 1987 and 2020,primary forest declined from 87.59% to 72.02%,representing an annual lost in area estimated at 141.53 hectares;while farmland increased from 4.81%to 16.5%,with an annual gain in area estimated at 115.31 hectares.Other land use/land cover types such as savannah,secondary forest and built-up areas have experienced a positive change with an annual gain in area estimated at 2.54,34.38,and 1.99hectares,respectively.Similar trends of change have been observed in primary forest and farmland,based on the prediction results of land use/land cover change for the next three decades;while the secondary forest will decrease by 16.58%.However,the study revealed that these changes have been mainly induced by the expansion of unsustainable agricultural activities,charcoal production and artisanal logging.Socioeconomic factors such as education,employment,length of residency,age,gender,and household size,significantly influenced the involvement of households in socioeconomic activities that induce land use change within the study area.Consequently,these changes have significantly decreased the availability of the ecosystem services over the years.Based on the perception of local communities,land use changes have resulted in the decrease in bush meat,mushroom,honey,wild fruits,wild vegetables,medicinal plants,caterpillars,and wood species,over years.Also,the results revealed that tree species richness,abundance and diversity decrease with increasing forest utilisation.The carbon storage was also significantly affected by the current land use change,varying from 14.16±4.09 Mg C ha-1 in high utilization regime,56.04±13.96 Mg C ha-1 in moderate utilization regime,to 124.35±14.88 Mg C ha-1 in low utilization regime,showing a decreasing trend with human disturbances.However,the results have shown that the Mayombe forests have the potential to recover after human disturbances.After 10 and 20 years of abandonment,the carbon storage increased up to 23.96±5.19 and 42.16±8.49 Mg C ha-1 in high utilization regime,while it increased up to 65.21±15.67 Mg C ha-1 and 83.20±15.09 Mg C ha-1in moderate utilization regime.Thus,this provides clear evidence that forest fallow lands under both high and moderate utilization can be managed under the REDD+initiative to facilitate the recovery process of carbon storage,biodiversity,and other various ecosystem services within these lands.Similarly,the study’s findings observed an alarming increase in land surface temperature within the study area,as a result of land use change.From 2002 to 2020,in all newly converted areas,mainly the conversion of primary and secondary forest to other land use types;an increasing trend of the land surface temperature has been observed which directly contributing to global warming.To cope with the adverse impacts of the increase in land surface temperature towards agricultural activities,farmers used various strategies including the adjusting sowing dates,the selling of forest products and livestock,and soil management.Finally,the present research draws together these findings to highlight current challenges to sustainable land management within the Mayombe tropical forest,and the implication of these findings in the implementation of sustainable forest management strategies for biodiversity conservation,sustainable development of local communities;and climate change mitigation strategies within the Mayombe forest.The results obtained in this thesis will not only improve the management of the Mayombe forest ecosystems for biodiversity conservation and sustainable development of local communities,but will also allow to feed the discussions and documents relating to the REDD+strategy in the Democratic Republic of Congo. |
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