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5.2: Drivers of Habitat Loss and Fragmentation

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  • At present, Africa’s biggest driver of habitat loss is agriculture (Potapov et al., 2017). African farmers have always cleared lands to meet their subsistence needs. Much of this clearing was traditionally and historically done in the form of slash-and-burn agriculture (also called shifting cultivation, Figure 5.4). To prepare land for crops, smallholder farmers would first cut down trees to clear the land and to obtain fuel wood. The remaining vegetation would then be burned away to release carbon and other nutrients, which increases land fertility. Farmers would grow crops on these cleared areas for two or three seasons. Then soil fertility would diminish, crop production would decline, and the farmers would abandon the area and clear new land, giving the natural ecosystem on the abandoned land time to regenerate.

    Fig_5.4_NASA-2.jpg
    Figure 5.4 On a cloudless day, multiple fires raging in Mozambique’s Zambezi River delta region can be seen from the International Space Station. Slash-and-burn techniques are often used to clear natural ecosystems for grazing and crops. Overly frequent fires, however, do not allow for ecosystem recovery, and are devastating to fire-sensitive ecosystems, such as tropical forests; instead of recovery, every fire creeps deeper and deeper into the forest until the entire ecosystem has been degraded. Image by NASA, https://commons.wikimedia.org/wiki/File:Zambezi_delta.jpg, CC0.

    Medical and technological advances, and the arrival of colonists, saw Africa’s human population grow considerably since the 1800s. Feeding and accommodating the activities of this growing human population saw an increasing number of natural ecosystems replaced by agricultural land, and less area given the time to regenerate. An increasing number of people also started abandoning their rural subsistence lifestyles for cities in search of jobs, financial freedom, and an easier life. As urbanisation increased (i.e. more people moved to cities) and competition for jobs intensified, an increasing number of city dwellers became dependent on collecting charcoal for cooking and cultivating cash crops, such as yams and cassava (Rudel, 2013). This saw even more natural ecosystems converted, particularly on the outskirts of cities. In the meantime, the remaining rural population became increasingly sedentary due to changing land tenure systems, which forced them into unsustainable farming practices as competition for land increased. These factors not only increased rates of habitat loss, but also changed the nutrient content in the soil which, in turn, reduce the land’s ability to regenerate and to produce food (Drechsel et al., 2001; Wallenfang et al., 2015) which, in turn, leads to even more land clearing for agriculture.

    While land clearing for smallholder agricultural needs continues to be an important driver of habitat loss (Tyukavina et al., 2018), its impact is increasingly dwarfed by the demands of commercial interests (Austin et al., 2017). The impact of land grabbing is of particular concern. Foreign companies from Asia and other parts of the world have acquired millions of hectares of land across Africa to stake a claim on the continent’s rich natural resources, and to produce food and biofuels for their own people (von Braun and Meinzen-Dick, 2009). The foreign stakeholders, who often strike these land deals through loan agreements at the governmental level (i.e. with little to no local input), typically prioritise their own needs and profits over local interests with little care for the environment. These deals thus often end with a country saddled with debt they struggle to repay, and environmental damage that will take generations to reverse. Moreover, the foreign companies often employ migrant labourers with fewer protections and rights, compared to local peoples. In the process, while a modest number of local people may benefit from job creation, technology investment, and infrastructure development, a large number of local people become disenfranchised and displaced from the lands that previously supported their livelihoods. These foreign investments are a type of neocolonialism for their resemblance to Africa’s earlier colonial era. They not only drive large-scale habitat loss, but in many instances also leave local people impoverished and desolate (Koohafkan et al., 2011).

    The impacts of land clearing for smallholder farms are increasingly dwarfed by the outsized demands of commercial interests.

    To understand the impact of land grabbing on Africa’s natural environment, one simply needs to consider their scale. For example, Chinese bioenergy producers recently secured over 48,000 km2 of land in the DRC and Zambia (Smaller et al., 2012). Another deal, between the Ethiopian government and companies from India and Saudi Arabia, saw 5,000 km2 of land (including sections of Gambella National Park) earmarked for commercial agriculture. At the time, this Ethiopian deal threatened both the second largest mammal migration on Earth (Ykhanbai et al., 2014) and the livelihoods of the local pastoralist Anuak community (Abbink, 2011). Fortunately, the Ethiopian government and developers were responsive to concerns raised by conservationists and human rights advocates, and agreed to set some areas aside for conservation, while also putting measures in place to maintain free movement of animals and pastoralists.

    Infrastructure developments are also becoming an important driver of habitat loss. Offering access to previously unexploited areas, roads are perhaps the single biggest driver of habitat loss facing Africa’s last remaining wildernesses (Figure 5.5). As prominent tropical biologist Bill Laurance eloquently noted, “Roads usually open a Pandora’s Box of environmental problems—such as illegal fires, deforestation, overhunting and gold mining” (Laurance et al., 2014). A vast, growing body of literature from Africa supports these claims. For instance, research in the Congo Basin has shown how deforestation generally occurs within 2 km from roads (Mertens and Lambin, 1997)>—more roads thus mean more deforestation. Roads also facilitate other drivers of forest loss, including the spread of invasive species, human settlements, fire, and pollution (Kalwij et al., 2008; Potapov et al., 2017). Providing access points for hunters, roads also facilitate unsustainable hunting; a recent review found that the wildlife reductions due to hunting could be detected as far as 40 km from the nearest road (Benítez-López et al., 2017).

    Fig_5.5_Doumenge-2.jpg
    Figure 5.5 New road developments, such as this one in the Congo Basin, represent one of the most immediate threats to biodiversity conservation. Road development provides access to previously unexploited areas, allowing more areas to be hunted, logged, farmed, and settled; increased human activity also exposes these areas to invasive species and pollution. Photograph by Charles Doumenge, https://www.flickr.com/photos/internetarchivebookimages/20689353531, CC0.
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