Tree rings depend on seasonal variation in radial tree growth. Where they can be identified, their interannual variation may reflect climate variability. Compared to its use in temperate and boreal regions, tree-ring analysis has been less applied in tropical Africa, with weaker seasonality. Daniellia oliveri often forms the tallest trees in agroforestry parklands of the Sudanian savanna zone of Mali but its growth response to climate (rainfall, temperature) variability has not been documented. We analyzed six stem disks of D. oliveri and used standard dendrochronological methods to process the samples. Contrary to earlier literature likely based on more humid parts of the species distribution range, D. oliveri formed distinct growth ring boundaries in our study area. The mean annual radial growth was 2.73 ± 0.56 mm. All measured tree-ring series were successfully cross-dated with a GLK (Gleichläufigkeit) value of 76.3 ± 5.6. The final tree-ring chronology covers the period 1909-2021. After removing age-related growth trends, the tree-ring width index showed a significant relationship with records of annual rainfall (r2 = 0.46, n = 100 years, p < 0.001). The relationship between wet-season (June to September) precipitation and the residual chronology was slightly higher (r2 = 0.50, n = 100 years, p < 0.001). However, no significant correlation was found for temperature. These results imply that D. oliveri can be successfully used for dendrochronological studies with relevance for the management and restoration of the ecosystems in the Sudanian zone of West Africa, where long-term rainfall records are scarce.
Tag: Agroforestry
Climate-growth relationships of Daniellia oliveri (Rolfe) Hutch. & Dalziel in the Sudanian zone of Mali, West Africa
Tree rings depend on seasonal variation in radial tree growth. Where they can be identified, their interannual variation may reflect climate variability. Compared to its use in temperate and boreal regions, tree-ring analysis has been less applied in tropical Africa, with weaker seasonality. Daniellia oliveri often forms the tallest trees in agroforestry parklands of the Sudanian savanna zone of Mali but its growth response to climate (rainfall, temperature) variability has not been documented. We analyzed six stem disks of D. oliveri and used standard dendrochronological methods to process the samples. Contrary to earlier literature likely based on more humid parts of the species distribution range, D. oliveri formed distinct growth ring boundaries in our study area. The mean annual radial growth was 2.73 ± 0.56 mm. All measured tree-ring series were successfully cross-dated with a GLK (Gleichläufigkeit) value of 76.3 ± 5.6. The final tree-ring chronology covers the period 1909-2021. After removing age-related growth trends, the tree-ring width index showed a significant relationship with records of annual rainfall (r2 = 0.46, n = 100 years, p < 0.001). The relationship between wet-season (June to September) precipitation and the residual chronology was slightly higher (r2 = 0.50, n = 100 years, p < 0.001). However, no significant correlation was found for temperature. These results imply that D. oliveri can be successfully used for dendrochronological studies with relevance for the management and restoration of the ecosystems in the Sudanian zone of West Africa, where long-term rainfall records are scarce.
Climate-growth relationships of Daniellia oliveri (Rolfe) Hutch. & Dalziel in the Sudanian zone of Mali, West Africa
Tree rings depend on seasonal variation in radial tree growth. Where they can be identified, their interannual variation may reflect climate variability. Compared to its use in temperate and boreal regions, tree-ring analysis has been less applied in tropical Africa, with weaker seasonality. Daniellia oliveri often forms the tallest trees in agroforestry parklands of the Sudanian savanna zone of Mali but its growth response to climate (rainfall, temperature) variability has not been documented. We analyzed six stem disks of D. oliveri and used standard dendrochronological methods to process the samples. Contrary to earlier literature likely based on more humid parts of the species distribution range, D. oliveri formed distinct growth ring boundaries in our study area. The mean annual radial growth was 2.73 ± 0.56 mm. All measured tree-ring series were successfully cross-dated with a GLK (Gleichläufigkeit) value of 76.3 ± 5.6. The final tree-ring chronology covers the period 1909-2021. After removing age-related growth trends, the tree-ring width index showed a significant relationship with records of annual rainfall (r2 = 0.46, n = 100 years, p < 0.001). The relationship between wet-season (June to September) precipitation and the residual chronology was slightly higher (r2 = 0.50, n = 100 years, p < 0.001). However, no significant correlation was found for temperature. These results imply that D. oliveri can be successfully used for dendrochronological studies with relevance for the management and restoration of the ecosystems in the Sudanian zone of West Africa, where long-term rainfall records are scarce.
Scaling & Enhancing Restoration Impact Through Gender Transformative Approaches
Regreening Africa enhances resilience in the Sahel and Horn of Africa by addressing climate change, land degradation, and food insecurity. Through a broad partnership network, the initiative scales context-appropriate land restoration by integrating trees and sustainable practices into farming and pastoral systems. Phase II expands efforts in Somalia, Ethiopia, Senegal, Nigeria, Ghana, Mali, and Niger, focusing on systems scaling for transformative change. Building on Phase I, this phase promotes agroforestry, FMNR, soil and water conservation, soil health improvement, grazing management, and energy-efficient cookstoves to boost land productivity and resilience, particularly in rangeland and mixed landscapes.
Review: Improving the enabling environment to strengthen Kenya’s tree seed and seedling systems
Key Recommendations
- Define and regulate tree seed quality by explicitly incorporating genetic, physical and physiological quality and climate adaptation to planting environments, recognizing that tree seed quality cannot be regulated in the same way as crop seed.
- Formally define and register all tree seed sources, including natural vegetation, farmland, plantations, and seed orchards, using source-specific guidelines that ensure genetic quality.
- Strengthen the use and conservation of native tree species by identifying and protecting seed sources for native species, and supporting incentives that encourage landowners, nurseries, and restoration projects to plant and use native trees.
- Develop clearer and more appropriate rules for different tree species and planting purposes by reviewing and adapting regulations to better distinguish between native and exotic species, and between trees grown for commercial forestry and those planted for environmental restoration or ecosystem services.
- Establish an inclusive certification and registration pathway by introducing an affordable Quality Declared Seed system for tree seed, allowing small-scale tree seed collectors to gradually enter the formal system while adhering to quality standards.
- Clarify and align institutional roles and responsibilities, with Kenya Plant Health Inspectorate Service as the certifying authority, Kenya Forestry Research Institute (KEFRI) providing scientific research, technical leadership, training and seed source approval, and Kenya Forest Service (KFS) integrating seed source management into forest governance.
- Recognize and operationalize seed source custodians including communities and Community Forest Associations to manage, protect and benefit from documented seed sources, supported through collaboration between KEFRI and KFS.
- Improve tree planting and forest management outcomes by developing species-specific planting zones and site-matching guidelines, and by registering nurseries to strengthen links between seed supply, seedling production and planting demand.
- Invest in sector-wide information and communication systems that connect seed collectors, nurseries and tree planters; disseminate seed source and planting zone information; and support informed participation across the seed–seedling–planting continuum.
- Right tree, right place, right purpose: Increase knowledge and capacity building to ensure that quality tree seed is planted in the right place for the right purpose for improved livelihoods and climate resilient ecological restoration.
Review: Improving the enabling environment to strengthen Rwanda’s tree seed and seedling systems
Key Recommendations
- Update and implement the Forestry Reproductive Materials Guidelines (MoE 2018) and the Tree Reproductive Materials Strategy (MINILAF 2018) to improve identification, documentation, and protection of native tree seed sources.
- Expand and identify a national network of certified tree seed sources managed by recognized seed source custodians.
- Strengthen access to and use of native tree species by conducting phenology studies and streamlining permit processes in protected areas for tree seed collectors.
- Develop and widely disseminate species-specific seed zoning and planting maps to guide all tree planting decisions.
- Introduce and enforce national nursery standards requiring full traceability of seed origin throughout seedling production.
- Ensure farmers and extension agents have clear, accessible agroforestry guidance tailored to local conditions and agency mandates.
- Shift the National Tree Seed Centre (NTSC) from sole tree seed production toward a regulatory and supportive role while expanding trained tree seed cooperatives and NTSC sub-centres.
- Clarify and communicate the roles and responsibilities of all actors, formally recognizing seed source custodians within the delivery system.
Sectoral assessment summary: Advancing an effective tree seed and seedling system in Kenya
This sectoral assessment provides a baseline analysis of Kenya’s tree seed and seedling systems, with a focus on how seed systems can better support FLR and agroforestry that takes into account ecological principles, first and foremost by basing species choice on the map of potential natural vegetation of Kenya, when restoring natural vegetation. This brief identifies structural constraints, highlights the essential role of decentralized actors, and outlines practical recommendations to strengthen coordination, genetic quality and effectiveness across Kenya’s tree seed and seedling systems.
Sectoral assessment summary: Advancing an effective tree seed and seedling system in Rwanda
This sector assessment provides a baseline analysis of quality tree seed sources and tree seed and seedling distribution in Rwanda, identifying key challenges in access, distribution, and management, and highlighting opportunities to strengthen sector coordination in support of national restoration targets.
Prunus africana: From extractive trade to a regenerative medicinal tree-powered bioeconomy in Africa
- Prunus africana (African cherry) is a highly valuable medicinal tree species distributed across more than 22 African countries where it provides a wide variety of ecosystem services including biodiversity conservation, watershed protection, carbon sequestration in montane forest ecosystems, as well as many products of socioeconomic interest collected from its bark, roots, wood and leaves.
- The anti-inflammatory and anti-androgenic properties of its bark extract are used in traditional and conventional medicine for treating benign prostatic hyperplasia (BPH), prostate cancer and other urinary ailments affecting older men worldwide. Moreover, recent advances in phytochemistry have revealed novel bioactive fractions with potential applications in gastrointestinal oncology, dermatological regeneration, cosmeceuticals and functional food preservatives, thereby broadening opportunities for P. africana-based biopharmaceutical development.
- Europe remains the largest importer of P. africana bark products, while Asia is rapidly expanding its pharmaceutical and herbal integration markets. North America maintains stable demand through supplements and over-the-counter prostate formulations. African markets for P. africana based-medicinal and pharmaceutical products remain very poorly developed.
- To align with the African Union strategy for driving circular nature-based industrialization, some African countries, including South Africa, Ghana, Nigeria, Cameroon, Uganda and Kenya are promoting medicinal herbal-based bioeconomy frameworks and biopharmaceutical companies. Such developments are expected to catalyse the African perspectives on a P. africana powered bioeconomy.
- The global market for P. africana products is projected to grow from USD 150 million in 2024 to USD 250 million by 2033, driven by rising demand for herbal medicines and aging populations. The projected innovations in its medicinal applications will certainly add to the current growing trend.
- Due to international trade regulations imposed by the inclusion of the species under CITES Appendix II since 1995, Cameroon has contributed to the development of sustainability measures through institutionalization of Non-Detriment Findings (NDFs), supported by scientific evidence on improved bark harvesting techniques and standards, existing harvestable tree potential, and inclusive management plans. Moreover, domestication and integration into agroforestry, restoration and climate agendas, offer an opportunity to move from a compliance-driven model to a genuinely regenerative bioeconomy.
- The trend in global dry bark exports shows distinct phases tied to trade traffic and regulations as well as CITES quota realignments, with Rwanda, Cameroon, Tanzania, Democratic Republic of the Congo (DRC) and Burundi supporting nearly 90 percent of the global bark export market.
- Despite persistent challenges, including weak governance, inequitable benefit sharing, climate change, habitat degradation, informal trade and limited local processing capacity, P. africana could become a flagship species for Africa’s regenerative circular bioeconomy if backed by equitable governance, restoration efforts, innovation-driven biopharmaceutical development and community-centred sustainable management.
Climate-growth relationships of Daniellia oliveri (Rolfe) Hutch. & Dalziel in the Sudanian zone of Mali, West Africa
Tree rings depend on seasonal variation in radial tree growth. Where they can be identified, their interannual variation may reflect climate variability. Compared to its use in temperate and boreal regions, tree-ring analysis has been less applied in tropical Africa, with weaker seasonality. Daniellia oliveri often forms the tallest trees in agroforestry parklands of the Sudanian savanna zone of Mali but its growth response to climate (rainfall, temperature) variability has not been documented. We analyzed six stem disks of D. oliveri and used standard dendrochronological methods to process the samples. Contrary to earlier literature likely based on more humid parts of the species distribution range, D. oliveri formed distinct growth ring boundaries in our study area. The mean annual radial growth was 2.73 ± 0.56 mm. All measured tree-ring series were successfully cross-dated with a GLK (Gleichläufigkeit) value of 76.3 ± 5.6. The final tree-ring chronology covers the period 1909-2021. After removing age-related growth trends, the tree-ring width index showed a significant relationship with records of annual rainfall (r2 = 0.46, n = 100 years, p < 0.001). The relationship between wet-season (June to September) precipitation and the residual chronology was slightly higher (r2 = 0.50, n = 100 years, p < 0.001). However, no significant correlation was found for temperature. These results imply that D. oliveri can be successfully used for dendrochronological studies with relevance for the management and restoration of the ecosystems in the Sudanian zone of West Africa, where long-term rainfall records are scarce.