|Figure 2s.8: Interlinked stresses on land and water resources|
Although environmental issues have been presented here by theme, it is important to recognize they are inter-linked and that they therefore need to be addressed with an integrated environmental management approach. Figure 2s.8 illustrates links between stresses on land and water resources, others are highlighted below.
Deforestation and loss of vegetation cover increase the risk of soil erosion, which in turn impacts on aquatic and coastal ecosystems through sedimentation and smothering of habitats. This reduces water availability and quality and contributes to coastal erosion, exacerbating the impacts of climate change on freshwater resources and of sea level rise. Deforestation also affects climatic conditions reducing rainfall and run-off at the micro level (thereby also impacting on freshwater availability and aquatic ecosystems) and contributes to global warming and its impacts at the macro level.
Reductions in rainfall (natural or induced through changes such as deforestation) also impact on infrastructure and urban development, particularly on electricity generation in many parts of Africa where hydro-electric power is well developed. Power shortages and poorly developed central power supplies contribute to deforestation by increasing the population's dependence on wood and charcoal for fuel.
Loss of natural habitat because of urban and agricultural sprawl contributes to declines in biodiversity, loss of economic development potential, and support for livelihoods. Endangerment and extinction of certain species (terrestrial, aquatic, and marine) put pressure on other resources as substitutes are sought to meet people's requirements. Changing patterns of resource distribution also affect life cycles of pests and diseases, and may in turn impact on human health, and crop and livestock yields.
Alien invasive plants cause changes to freshwater availability and alter the diversity and abundance of species within ecosystems. Aquatic weeds also change water quality by adding or removing nutrients and thus affect drinking water quality and human health.