Land use change and local forest dynamics in the forest-savannah boundary in central cameroon
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The document discusses the impact of local forestry practices on landscapes and land-use changes in the forest-savannah boundary of central Cameroon, highlighting the significant human influence on these ecosystems. It addresses the historical context of afforestation, local perceptions, and strategies for managing changes caused by invasive species like Chromolaena odorata. The need for an analysis of biocultural interactions to understand local responses to ecological changes is emphasized.
Land use change and local forest dynamics in the forest-savannah boundary in central cameroon
- 1. Taking stock of smallholders and community forestry Session 13 Impact of local forestry practices on landscapes Land-use change and local forest dynamics in the forest-savannah boundary in Central Cameroon
- 2. Let’s go to Central Cameroon
- 3. Fairly recent introgression of forest onto savannah Humans are hardly responsible for past bioclimatic events… … But they have co-influenced the impact of such events on the environment… … Humans are becoming a major driving force in the dynamics of ecosystems Ongoing afforestation on African forest margins Attested throughout Western and Central Africa Bioclimatic origin of this phenomenon that started 1,000 years BP Local perceptions and attitudes vis-à-vis spontaneous afforestation are poorly documented
- 4. Multidisciplinary evidence of this extensive phenomenon • Phytogeography • Botany • Phytosociology • Remote sensing • Pedology • Dendrochronology • Isotopic biochemistry • Sedimentology • Phytolites • Palynology • Ecology • Archeology • Anthropology
- 5. Forest-savannah ecotone • Rich ecosystem - Diversified mosaic - Forest plants and animals meet with savannah plants and animals - Life forms specific to the ecotone • Dynamic ecosystem - Afforestation: 1 to 3 meters per year - Changes perceptible in just a few years - Ideal conditions to question adaptation to change
- 6. Ecological heterogeneity of the ecotone forest/savannah ecotone in the forest/savannah ecotone in the southern area northern area
- 7. Tikar… and Bedzan • Warlike and conquering stratified society • Originally cereal cultivators • Brought their ecology with them • Sorghum progressively replaced by maize • “Absorption” of populations met along migration • Initiated into forest by Bedzan Pygmies
- 8. Forest swiddeners and savannah cultivators Intercropped swidden under forest Monocultural (cassava) field in the savannah
- 9. Non agricultural activities hunting fishing gathering
- 10. Afforestation between 1950 and 1989 Sectors of faster afforestation: former village settlements
- 11. Accelerated afforestation near residential sites Villages were built right up against the forest edge
- 12. Accelerated afforestation near residential sites Temporary swidden camps
- 13. Accelerated afforestation near residential sites Seasonal fishing camps
- 14. Accelerated afforestation near residential sites In 35 years
- 15. Local strategies to control afforestation Fragmented swidden area Single swidden area fast afforestation slowed afforestation
- 16. Local strategies to control afforestation Selective tree cutting by forest swiddeners
- 17. Local strategies to control afforestation Seed rain and nucleation
- 18. Local strategies to control afforestation 1970s: Permanent agroforest belt as a fence against afforestation Coffee agroforest
- 19. Local strategies to control afforestation Agroforest trees as safety net Ictyotoxic bark of Albizia coriaria Medicinal bark of Enantia chloranta Storage of cola nuts in termites’ nests
- 20. Local strategies to control afforestation 1980s: invasion by Chromolaena odorata (Asteraceae) Pan-tropical invasive shrub Good for agronomy • Voluntarily introduced as a cover crop • Improves soil structure (stops the leaching of mineral elements, increases the depth of the humus stratum, reduces soil acidity) • Green manure • Nematicide properties Bad for ecology • Compromises forest regeneration • The African variegated grasshopper (Zonocerus variegatus, Orthoptera, Pyrgomorphidae)
- 21. Local strategies to control afforestation Early burning of savannahs Chromolaena facilitates afforestation Suffrutescent plant: architecture smothers fire and protects tree seedlings of the forest edge Abundant faunal circulation underneath (rodents) Early burned savannahs
- 22. Local strategies to control afforestation Delayed burning of fallows Exhausting clearing of young fallows invaded by Chromolaena
- 23. Local strategies to control afforestation Delayed burning of fallows Chromolaena compromises afforestation High caloric return of Chromolaena burning
- 24. Local strategies to control afforestation Effect of Chromolaena on the fallowing rotation • No more forest regrowth • Fallowing period reduced to 5 years
- 25. Local strategies to control afforestation Community farming activities and mutual aid Increased man-days per hectare Socio-political system of savannah farmers more adapted to Chromolaena
- 26. In brief 1980s Invasion by Chromolaena odorata
- 27. Where do we go from here… … well, let’s go back to there! • Coupled human-nature shaping of ecosystems • Analysis of biocultural interactions needed to catch local understanding and influence of ecosystem dynamics (socioecological systems) • Local rationality differs from the scientific and conservationist views • Indigenous peoples are not de facto “conservationists”, but may elaborate adaptive responses that are environmental-friendly • “Conservationist” does not mean “conservative”. Adaptive responses may be stimulated by external factors (cash crop plantations ; invasive shrub) • Innovative adoptions depend on socio-political features of the considered community
- 28. Thank you for your attention!