Journal of Paleolimnology

, Volume 40, Issue 2, pp 583–601 | Cite as

A record of vegetation dynamics and lake level changes from Lake Emakat, northern Tanzania, during the last c. 1200 years

  • Maria RynerEmail author
  • Karin Holmgren
  • David Taylor
Original Paper


Analyses of down-core variations in pollen and charcoal in two short cores of lake sediment and wood samples taken from the in situ remains of Nuxia congesta from Lake Emakat, a hydrologically-closed volcanic crater lake occupying the Empakaai Crater in northern Tanzania, have generated evidence of past vegetation change and lake level fluctuations. Eight AMS radiocarbon (14C) dates on bulk samples of lake sediment provide a chronological framework for the two cores and indicate that the sediment record analysed incorporates the last c. 1200 years. The in situ remains of a Nuxia congesta tree, now standing in deep water, were dated with three additional AMS 14C dates, suggesting tree growth within the interval ∼1500–1670 AD. Down-core variations in pollen from terrestrial taxa, particularly the montane forest trees Hagenia abyssinica and Nuxia congesta, indicate a broad period of generally more arid conditions in the catchment to c. 1200 AD and at a prolonged period between c. 1420 and 1680 AD. Variations in pollen from plants in lake margin vegetation indicate low lake levels, presumably as a result of reduced effective precipitation, contemporary with indications of relatively dry conditions mentioned above, but also during the late 18th and the late 19th centuries. The presence of charcoal throughout both cores indicates the frequent occurrence of vegetation fires. An increase in burning, evident in the charcoal data and dated to the early to mid second millennium AD, could relate to an expansion of human population levels and agricultural activity in the region.


Africa Climate change Palaeoecology Lake level change Tanzania 



The authors are grateful for the financial support for this research provided by the Swedish Research Council (VR), the Granholm Foundation, the Swedish Society for Anthropology and Geography (SSAG), Lillemor and Hans W:son Ahlmann, Axel Lagrelius, Carl Mannerfelt and Margit Ahltins foundations, and the Swedish Foundation for International Cooperation in Research and Higher Education (STINT). The radiocarbon dates were provided by Ångström Laboratory, Div. of Ion Physics, 14C-lab, UPPSALA, Sweden and Poznań Radiocarbon Laboratory, ul. Rubież 46, 61–612 Poznań, Poland. Helena Öberg kindly provided us with a sediment date. We thank our collaborator in Tanzania, Alfred Muzuka, Institute of Marine Science, University of Dar es Salaam. We would also like to thank Guillaume Buchet for his assistance at the palynological laboratory at CEREGE. The Tanzania Commission for Science and Technology (COSTECH) and Tanzania Wildlife Research Institute (TAWIRI) kindly authorised research permission and fieldwork. Particular thanks for assistance while in the field are due to Victor Runyoro, a conservation authority officer at Ngorongoro. Finally, we are grateful to two anonymous referees of an earlier version of this paper for their highly constructive comments.


  1. Alin SR, Cohen AS (2003) Lake-level history of Lake Tanganyika, East Africa, for the past 2500 years based on ostracode-inferred water-depth reconstruction. Palaeogeogr Palaeoclimatol Palaeoecol 199:31–49CrossRefGoogle Scholar
  2. Barker P, Telford R, Merdaci O, Williamson D, Taieb M, Vincens A, Gibert E (2000) The sensitivity of a Tanzanian crater lake to catastrophic tephra input and four millennia of climate change. The Holocene 10:303–310CrossRefGoogle Scholar
  3. Barns TA (1923) Across the Great Craterland to the Congo: a sequel to “the wonderland of the eastern Congo”. Ernest Benn, LondonGoogle Scholar
  4. Bonnefille R (1971) Atlas des pollens d’Ethiopie Principales espèces des forêt de montagne. Pollen et Spores 13:1–27Google Scholar
  5. Bonnefille R, Riollet G (1980) Pollen des savanes d’ Afrique Orientale. CNRS, ParisGoogle Scholar
  6. Bonnefille R, Mohammed U (1994) Pollen-inferred climatic fluctuations in Ethiopia during the last 3000 years. Palaeogeogr Palaeoclimatol Palaeoecol 109:331–343CrossRefGoogle Scholar
  7. Clark JS (1988) Particle motion and the theory of charcoal analysis—source area, transport, deposition, and sampling. Quaternary Res 30:67–80CrossRefGoogle Scholar
  8. Darbyshire I, Lamb H, Umer M (2003) Forest clearance and regrowth in northern Ethiopia during the last 3000 years. The Holocene 13:537–546CrossRefGoogle Scholar
  9. Ehret C (1974) Cushites and the highland and plains nilotes to AD 1800. In: Ogot BA (ed) Zamani: a survey of East African history. East African Publishing House, Nairobi, pp 150–169Google Scholar
  10. Eriksson MG, Bonnefille R, Lafon S (1999) Recent lake level variations in Lake Haubi, central Tanzania, interpreted from pollen and sediment studies. J Paleolimnol 22:457–473CrossRefGoogle Scholar
  11. Faegri K, Iversen J (1989) Textbook of pollen analysis. Blackwell, OxfordGoogle Scholar
  12. Fetene M, Feleke Y (2001) Growth and photosynthesis of seedlings of four tree species from a dry tropical afromontane forest. J Tropical Ecol 17:269–283CrossRefGoogle Scholar
  13. Fosbrooke H (1972) Ngorongoro: the eight wonder. Andre Deutsch Ltd., LondonGoogle Scholar
  14. Frame G, Frame LH, Spillett JJ (1975) An ecological survey and development plan for the Empakaai Crater ecosystem (Ngorongoro Conservation Area). Serengeti Research Contribution 212Google Scholar
  15. Garcin Y, Williamson D, Bergonzini L, Radakovitch O, Vincens A, Buchet G, Guiot J, Brewer S, Mathé PE, Majule A (2007) Solar and anthropogenic imprints on Lake Masoko (southern Tanzania) during the last 500 years. J Paleolimnol 37:475–490CrossRefGoogle Scholar
  16. Gillson L (2006) Large infrequent disturbance in an East African savanna. Afr J Ecol 44:458–467CrossRefGoogle Scholar
  17. Grimm EC (1987) CONISS: a FORTRAN 77 program for stratigraphically constrained cluster analysis by the method of incremental sum of squares. Comput Geosci 13:13–35CrossRefGoogle Scholar
  18. Grimm EC (1991–1993) Tilia 2.04 and Tilia graph. Illinois State University, IllinoisGoogle Scholar
  19. Hamilton AC (1972) The interpretation of pollen diagrams from highland Uganda. Palaeoecol Afr 7:45–149Google Scholar
  20. Hamilton AC (1982) Environmental history of East Africa—a study of the Quaternary. Academic Press Ltd., LondonGoogle Scholar
  21. Hamilton AC (1987) Vegetation and climate of Mt Elgon during the late Pleistocene and Holocene. Palaeoecol Afr Surround Islands 18:283–304Google Scholar
  22. Hay LR (1976) Geology of the Olduvai Gorge—a study of sedimentation in a semiarid basin. University of California Press, BerkelyGoogle Scholar
  23. Herlocker DJ, Dirschl HJ (1972) Vegetation of the Ngorongoro conservation area, Tanzania. Canadian Wildlife Service Report Series 19Google Scholar
  24. Homewood KM, Rodgers WA (1991) Masaailand ecology—pastoralist development and wildlife in Ngorongoro, Tanzania. Cambridge University Press, CambridgeGoogle Scholar
  25. Johnson TC, Barry SL, Chan Y, Wilkinson P (2001) Decadal record of climate variability spanning the past 700 yr in the Southern Tropics of East Africa. Geology 29:83–86CrossRefGoogle Scholar
  26. Lamb H, Darbyshire L, Verschuren D (2003) Vegetation response to rainfall variation and human impact in central Kenya during the past 1100 years. The Holocene 13:285–292CrossRefGoogle Scholar
  27. Lejju BJ, Taylor D, Robertshaw P (2005) Late-Holocene environmental variability at Munsa archaeological site, Uganda: a multicore, multiproxy approach. The Holocene 15:1044–1061CrossRefGoogle Scholar
  28. Legesse D, Gasse F, Radakovitch O, Vallet-Coulomb C, Bonnefille R, Verschuren D, Gibert E, Barker P (2002) Environmental changes in a tropical lake (Lake Abiyata, Ethiopia) during recent centuries. Palaeogeogr Palaeoclimatol Palaeoecol 187:233–258CrossRefGoogle Scholar
  29. Lind EM, Morrison MES (1974) East African vegetation. Longman, LondonGoogle Scholar
  30. Lyaruu HV, Eliapenda S, Backeus I (2000) Floristic, structural and seed bank diversity of a dry Afromontane forest at Mafai, central Tanzania. Biodivers Conserv 9:241–263CrossRefGoogle Scholar
  31. Maley J, Brenac P (1998) Vegetation dynamics, palaeoenvironments and climatic changes in the forests of western Cameroon during the last 28,000 years BP. Rev Palaeobot Palynol 99:157–187CrossRefGoogle Scholar
  32. Marchant R, Taylor D (1998) Dynamics of montane forest in central Africa during the late Holocene: a pollen-based record from western Uganda. The Holocene 8:375–381CrossRefGoogle Scholar
  33. Marchant R, Taylor D (2000) Pollen representivity of montane forest taxa in south-west Uganda. New Phytol 146:515–525CrossRefGoogle Scholar
  34. Marchant R, Mumbi C, Behera S, Yamagata T (2006) The Indian Ocean dipole—the unsung driver of climatic variability in East Africa. Afr J Ecol 45:4–16CrossRefGoogle Scholar
  35. Mksay ES, Livingstone D, Davis OK (2005) Paleolimnological investigations of anthropogenic environmental change in Lake Tanganyika: V. Palynological evidence for deforestation and increased erosion. J Paleolimnol 34:73–83CrossRefGoogle Scholar
  36. Muzuka ANN, Ryner M, Holmgren K (2004) 12,000-Year, preliminary results of the stable nitrogen and carbon isotope record from the Empakai Crater lake sediments, northern Tanzania. J Afr Earth Sci 40:293–303CrossRefGoogle Scholar
  37. Nicholson SE (1998) Historical fluctuations of Lake Victoria and other lakes in the northern Rift valley of East Africa. In: Lehman JT (ed) Environmental change and response in East African Lakes. Kluwer, Dordrecht, pp 7–29Google Scholar
  38. Noad TC, Birnie A (1989) Trees of Kenya. Nairobi, KenyaGoogle Scholar
  39. Patterson WA, Edwards KJ, Maguire DJ (1987) Microscopic charcoal as a fossil indicator of fire. Quaternary Sci Rev 6:3–23CrossRefGoogle Scholar
  40. Reimer PJ, Baillie MGL, Bard E, Bayliss A, Beck JW, Bertrand CJH, Blackwell PG, Buck CE, Burr GS, Cutler KB, Damon PE, Edwards RL, Fairbanks RG, Friedrich M, Guilderson TP, Hogg AG, Hughen KA, Kromer B, McCormac G, Manning S, Ramsey CB, Reimer RW, Remmele S, Southon JR, Stuiver M, Talamo S, Taylor FW, van der Plicht J, Weyhenmeyer CE (2004) IntCal04 terrestrial radiocarbon age calibration, 0–26 cal kyr BP. Radiocarbon 46:1029–1058Google Scholar
  41. Robertshaw P, Taylor D, Doyle S, Marchant R (2004) Famine, Climate and Crises in western Uganda. In: Battarbee R, Gasse F, Stickely C (eds) Past climate variability through Europe and Africa, Kluwer, Amsterdam, pp 535–549CrossRefGoogle Scholar
  42. Russell JM, Johnson TC (2007) Little Ice Age drought in equatorial Africa: intertropical convergence zone migrations and El Nino-southern oscillation variability. Geology 35:21–24CrossRefGoogle Scholar
  43. Russell JM, Verschuren D, Eggermont H (2007) Spatial complexity of “Little Ice Age” climate in East Africa: sedimentary records from two crater lake basins in western Uganda. The Holocene 17:183–193CrossRefGoogle Scholar
  44. Ryner MA, Bonnefille R, Holmgren K, Muzuka A (2006) Vegetation changes in Empakaai Crater, northern Tanzania, at 14,800–9300 cal yr BP. Rev Palaeobot Palynol 140:163–174CrossRefGoogle Scholar
  45. Ryner M, Gasse F, Rumes B, Verschuren D (2007) Climatic and hydrological instability in semi-arid equatorial East Africa during the late Glacial to Holocene transition: a multi-proxy reconstruction of aquatic ecosystem response in northern Tanzania. Palaeogeogr Palaeoclimatol Palaeoecol 248:440–458CrossRefGoogle Scholar
  46. Rånge K (2001 The Empakaai Crater—sammanställning övervegetationsförhållandena I Empakaaikratern, norra Tanzania, under augusti 2000. MSc student report, Dept Phys Geogr Quat Geol, Stockholm UniversityGoogle Scholar
  47. Ssemmanda I, Ryves DB, Bennike O, Appleby PG (2005) Vegetation history in western Uganda during the last 1200 years: a sediment-based reconstruction from two crater lakes. The Holocene 15:119–132CrossRefGoogle Scholar
  48. Stager JC, Ryves D, Cumming BF, Meeker LD, Beer J (2005) Solar variability and the levels of Lake Victoria, East Africa, during the last millenium. J Paleolimnol 33:243–251CrossRefGoogle Scholar
  49. Struhsaker T, Odegaard A, Ruffo C, Steele R (1989) Forest conservation and management. Technical Report no 5. Ngorongoro Conservation and Development Project. IUCN Regional Office, NairobiGoogle Scholar
  50. Sutton J (1993) Becoming Masaai. In: Spear T, Waller C (eds) Being Masaai. Ethnicity and identity in East Africa. Eastern African Studies. Ohio University Press, Athens, pp 38–60Google Scholar
  51. Talbot MR, Livingstone DA (1989) Hydrogen index and carbon isotopes of lacustrine organic-matter as lake level indicators. Palaeogeogr Palaeoclimatol Palaeoecol 70:121–137CrossRefGoogle Scholar
  52. Taylor D, Robertshaw P, Marchant RA (2000) Environmental change and political-economic upheaval in precolonial western Uganda. The Holocene 10:527–536CrossRefGoogle Scholar
  53. Taylor D, Lane PJ, Muiruri V, Ruttledge A, McKeever RG, Nolan T, Kenny P, Goodhue R (2005) Mid- to late-holocene vegetation dynamics on the Laikipia Plateau, Kenya. The Holocene 15:837–846CrossRefGoogle Scholar
  54. Turner R, Kelly A, Roberts N (in press) A critical assessment and experimental comparison of microscopic charcoal extraction method In: Fiorentino G, Magri D (eds) Charcoal from the past: cultural and palaeoenvironmental implications. Proceedings of the Third International Meeting of Anthracology, Cavallino (Lecce), June 2004. BAR International Series, Archaeopress, OxfordGoogle Scholar
  55. Verschuren D, Laird KR, Cumming BF (2000) Rainfall and drought in equatorial east Africa during the past 1,100 years. Nature 403:410–414CrossRefGoogle Scholar
  56. Verschuren D (2004) The last 2000 years in tropical Africa. In: Battarbee R, Gasse F, Stickely C (eds) Past climate variability through Europe and Africa. Kluwer, Amsterdam, pp 139–158CrossRefGoogle Scholar
  57. Vestrin M (2006) Topography and land cover in the Crater Highlands and Engaruka Basin, northern Tanzania. Student project, Dept Phys Geogr Quat Geol, Stockholm UniversityGoogle Scholar
  58. Vincens A, Williamson D, Thevenon F, Taieb M, Buchet G, Decobert M, Thouveny N (2003) Pollen-based vegetation changes in southern Tanzania during the last 4200 years: climate change and/or human impact. Palaeogeogr Palaeoclimatol Palaeoecol 198:321–334CrossRefGoogle Scholar
  59. Vincens A, Buchet G, Williamson D, Taieb M (2005) A 23,000 yr pollen record from Lake Rukwa (8°S, SW Tanzania): new data on vegetation dynamics and climate in Central Eastern Africa. Rev Palaeobot Palynol 137:147–162CrossRefGoogle Scholar
  60. White F (1983) The vegetation of Africa. UNESCO, ParisGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  1. 1.Department of Physical Geography and Quaternary GeologyStockholm UniversityStockholmSweden
  2. 2.Department of Geography, Trinity CollegeUniversity of DublinDublin 2Ireland

Personalised recommendations