East African halophytics

The Etosha Pan halophytics ecoregion lies entirely within Etosha National Park in northern Namibia, encompassing a vast saline depression of roughly 4,850 square kilometers that forms part of the Cuvelai-Etosha Basin and is the remnant of a large inland Pliocene lake. This is the largest pan system in Namibia, mostly dry cracked clay that floods with a thin, heavily salted sheet of water after good rains. Vegetation is sparse and salt-tolerant: the pan surface is colonized by grasses such as Sporobolus spicatus that flush quickly after rain, while dense mopane woodland frames the surrounding margins. The climate is harsh and strongly seasonal, with a mean annual rainfall near 430 millimeters falling mostly in late summer, three distinct seasons (hot and wet, cool and dry, hot and dry), and temperatures swinging from below freezing in winter to over 45 degrees Celsius in summer. The pan is a Ramsar wetland of international importance and a crucial breeding ground, drawing up to 1.1 million flamingos in flood years alongside its flagship great white pelican, and the park supports one of the largest black rhino populations in the world.

The Inner Niger Delta flooded savanna occupies the vast inland delta of the Niger River in central Mali, a green oasis set within the semi-arid Sahel just south of the Sahara between the towns of Djenné and Tombouctou. It is the largest inland wetland in West Africa and the second largest on the continent after Botswana's Okavango Delta. Its defining rhythm is seasonal flooding: rains falling on Guinea's Fouta Djalon highlands from roughly May to September send a flood surge that reaches the delta around October, expanding the wetland dramatically before it contracts in the hot dry months. Characteristic plants include bourgou (Echinochloa stagnina) and beardgrass (Andropogon gayanus) on the floodplains, flooded forests of Acacia kirkii with some Ziziphus mauritiana, and stands of doum palm (Hyphaene thebaica) and African fan palm (Borassus aethiopum). The delta is a globally important bird wintering ground, drawing over a million waterbirds in wet years including hundreds of thousands of garganey and northern pintail, with the Nile monitor as its flagship species and several Ramsar sites recognizing its value. Gardeners in hot, strongly seasonal climates may know the heat- and flood-tolerant doum and Borassus fan palms as striking architectural ornamentals native to this region.

The Lake Chad flooded savanna is an Afrotropic flooded-grassland ecoregion centered on the basin of Lake Chad, straddling the borders of Cameroon, Chad, Niger, and Nigeria. It is a mosaic of open water, papyrus and reed beds, seasonally flooded grasslands, and Acacia woodland: the southern lake supports Cyperus papyrus, Phragmites mauritianus, and Vossia cuspidata, the saltier north favors Phragmites australis and Typha, and Acacia seyal is the predominant tree of the drier margins. The climate is tropical and dry, with around 320 mm of rainfall a year concentrated in a June-to-October wet season, so the lake depends heavily on the Chari and Logone Rivers rather than on local rain. It is a critical refuge for waterbirds, hosting many wetland species and large numbers of Palearctic migrants such as ruff, with the secretary bird serving as its flagship species, though the lake has shrunk dramatically in recent decades under pressure from drought, water diversion, and agriculture. For gardeners, the region's native flora includes ornamental wetland and dryland genera grown elsewhere, notably papyrus (Cyperus) and Acacia.

The Makgadikgadi Halophytics ecoregion occupies the vast Makgadikgadi Pan complex of northeastern Botswana, a salt-encrusted basin southeast of the Okavango Delta and ringed by the Kalahari that holds two major pans, Ntwetwe and Sua, along with many smaller ones. It is the remnant of an enormous ancient lake that dried up tens of thousands of years ago, leaving a flat expanse of soda-saturated clay fed seasonally by the Boteti and Nata rivers. The pan floors are almost devoid of higher plants apart from a thin film of blue-green algae, while their wetter fringes grade into salt marshes and grasslands where salt-tolerant grasses take hold, and the surrounding savanna carries scattered baobabs. The climate is semi-arid, with rain falling mainly as summer thunderstorms and droughts recurring in roughly seven-year cycles. Sua Pan is the most important breeding site in Africa for the greater flamingo, the ecoregion's flagship species, and supports southern Africa's largest breeding population of lesser flamingo, with much of the region protected within Makgadikgadi and Nxai Pan National Park.

The Sudd flooded grasslands form one of Africa's largest wetlands, spreading across the White Nile floodplain in South Sudan with a marginal reach into Ethiopia. Vegetation is arranged in zones tied to flood depth: dense stands of papyrus (Cyperus papyrus), reeds such as Phragmites, and cattail (Typha) dominate the permanently wet channels, while floating-rooted hippo grass (Vossia cuspidata) and seasonally flooded swards of wild rice and Echinochloa grasses occupy the shallower margins. The climate is hot and strongly seasonal, with rains falling roughly April to September under the migrating Intertropical Convergence Zone and the wetter south receiving more than the drier north. The Sudd is a biodiversity stronghold, supporting over 400 bird species and the world's largest population of the shoebill, and serving as the stage for one of Earth's greatest mammal migrations as white-eared kob, tiang, and Mongalla gazelle move across the plains. Gardeners may recognize papyrus, native here, as a familiar ornamental water-garden sedge.

The Zambezian coastal flooded savanna is restricted to the coastal lowlands of Mozambique, comprising the floodplain deltas of the Zambezi, Pungwe, Buzi, and Save rivers, with the vast Zambezi delta stretching nearly 200 km along the Indian Ocean coast and reaching up to 120 km inland. It is a mosaic of seasonally flooded grasslands and savanna interwoven with mixed freshwater swamp forests, whose plant communities shift with soil type and flooding duration: reed swamps of Phragmites and Typha, grasses such as Hyparrhenia, Ischaemum, and Setaria, and scattered trees and palms including Parinari, Uapaca, Syzygium, and Borassus. Rainfall is strongly seasonal, with most of the roughly 800 to 1,400 mm falling between October and March, and the river-driven flood pulse governs which habitats develop. The wetlands hold the highest concentration of waterbirds in Mozambique and are a stronghold for the wattled crane, the ecoregion's flagship species, with portions protected within the Marromeu National Reserve and Gorongosa National Park. For gardeners, several striking palms are native here, among them the wild date palm (Phoenix reclinata) and the fan palm Hyphaene coriacea.