WETLANDS SUCH AS THE OKAVANGO
Delta, located in semi-arid regions, are
of great ecological, environmental and
socio-economic importance. In most cases,
however, few data exist on nutrient cycling in
these areas. This paper presents preliminary
results of an ongoing study, which investigates
the influence of seasonal flooding on
soil nutrient status in the different vegetation
communities of the delta. Soil K, Na, and pH
significantly increased with a decrease in soil
moisture, with the values increasing from the
primary floodplains to the islands communities.
Available P, Ca and Mg decreased as the
elevation gradient increased from the
riverbed. Although nutrient status generally
was highest in the floodplain vegetation areas
adjacent to the riverbed, there was no significant
difference in available P, Ca and Mg
within the vegetation communities. Calcium
levels in the different vegetation zones were
more influenced by rainfall than floodplain
vegetation community. Higher soil Ca was
observed in the rainy season, while elevated
Mg was recorded after the rains. Overall,
these results indicate that flooding is an
essential aspect of the Okavango Delta as it
may be a primary source of some of the soil
nutrients that support the high diversity of
plants sustaining the delta’s ecosystem.