Plant Biomass Density as an Indicator of Food Supply for Elephants (Loxodonta Africana) in Waza National Park, Cameroon

Abstract

We studied the aboveground biomass density of plants, potentially available as a food supply for elephants, Loxodonta africana, in the Waza National Park, Cameroon during the dry season, from November 2009 through March 2010. The aboveground biomass of trees in the Woodland and Acacia seyal shrubland zones, were 16.87 tonsDM/ha and 10.99 tonsDM/ha respectively (mean 13.93 ± 4.16 tonsDM/ha). Aboveground biomass density in the herbaceous layer was 2.62, 4.21 and 6.9 tonsDM/ha, in the Woodland, Acacia seyal shrubland and Floodplain zones, respectively (mean 4.58 ± 2.16 tonsDM/ha), the difference between the vegetation zones being significant. The overall aboveground plant biomass density of the park averaged 13.86 ± 6.4 tonsDM/ha, however the harvestable food supply for elephants was a small portion of that estimate. The estimated plant biomass represented an average for the dry season, which is more useful for long-term planning purposes than for annual predictions of the level of forage production in the dry season. To minimize elephant encroachment into cultivated fields, it is necessary to estimate the park's carrying capacity and regulate the population size if necessary. This however will rely on the long-term prediction of forage production in the Waza National Park through continuous measurements of plant biomass density during the dry season.