Abstract
Pollen, geochemical and sedimentological data from Sidi Ali, a montane Moroccan lake, provide a 7000 yr record of changes in climate, catchment vegetation and soil erosion intensity. Diatoms, non-silicious algae, macrophyte fossils and ostracods from the same core record the dynamics of the lake ecosystem. Oxygen isotope and trace-element ratios of benthic ostracods appear to be relatively insensitive to climatic variation in this open lake with low water-residence time, but diatom plankton / periphyton (P/L) ratios show lake-level variations that are probably climate controlled. At least two superimposed processes are recorded, but at different timescales: catchment vegetation and soils show long-term changes due to climate and human impact, whereas P/L ratios suggest century-scale oscillations in lake depth. The timing of changes in algal and macrophyte productivity and carbon cycling within the lake broadly corresponds to changes in terrestrial vegetation, suggesting either that lake nutrient status is linked to catchment vegetation and soils, or that both were influenced by climate. The lack of a sensitive and independent (non-biological) climate proxy makes it more difficult to assess the lake's ecological response to short-term climate variation. Overall, the lake's evolution has been influenced both by catchment-mediated nutrient flux and by changes in water balance, thus having characteristics in common with both temperate and arid zone lakes.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Aaby, B. & B. E. Berglund, 1986. Characterization of peat and lake deposits. In Berglund B.E. (ed.) Handbook of Holocene Palaeoecology and Palaeohydrology. J. Wiley & Sons, London: 231-246.
Anderson, N. J., B. Rippey & A. C. Stevenson, 1993. A comparison of sedimentary and diatom-inferred phosphorus profiles: implications for defining pre-disturbance nutrient condions. Hydrobiologia 253: 357–366.
Barker, P. A., C. N. Roberts, H. F. Lamb, S. van der Kaars & A. Benkaddour, 1994. Holocene lake-level change interpreted from diatom assemblages in lake Sidi Ali, Middle Atlas, Morocco. J. Paleolim 12: 223-234.
Cheddadi, R., H. F. Lamb, J. Guiot & S. van der Kaars, in press. Holocene climatic change in Morocco: A quantitative reconstruction from pollen data. Climate Dynamics
Chivas, A. R., P. De Deckker & J. M. G. Shelley, 1986. Magnesium content of non-marine ostracod shells: A new palaeosalinometer and palaeothermometer. Palaeogeogr. Palaeoclim. Palaeoecol. 54: 43–61.
Dansgaard, W., 1964. Stable isotopes in precipitation. Tellus 16: 436–468.
Dean, W. E. 1974. Determination of carbonate and organic matter in calcareous sediments and sedimentary rocks by loss on ignition: Comparison with other methods. J. Sed. Petrol. 44: 242–248.
Deevey, E. S., 1984. Stress, strain, and stability of lacustrine ecosystems. In Haworth E. & J. W. G. Lund (eds) Lake sediments and environmental history. Leicester University Press, Leicester: 208–209.
El Hamouti, N. 1989: Contribution à la reconstitution de la paléohydrologie et de la paléoclimatologie du Maghreb et du Sahara au Quaternaire supérieur à partir des diatomées. PhD thesis, Université de Paris XI, 280 pp.
Engstrom, D. R & S. R. Nelson, 1991. Paleosalinity from trace elements in fossil ostracodes compared with observational records at Devils Lake, North Dakota, USA. Palaeogeogr. Palaeoclim. Palaeoecol. 83: 295–312.
Faegri, K. & J. Iversen, 1989. Textbook of Pollen Analysis. J. Wiley & Sons, Chichester: 328 pp.
Fritz, S. C., D. R. Engstrom & B. J. Haskell, 1994. 'Little Ice Age' aridity in the North American Great Plains: A high-resolution reconstruction of salinity fluctuations from Devils Lake, North Dakota,USA. The Holocene 4: 69–73.
Grimm, E. C., 1987. CONISS: A FORTRAN 77 program for stratigraphically constrained cluster analysis by the method of incremental sum of squares. Computers and Geosciences 13: 13–35.
Guy-Ohlson, D., 1992. Botryococcus as an aid in the interpretation of palaeoenvironment and depositional processes. Rev. Paleobot. Palynol. 71: 1–15.
Jones, V. J., A. C. Stevenson & R. W. Battarbee, 1989. Acidification of lakes in Galloway, south west Scotland: A diatom and pollen study of the post-glacial history of the Round Loch of Glenhead. J. Ecol. 77: 1–23.
Lamb, H. F. & S. van der Kaars, S. 1995. Vegetational response to Holocene climatic change: Pollen and palaeolimnologic data from the Middle Atlas, Morocco. The Holocene 5: 400–408
Lamb, H. F., U. Eicher & V. R. Switsur, 1989. An 18,000 year record of vegetation, lake-level and climatic change from the Middle Atlas, Morocco. J. Biogeogr. 16: 65–74.
Lamb, H. F., F. Damblon & R. W. Maxted, 1991. Human impact on the vegetation of the Middle Atlas, Morocco, during the last 5000 years. J. Biogeogr. 18: 519–532.
Lamb, H. F., F. Gasse, A. Benkaddour, N. El Hamouti, S. van der Kaars, W. T. Perkins, N. J. Pearce & C. N. Roberts, 1995. Relation between century-scale Holocene arid intervals in tropical and temperate zones. Nature 373: 134–137
Nielsen, H. & I. Sørensen, 1992. Taxonomy and stratigraphy of late-glacial Pediastrum taxa from Lysmosen, Denmark-a preliminary study. Rev. Paleobot. Palynol. 74: 55–75.
Oldfield, F., 1977. Lakes and their drainage basins as units of sediment-based ecological study. Progress in Physical Geography 1: 460–504.
Pienitz R. & Smol, J. P. (1993) Diatom assemblages and their relationship to environmental variables in lakes from the boreal forest-tundra ecotone near Yellowknife, Northwest Territories, Canada. Hydrobiologia 269: 391–404.
Reille, M., 1976. Analyse pollinique de sédiments postglaciaires dans le Moyen Atlas et le Haut Atlas marocains: Premiers résultats. Ecologia Mediterranea 2: 153–170.
Rozanski, K., L. Araguás-Araguás & R. Gonfiantini, 1993. Isotopic patterns in modern global precipitation. In Swart P. K., K. C. Lohmann, J. A. McKenzie, & S. Savin (eds.) Climate Change in Continental Isotopic Records. Am. Geophys. Union. Geophys. Monogr. 78: 1–36.
Siegenthaler, U. & H. Oeschger, 1980. Correlation of 18O in precipitation with temperature and altitude. Nature 285: 314–317.
Stuiver, M. 1970. O and C isotope ratios of fresh-water carbonates as climatic indicators. J. Geophys. Res. 75: 5247–5257.
Stuiver, M. & P. J. Reimer, 1993. Extended 14C data base and revised CALIB 3.0 14C age calibration program. Radiocarbon 35: 215–230.
Till, C. & J. Guiot, 1990. Reconstruction of precipitation in Morocco since 1000 AD based on Cedrus atlantica tree-ring widths. Quat. Res. 33: 337–351.
Tyson, R. V., 1995. Sedimentary Organic Matter-Organic Facies and Palynofacies. Chapman & Hall, London: 615 pp.
Xia, J., E. Ito & D. R. Engstrom, 1997a. Geochemistry of ostracod calcite: Part 1. An experimental determination of oxygen isotope fractionation. Geoch. Cosmoch. Acta. 61: 377–382.
Xia, J., D. R. Engstrom & E. Ito, 1997b. Geochemistry of ostracod calcite: Part 2. The effects of water chemistry and seasonal temperature variation on Candona rawsoni. Geoch. Cosmoch. Acta. 61: 383–391.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lamb, H., Roberts, N., Leng, M. et al. Lake evolution in a semi-arid montane environment: response to catchment change and hydroclimatic variation. Journal of Paleolimnology 21, 325–343 (1999). https://doi.org/10.1023/A:1008099602205
Issue Date:
DOI: https://doi.org/10.1023/A:1008099602205