ORIGINAL PAPER Primary production in papyrus (Cyperus papyrus L.) of Rubondo Island, Lake Victoria, Tanzania Bakari Mnaya Æ Takashi Asaeda Æ Yustina Kiwango Æ Elisamehe Ayubu Received: 27 November 2006 / Accepted: 27 November 2006 / Published online: 13 January 2007 Ó Springer Science+Business Media B.V. 2007 Abstract Above- and below-ground production and morphological characteristics of papyrus wetlands were measured at monthly intervals from July 2005 to June 2006 at Rubondo Island, Lake Victoria, Tanzania. The average value of live culm biomass (5,789 ± 435 g DW m –2 ) was higher than that of umbel biomass (2,902 ± 327 g DW m –2 ) by 50%. Root to rhi- zome means biomass value ratio was 1:1.8, rhizome biomass (4,144 ± 452 g DW m –2 ) being higher than roots biomass (2,254 ± 314 g DW m –2 ) by 45%. Direct proportion was observed between shoot density and culm–unit (culms and umbels) biomass. The average value of detritus/litter biomass (1,306 ± 315 g DW m –2 ) was less than total aerial biomass by 86%.The values of bio- mass are average of 12 sampling months from July 2005 to June 2006. Keywords Rubondo Island Á Lake Victoria Á Papyrus Á Primary production Introduction One of the most impressive features of the tropical wetland ecosystems is their high biomass production and productivity rates of the vegeta- tions, especially papyrus that has a productivity ranging between 48 and 143 t ha –1 year –1 (Thompson et al. 1979). Various studies of papyrus primary production has been carried out in different papyrus wetlands of lake Victoria but none has been carried out in Tanzanian side of the lake and particularly in the protected area like Rubondo Island. Aerial bio- mass in those studies varied considerably from site to site (Thompson et al. 1979; Muthuri et al. 1989). The natural distribution of papyrus is esti- mated to be confined to a belt across equatorial central Africa within 17° N and 29° S latitudes, and its altitudinal distribution is from sea level to 2000 m (Jones and Muthuri 1985). Lake Victoria is within this belt and is one of the areas in which most extensive papyrus wetlands and swamps are found. Papyrus (Cyperus papyrus L.) is one of the largest herbaceous species with its culm growing up to a height of 5 m above the ground (Jones and Muthuri 1985). The culm is topped by characteristically large, spherically shaped, repro- ductive umbels that serve also as main photosyn- thetic surface (Jones and Humphries 2002). Papyrus is a rhizomatous, perennial plant which B. Mnaya (&) Á T. Asaeda Department of Environmental Science and Human Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8770, Japan e-mail: jmnaya@yahoo.com Y. Kiwango Á E. Ayubu Rubondo Island National Park, P. O. Box 111, Geita, Mwanza, Tanzania 123 Wetlands Ecol Manage (2007) 15:269–275 DOI 10.1007/s11273-006-9027-1