PMC

Wood-fuel harvesting is sustainable when (a) the rate of wood growth exceeds (b) the rate of wood use. The predicted areas with adequate supplies and shortage for the year 1995 are shown in (c) ().

The location of assessment sites in the Southern African Millennium Ecosystem Assessment (SAfMA) which approximates the greater South African Development Community (SADC) region. The inset (upper right) shows the nested assessment design ().

The effect of increasing land use intensity on the fraction of the inferred original population (300 years ago: pre-colonial) of different taxa that remains. The x-axis percentages refer to the percentage of southern Africa under the respective land uses (see ). Human landscape modifications can also lead to increases of populations under conditions of light use (see amphibians).

In the Great Fish River Valley in South Africa, the perception of a local community about water quality varies with land ownership. The local community has experienced a decrease in the quality of water on community land, but believes that water quality on state land has remained constant. Scores 0–10 (y-axis) reflect the relative weights placed on water quality declines by the community in a participatory process (see ).

(a) The important crop production areas of the Gariep basin in South Africa expressed in terms of the recommended daily allowance (RDA) of cereal consumption (220 kg/person/yr) and the location of Gauteng urban industrial complex. (b) The ratio between food consumption and production in the Gauteng Province of South Africa, where only intensive chicken production marginally outstrips the local demand ().

Role of scale in the assessments of water supply and demand differences in Africa (a) regional scale, (b) Gariep basin scale and (c) regional scale in the driest month of the year (m³/ person/year). Water is unevenly distributed in the southern African region, and this ‘lumpiness’ is apparent at multiple scales. When one zooms in on an area that appears uniform at the regional scale, localized areas of excess and deficit appear. Assessments at more detailed scales, such as the Gariep basin assessment, tend to use localized datasets (e.g. national statistics), and often give results that differ significantly from those derived from larger scale studies that use global or continental datasets ().

Ecosystem service and human well-being ‘hotspots’ in the Gariep basin are areas where service provision or human well-being may be of concern. These ‘hotspots’ incorporate supply-side and demand-side considerations. Shaded areas indicate areas (from top to bottom) (a) where surface water requirements are 60% or more of availability (m³/person/year) per quaternary catchment, (b) where electricity is supplied by a local authority to 25% or fewer of households per municipal district (Lesotho=national figures) and (c) of high income inequality per municipal district (Gini index above 0.85; ). The Gini index quantifies the relationship between the income generated by different proportions of the human population. A value of 0 would indicate an equal income distribution and a value of 1, a highly skewed income distribution with few people procuring most of the income.

Irreplaceability maps for the Gariep basin based on (a) recommended daily allowance targets for proteins: 60 kg/person/year×population size, (b) recommended daily allowance targets for cereal consumption: 220 kg/person/year×population size and (c) combined mammal and bird species (one representation each) and vegetation targets (10% of each vegetation type). The algorithm selected the minimum area required to achieve the respective targets and would therefore initially select high productivity areas. Irreplaceability values range from 0 (very low importance for achieving target and many options for substituting cells with other cells to achieve target) to 1 (totally irreplaceable: if this cell were not included in the provision of services, the goals for those services could not be met; ).