Land Use Patterns and Practices
Water erosion and reduced soil conservation in semi-arid Burkina Faso negatively affects ecosystem services
Land use changes are responses to changes in the provision of ecosystem services, and they also cause changes in this provision. Historically, dryland livelihoods have been based on a mixture of hunting, gathering, cropping, and animal husbandry. This mixture varied in composition with time, place, and culture. The harsh and unpredictable climate combined with changing socioeconomic and political factors has forced dryland inhabitants to be ﬂexible in land use. Population pressure, however, has led to a growing tension between two main land uses: pastoral rangeland and cultivated land use. In some areas, this led to intercultural conﬂicts and desertification as herders and farmers claim access to and use of the same land. In other cases, it led to synergistic interaction and integration between the two land uses, with herders cultivating more land, farmers holding more livestock, and an increased exchange of services between the two groups. The synergistic behavior among pastoralists and farmers is driven by both governmental policies and favorable market opportunities; the two groups cooperate when it is in their own vested interests (see Key Question [How can we prevent or reverse desertification?]) (C22.5.1).
Irrigation has led to increased cultivation and food production in drylands, but in many cases this has been unsustainable without extensive public capital investment. Large-scale irrigation has also resulted in many environmental problems— such as waterlogging and salinization, water pollution, eutrophication, and unsustainable exploitation of groundwater aquifers—that degrade the drylands’ service provisioning. In such irrigation approaches, rivers are often disconnected from their ﬂoodplains and other inland water habitats, and groundwater recharge has been reduced. These human-induced changes have in turn had an impact on the migratory patterns of fish species and the species composition of riparian habitat, opened up paths for exotic species, changed coastal ecosystems, and contributed to an overall loss of freshwater biodiversity and inland fishery resources. On the whole, there is a decline in biodiversity and services provided by inland water systems in drylands, which further exacerbates desertification (C20.ES).
Frequent and intensive fires can be an important contributor to desertification, whereas controlled fires play an important role in the management of dryland pastoral and cropping systems. In both cases, the use of fire promotes the service of nutrient cycling and makes nutrients stored in the vegetation available for forage and crop production. For example, dryland pastoralists use controlled fire to improve forage quality, and dryland farmers use fire to clear new land for cultivation. Conversely, fires can be an important cause of desertification in some regions when they affect natural vegetation. Excessive intensity and frequency can lead to irreversible changes in ecological processes and, ultimately, to desertification. The consequences of such changes include the loss of soil organic matter, erosion, loss of biodiversity, and habitat changes for many plant and animal species (C22.3.3, C22.4.2, C22.5.1).