Murray-Hudson, M.; Mmopelwa, G.(Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)
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Abstract:
Most work globally on Phragmites spp. has been done in temperate northern hemisphere localities, where winter low temperatures and short day lengths cause a seasonal decrease in growth. In this study, we report above-ground stem length-mass relationships, stem densities and daily growth rates in 3 Phragmites australis reedbeds in the flood-pulsed, subtropical Okavango Delta, with the aim of assessing the economic value of this plant, which is widely used throughout north-western Botswana for cladding house walls and fencing yards. Stem density averaged 77m¯² in 32 plots. Length-mass relationships were best represented by a power function y = 8.05x¹•⁸⁵, where y is the dry mass in grams and x is the length in meters (r²=0.895). The mean daily growth rate was 0.015 m and did not appear to vary systematically with season. The maximum standing crop calculated from stem length was 2.89 kg m¯², and occurred in May 2005. Annual above-ground production was conservatively estimated at 20-30 t ha¯¹. Assuming that harvesting takes place not more than once annually, reed beds in the Okavango Delta are worth ~US$ 45,000 ha¯¹ at market. This land use value is over 90 times that of flood recession agriculture in the same area.