Biodiversity in the Basin

Definition of Biodiversity

The word biodiversity, a contraction of the synonymous phrase Biological Diversity, is defined by the Convention on Biological Diversity (CBD) as ‘the variability among living organisms from all sources including, inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems’. This is the definition used throughout this document.

Source: CBD 2010a

While biodiversity is relatively high in the Limpopo River basin, there are two specific areas referred to as Biodiversity Hotspots:

Coastal Forests of Eastern Africa
Maputoland-Pondoland-Albany

These 2 hotspots are primarily coastal, but the Maputoland-Pondo-Albany reaches several hundred kilometres inland from the coast to the northern Drakensberg/Strydpoortberg area. This hotspot flanks the Great Escarpment, stretching along the coastline of eastern South Africa from Port Elizabeth to the Limpopo River mouth. The Coastal Forests of Eastern Africa reaches from Somalia, in the Horn of Africa, all the way down the east coast of Africa, also ending at the mouth of the Limpopo River at Xai Xai.

The map below shows the distribution of these two hotspot areas in relation to the entire basin.

Coastal Forests of Eastern Africa

Though tiny and fragmented, the forest remnants that make up the Coastal Forests of Eastern Africa contain remarkable levels of biodiversity. The 40,000 cultivated varieties of African violet, which form the basis of a US$100 million global houseplant trade, are all derived from a handful of species found in the coastal Tanzanian and Kenyan forests.

This hotspot is also home to a variety of primate species including three endemic and highly threatened monkey species and two endemic species of bushbabies. The Tana River, which runs through Central Kenya, is home to two critically threatened and endemic primates, the Tana River red colobus and the Tana River mangabey. Agricultural expansion continues to be the biggest threat facing the Coastal Forests of East Africa. Due to poor soil quality and an increasing population trend, subsistence agriculture as well as commercial farming continue to consume more and more of the region's natural habitat.

Source: Conservation International 2010

Maputoland-Pondoland-Albany

Maputaland-Pondoland-Albany, which stretches along the east coast of southern Africa below the Great Escarpment, is an important center of plant endemism.

The region’s warm temperate forests are home to nearly 600 tree species, the highest tree richness of any temperate forest on the planet. The celebrated, bird-of-paradise flower is a distinctive hotspot endemic. The rescue of the southern subspecies of white rhinoceros from extinction, which took place in this hotspot, is one of the best-known success stories in African conservation.

Regrettably, much of the once expansive grasslands and forests in which many of the large mammals dwell is facing increased threats from industrial and local farming and also the expansion of grazing lands.

Source: Conservation International 2010

Last of the Wild

Following are a series of maps developed by the Socioeconomic Data and Applications Centre (SEDA)at Columbia University related to the influence of humans on biodiversity and the landscape. The maps presented include the following:

Human Influence Index;
Human Footprint Index; and
Last of the Wild.

Human Influence Index

The Human Influence Index measures the direction impact of human beings and their activities on terrestrial ecosystems using 8 measures:

Human settlement
- Population density
- Built-up areas
Access
- Roads
- Railways
- Navigable rivers
- Coastline
Landscape transformation
- Land use/land cover
Electrical power infrastructure
- Night time lights

Human Influence Index ranges from 0 (no human influence) to 64 (maximum human influence. Human Influence is highest in the western basin, must influenced by urban settlements and agriculture in the broad strip of land from Johannesburg, north into Zimbabwe. The eastern basin remains relatively uninfluenced, with broad areas of land in the Lower Limpopo and Changane sub-basins with little influence at all.

Last of the Wild

The Last of the Wild is intended to highlight the remaining areas of intact 'wild' land, or un-impacted biomes. This is defined as the parts of the landscape with values of less than 10 in the Human Footprint Index. The map shows the extent of the un-impacted biomes. The two biomes in the basin that are highlighted are: