Species diversity of the Okavango Delta, Botswana

Abstract

In the Okavango Delta (about 28,000 km 2 ) the number of identifi ed species is 1,300 for plants, 71 for fi sh, 33 for amphibians, 64 for reptiles, 444 for birds, and 122 for mammals. The local occurrence of different species of these taxonomic groups in the Okavango Delta is mainly due to a hydrological gradient from permanent streams and swamps to seasonal fl oodplains, riparian woodlands, and dry woodlands. This level of species diversity is normal for the southern African region, and all analyzed aquatic groups are composed of ubiquitous species with an additional signifi cant proportion of species originating from northern, more tropical systems. Cyclical variations in climate over thousands of years have created a huge wetland complex in the upper Zambezi and Okavango Rivers during wet phases. This wetland complex has fragmented into the Okavango Delta and other large wetlands in Zambia during dry phases. There are no endemic species in the Okavango Delta while the Southcentral African wetland complex is a centre of endemism. Species diversity of the Okavango Delta is a consequence of this unique environment, with dynamic shifts in fl ooding patterns that in turn force constant changes in patterns of plant succession and dependent animals. Temporal variations in fl ooding also cause accumulation and sudden mobilization of nutrients which are readily used by well adapted plant species. As a consequence, locally high biological productivity occurs, which in turn results in high numbers of grazing mammals.

Biogeochemical processes along a nutrient gradient in a tropical ombrotrophic peatland

“…Low diversity tree communities are typical of Central American wetlands (Keogh et al 1999;Ellison 2004;Ramberg et al 2006;Lopez and Kursar 2007). For example, the low diversity in San San Pond Sak is similar to that in forested wetlands in Mexico (Shannon index 1.95; Moreno-Casasola et al 2009) and lowland forest swamp in Costa Rica (Shannon index 1.99-2.56; Webb and Peralta 1998).…”

Gillnet selectivity for the north African catfish, Clarias gariepinus (Actinopterygii: Siluriformes: Clariidae), from the Upper Okavango Delta, Botswana

“…The Delta is an alluvial fan covering almost 40 000 km 2 with a mean surface gradient of approximately 1 : 3700 in which the infl ow of water and sediment from the Okavango River are spread across a meandering convoluted surface through a complex system of channels and fl oodplains (McCarthy et al 1998). The Okavango Delta is one of Africa's most pristine Delta areas and it is rich in biodiversity with a large variety of habitats (Ramberg et al 2006). Data collection.…”

Seasonal changes of biodiversity patterns and habitat conditions in a flooded savanna - The Cameia National Park Biodiversity Observatory in the Upper Zambezi catchment, Angola

“…Though the recorded number of 209 species for Cameia National Park is much lower (Okavango Delta: 444 species; Liuwa Plain National Park: 349 species), nevertheless Accipitridae, Sylviidae, Ploceidae, and Ardeidae are particularly prevalent (African Parks, 2017;Leonard, 2010;Ramberg et al, 2006). This leads to the conclusion that either the Cameia National Park is severely impoverished with regard to bird species or, more likely, that data defi ciency is great and more investigation is needed (see below).…”