摘要
African wetlands include dambos or headwater valley grasslands in the upper regions of catchments, circular pan grasslands in drainage sumps, linear riverine grasslands in the mid regions of catchments and broad floodplains, swamps and deltas in the lower regions of catchments. Plant zonation on flood frequency and duration gradients occurs in predictable sequences across Africa and this variation combined with increasing retention of soil moisture for plant growth over the dry season with increasing flooding provides critical resource heterogeneity for herbivores. Consequently, wetlands are essential dry-season habitats for wild and domestic herbivore populations across Africa, often providing key resources that buffer herbivore population numbers in the face of severe dry seasons and droughts. Floodplain peripheries and shallow to intermediate-depth floodplains are generally preferred over the early dry season, with deep floodplains and swamps being used by the late dry season and during droughts. Wetland grasslands are generally able to withstand extremely heavy grazing over the dry season without becoming degraded because they are inaccessible to grazers during the period of flooding over the wet season, giving plants a full growing season’s recovery period, as well as by wetland grasses storing a large proportion of their biomass in deep root systems and rhizomes. African wetlands are under siege by upstream damming and by agricultural projects and further/reinforced conservation measures are needed to protect them, such as ecologically designed water releases from dams to maintain flooding regimes and prevention of agriculture on key floodplains for grazers. Keywords Dambos Floodplains Swamps Dry season range Key resource Flood inundation frequency