Abstract
Prolific growth of Typha australis in the lower part of the Senegal River and the Lac de Guiers resulted from changed ecological conditions following the construction of two high dams in the Senegal River. Fluctuation of the water level has decreased markedly and the water has changed from brackish to fresh as the inflow of salt water from the ocean is prevented. The efficiency of a hydraulic weed cutting boat (model Conver 480 H) has been tested in various plots in the Lac de Guiers. This lake, connected with the Senegal River, is economically very important as it is the city of Dakar's major drinking water supply and also provides irrigation water for vast agricultural areas. Cutting, performed at 20 cm and 50 cm below the water surface, was very effective in removing Typha stands. However, due to the excessively thick stems of the Typha plants, cutting took much more time compared to similar operations in Europe. It was estimated that approximately 35 h were required to clear one ha of dense Typhastands. Directly after cutting re-growth was observed during a relatively brief period (approximately three months), however, subsequently all newly formed growth tips in the plots had suddenly disappeared. It was concluded that this sudden collapse was linked to a destruction of the root zone due to anoxic conditions. Eventual re-growth was relatively slow as after one year the plots were still largely free from Typha plants. Efficiency of mowing was not related significantly to depth of cutting.
Similar content being viewed by others
References
Armstrong, W., 1978. Root aeration in wetland conditions. In Hook, D. D. & R. M. M. Crawford (eds), Plant Life in Aerobic Environments. Ann Arbor Science publishers, Ann Arbor: 269–297.
Cogels, F. X., A. Thiam & J. Y. Gac, 1993. Premier effets des barrages du fleuve Sénégal sur le lac de Guiers. Rev. Hydrobiol. trop. 26: 105–117.
Husák, J., 1978. Control of reed and reed mace stands by cutting. In Dykyjova, D. & J. Kvet (eds), Pond Littoral Ecosystems: Ecological Studies 28. Springer Verlag, Berlin: 404–408.
John, D. M., 1986. The inland waters of tropical West Africa. An introduction and botanical review. Arch. Hydrobiol. Beih. 23: 104–219.
Sale, P. J. M. & R. G. Wetzel, 1983. Growth and metabolism of Typha species in relation to cutting treatments. Aquat. Bot. 15: 335–348.
Sharma, K. P. & S. P. S. Kushwaha, 1990. Effect of cutting of aboveground organs of Typha angustata Bory & Chaub on its growth and total chlorophyll content. Aquat. Bot. 36: 293–296.
Singh, S. P., S. S. Pahuja & M. K. Moolani, 1976. Cultural control of Typha angustata at different stages of growth. In Varshney, C. K. & J. Rzóska (eds), Aquatic Weeds in S.E. Asia. Proceedings of a Regional Seminar on Noxious Aquatic Vegetation. New Delhi. Dr W. Junk Publishers, The Hague: 245–247.
Thiam, A., R. Ndiaye & M. Ouattara, 1993. Macrophytes aquatiques et zooplancton du lac de Guiers. Institut des Sciences de l'Environnement (ISE). Projet 2: ISE/FUL, Report: 55 pp.
Wade, M., 1990. Physical control of aquatic weeds. In Pieterse, A. H. & K. J. Murphy (eds), Aquatic Weeds. Oxford University Press, Oxford: 93–135.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hellsten, S., Dieme, C., Mbengue, M. et al. Typha control efficiency of a weed-cutting boat in the Lac de Guiers in Senegal: a preliminary study on mowing speed and re-growth capacity . Hydrobiologia 415, 249–255 (1999). https://doi.org/10.1023/A:1003877201612
Issue Date:
DOI: https://doi.org/10.1023/A:1003877201612