1.1 Soil erosion challenges in East Africa
The East African region harbours rich natural resources that exist in
sharp contrast across the landscape (Veldhuis et al., 2019). These areas
are populated with varied human and livestock densities and while the
landscape provides many ecosystem services, provision is hampered by
human activity and land degradation that include soil erosion. Climate
changes, ecosystem degradation, biodiversity losses and sociopolitical
pressures all impact development, conservation and livelihoods of
socio-ecological systems of which majority of communities rely on across
the region.
Soil resources in East Africa are being rapidly depleted by erosion,
threatening food-, water- and livelihood security in the region (Wynants
et al. 2019; Cobo et al., 2010; Oldeman, 1991). While soil and land
resources are progressively being depleted the population, with
associated needs for livelihoods, food, fibre, and other resources is
expanding (FAO, 2019). Agricultural intensification and economic
diversification are hampered by a lack of available knowledge, skills
and agricultural technology (Korotayev and Zinkina, 2015) and as a
result, an increasing number of farmers are pushed to seek more land to
establish agricultural operations, causing a marked shift from naturally
vegetated landscapes towards agricultural landscapes (Jayne et al.,
2014; Odgaard, 2002). Policies of sedentarisation, privatisation and
confinement within administrative boundaries have impeded the mobility
of previously nomadic pastoralist communities (Homewood et al., 2004).
Moreover, pastoral communities are also experiencing internal pressures
due to higher livestock and other inequality existing among gender and
other community social groups, rapid changes in herd sizes and stocking
densities (both expansion and contraction), shifts towards the need for
external employment opportunities and increased competition over grazing
resources (Rabinovich et al., 2019; Rufino et al., 2013). A combination
of all these and other factors have led to a tripling of the livestock
numbers in the last 50 years (FAO, 2019) with increasing the local
densities of domestic grazers in many areas, leading to overgrazing and
trampling of the soil (Little, 1996; Ruttan and Borgerhoff Mulder,
1999). Furthermore, the high reliance on natural vegetation as a source
of fuel, construction materials and fodder in both the urban and rural
populations is resulting in substantial exploitation pressures on
forests and woodlands (Hiemstra-van der Horst and Hovorka, 2009). The
conjunction of these multiple pressures has increased rates of surface
runoff, soil erosion, gully incision and downstream sediment transport
(Blake et al., 2018; Vanmaercke et al., 2014; Wynants et al., 2020).
Furthermore, these processes are potentially amplified by natural
rainfall variations (Ngecu and Mathu, 1999) and projected increases in
extreme climatic events e.g. drought followed by extreme rainfall
(Nearing et al., 2004). East-Africa’s environments/ecosystems are highly
dynamic in both time and space, posing substantial challenges to the
communities that are dependent on them and the development of
sustainable land management plans.