The miombo woodlands are a vast tropical savanna ecosystem covering much of central and southern Africa. Characterized by specific tree genera and an ecological dynamic shaped by seasonal changes and natural occurrences, these woodlands provide resources and services, supporting local communities and broader environmental processes.
Geographic Reach and Defining Features
Miombo woodlands span south-central Africa, from Angola in the west to Tanzania in the east, encompassing parts of the Democratic Republic of the Congo, Malawi, Mozambique, Zambia, and Zimbabwe. This extensive coverage makes them the most widespread dry tropical forest type globally, covering approximately 1.9 million square kilometers.
The woodlands are characterized by semi-deciduous trees from the legume family, specifically Brachystegia, Julbernardia, and Isoberlinia genera. These trees shed their leaves during the dry season to minimize water loss. Before the wet season, they produce new leaves displaying vibrant gold, red, and coppery hues, reminiscent of autumn colors.
Miombo woodlands have an open canopy, with dominant trees reaching 10-20 meters, and a continuous grassy understory. The ecosystem experiences a seasonal tropical climate, with most rainfall from November through March, followed by a cooler dry season lasting up to six months. Annual rainfall ranges between 600 and 1,000 millimeters, though some areas receive over 1,000 millimeters, leading to classifications of dry or wet miombo.
Natural fires are a component of the miombo ecosystem, periodically sweeping through the woodlands. This disturbance helps maintain a balance between trees, shrubs, and grassy patches, as many miombo species tolerate fire. Trees often resprout from their stumps after fire or harvesting, demonstrating resilience.
Life Within the Woodlands
Miombo woodlands support diverse flora and fauna adapted to this environment. Beyond dominant tree genera like Brachystegia and Julbernardia, the understory hosts various plant species, including orchids and fungi. The Zambezian region, including miombo, is a center of plant endemism, with an estimated 8,500 higher plant species, including 334 tree species. Over half of these tree species are unique to this biome.
The woodlands provide habitat and sustenance for many animal species. Large mammals like the African elephant (Loxodonta africana), African wild dog (Lycaon pictus), sable antelope (Hippotragus niger), and Lichtenstein’s hartebeest (Sigmoceros lichtensteinii) are characteristic inhabitants. Many species rely on non-miombo vegetation within or adjacent to the ecoregion for food, water, or shelter during droughts and frequent fires.
Birdlife is rich in the miombo, with many species adapted to its conditions. Examples include the miombo rock thrush (Monticola angolensis), red-capped crombec (Sylvietta ruficapilla), and miombo pied barbet (Tricholaema frontata). While bird species richness is high, only a few, such as Stierling’s woodpecker, are near-endemic. Insects are also part of the woodland’s web of life, though their activity may diminish during the dry season.
Ecological Role
Miombo woodlands perform ecological functions influencing regional and global processes. They serve as carbon repositories, storing carbon in woody vegetation and soil. Estimates suggest woody biomass stores between 18 and 24 petagrams of carbon, evenly distributed between soil and vegetation. Soil organic carbon stocks can account for 50-80% of the total carbon stored in the ecosystem.
The woodlands regulate regional hydrology and rainfall patterns. They contribute to water flow regulation and influence water sources important for agriculture and hydropower generation. Research on the link between miombo’s hydrological function and human well-being is developing, but the trees’ access to deeper soil moisture likely makes them important for water cycling.
Beyond carbon and water, miombo woodlands contribute to soil protection and nutrient cycling. They stabilize soils, reducing erosion, and facilitate nutrient movement, which supports regional agriculture. Woodlands make nutrients available for crop production through processes like woodland-field lateral transfers and shifting cultivation, reducing the need for chemical fertilizers on inherently infertile soils. These functions support a broad array of life and contribute to ecosystem health.
Human Connection and Pressures
Local communities across central and southern Africa depend on miombo woodlands for their livelihoods. These woodlands provide resources, including timber for construction and non-timber forest products such as fruits, honey, and mushrooms. Fuelwood, especially charcoal, constitutes a substantial portion of regional energy use; about three-quarters of energy consumption in miombo regions comes from these woodlands.
Despite their importance, miombo woodlands face pressures contributing to their degradation and loss. Agricultural expansion, driven by population growth, is a primary cause of deforestation, as land is cleared for subsistence and commercial farming. This involves practices like slash-and-burn agriculture, where woodlands are felled and burned to prepare land for staple crops such as maize and sorghum.
Charcoal production is a major driver of deforestation and forest degradation, especially in areas with inadequate electricity supply. Increasing urban demand for charcoal, fueled by population growth and urbanization, places pressure on the woodlands. For instance, in Lubumbashi, Democratic Republic of Congo, charcoal is the primary domestic energy source for over 72% of households, leading to a loss of miombo woodland at an annual rate of about 1.51% between 1990 and 2022.
Illegal logging also contributes to the decline of miombo woodlands, targeting valuable timber species like mninga and African blackwood. Climate change further exacerbates these pressures by altering fire regimes and increasing drought frequency and severity. These environmental changes can shift the distribution and composition of plant and animal species within the miombo ecosystem. Efforts to promote sustainable land use practices and improve forest governance are underway to maintain the ecosystem services and livelihoods provided by these woodlands.