ATRN Scientific goals

Many livelihoods, economic activities and energy sources in Sub-Saharan Africa (SSA) are largely dependent on climate-sensitive natural resources. The climate crisis is increasing the frequency and intensity of floods, droughts, and heatwaves, with Africa expected to be among the global regions hit hardest (Tzachor et al. 2023), affecting ecosystems. As climate impacts continue to negatively affect economies and livelihoods in Africa, there is a need to increase scientific and research capacity and facilities in the continent.

Establishing the African Tree Ring Network (ATRN) working group is, therefore, an opportunity to advance the use of tree rings in the tropics, particularly in Africa in the areas of paleoecology/paleoclimatology reconstructions, ecology, forestry/agroforestry, hydrology, archeology, as a new frontier. In recent years, dendrochronology in Africa has experienced a rapid expansion and is beginning to fill important gaps in an existing chronology network that is dominated almost exclusively by temperate regions (Gebrekirstos et al. 2014, Zuidema et al. 2022).

For instance, based on tree-ring widths in Juniperus procera in Ethiopia, Mokria et al. (2017) reconstructed climate data spanning 350 years. Gebrekirstos et al. (2008) also characterized co-occurring savanna species into opportunist and resilient species based on their response to rainfall variability. A combination of tree ring width and Stable isotopes are also used to reconstruct the Blue Nile water flow (Mokria et al. 2018), and to determine which species is productive and which species is resilient (Gebrekirstos et al. 2009), which species sequesters more carbon (Sanogo et al. 2022) or which species is drought tolerant (Gebrekirstos et al. 2011; Boakye et al. 2016), carbon sequestration of tropical trees (Zuidema et al. 2022). Yet this science is the least developed in the globe.
 
The main scientific objective of this working group is, therefore, to bring together African tree ring scientists and take stock of the development in terms of science, methods, data, and human capacity and facility on the continent.

• We will analyze the challenges and opportunities.
• We will provide improved methods, approaches, and best practices to enable cross-regional data analysis and synthesis to support informed decision-making on pressing environmental questions and climate issues considering its diverse effects on African ecosystems.
• We will organize online meetings and workshops, field training, and citizen science to increase awareness in collaboration with international and regional partners, policy makers, and donors. We will create a link between the tree-ring, modeling, and multi-proxy communities to develop a vibrant network and advance scientific capacity in the continent and beyond. 

References

Gebrekirstos A., Bräuning, A., Sass-klassen, U., Mbow, C., 2014. Opportunities and applications of dendrochronology in Africa. Current Opinion in Environmental Sustainability

Gebrekirstos, A., Mitlöhner, R., Teketay, D., Worbes, M., 2008. Climate growth relationships of the dominant tree species from semi-arid savanna woodland in Ethiopia. Trees.

Gebrekirstos, A., Teketay, D., Fetene, M., Worbes, M., Mitlöhner, R., 2009. Stable carbon isotope ratios in tree rings of co-occurring species from semi-arid tropics in Africa: patterns and climatic signals. Global Planetary Change 66: 253-260.

Mokria, M., Gebrekirstos, A., Abiyu, A., Noordwijk, M., Bräuning, A., 2017. Multi‐century tree‐ring precipitation record reveals increasing frequency of extreme dry events in the upper Blue Nile River catchment. Global Change Biology

Mokria, M., Gebrekirstos, A., Abiyu, A. & Bräuning, A. 2018. Upper Nile River flow reconstructed to A.D. 1784 from tree-rings for a long-term perspective on hydrologic-extremes and effective water resource management. Quat. Sci. Rev. 199, 126–143.

Sanogo K, Gebrekirstos A, Bayala J, van Noordwijk M, 2022. Climate-growth relationships of Daniellia oliveri (Rolfe) Hutch. & Dalziel in the Sudanian zone of Mali, West Africa,
Trees, Forests and People

Tzachor, A. et al. How to reduce Africa’s undue exposure to climate risks. Nature 620, 488–491 (2023).

Zuidema P, et al.  2022 Tropical tree growth driven by dry-season climate variability Nature Geoscience, 15(4), 269-276. https://doi.org/10.1038/s41561-022-00911-8