Population growth (the total population of Durban Metropolitan Area was estimated at 2 523 601 people in 1998), and associated urban development, is the prime cause of reduction of biodiversity in the Durban Metropolitan Area (DMA). Other significant causes include invasion by alien plant species, pressure to meet housing and servicing needs, urban agriculture, muthi plant harvesting, illegal dumping, quarrying and sand mining

Extensive and growing urban development
Extensive urban development in the DMA has resulted in natural habitats being largely replaced with buildings, paved surfaces and exotic gardens. For example, the development of the Durban International Airport and adjacent industrial area resulted in the destruction of extensive wetland areas. Similarly, the development of the Durban Port resulted in the destruction of rich areas of mangroves in Durban Bay.

The pressure of urban development on biodiversity continues to increase. A rapidly growing population has created the need for extensive housing and infrastructure provision. Over a quarter of a million houses must be provided to meet the current housing backlog. These houses will need to occupy large areas of currently undeveloped land. This potentially creates conflict between meeting basic needs of Durban residents and sustaining the city's rich biological resource base.

A rapidly expanding population, coupled with a severe shortage of housing, has led to extensive informal settlement development. In 1997 about 143 000 households were located in informal settlements. Many open spaces have become settled on in an ad hoc fashion. In the process, the land is stripped of vegetation and soon becomes eroded. In steep areas, mud and landslides are common during the rainy season, often threatening lives.

Urban agriculture
Many of the open spaces in suburban and peri-urban areas are actively utilised for small-scale agriculture. Although agriculture retains green open spaces it significantly reduces the natural ecological functioning of areas. Commercial agriculture, primarily sugar cane, which is occurring in the outer areas of the Metropolitan Area also results in the destruction of natural habitats. It can also decrease the land's productivity resulting in eventual development for housing or industry.

Illegal dumps

Garden and household refuse, light industrial waste and other materials are often dumped in unbuilt areas. These areas become unsightly and polluted. This not only prevents people from enjoying the areas but also reduces their ecological functioning and promotes their invasion by alien species.

Quarries and sand mining
The DMA is not endowed with exploitable mineral deposits in the ordinary sense. The needs of a large city for building and construction materials has, however, resulted in the exploitation of sand resources from both rivers and vacant land. The extraction of these materials can result in extensive disturbance of ecosystems and if not rehabilitated appropriately invasion by alien species is promoted.

Muthi harvesting

The intensive harvesting of indigenous plant species for the Muthi Trade has resulted in a significant reduction in plant stocks. Several sought after plant species e.g. wild ginger and pepper bark tree have become extinct outside protected areas in KwaZulu Natal.