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Loss of ecological goods and services
The loss of
open spaces, and the biological diversity which they contain,
can result in the loss of a wide range of ecological goods and
services that they provide. Many of these services, such as
waste treatment, then need to be provided through
artificial means at substantial cost. According to the D'MOSS
Framework Plan, the total replacement value of the services
delivered by open space in the Durban Metropolitan Area (DMA)
is conservatively estimated to be R2.24 billion per annum.
This estimate is based on international findings and excluding
the value of Durban's tourism sector. A comparison between the
1998/99 Durban Metroplitan Council's operating expenditure for
general services, airport, electricity, water, market and
transport (R3.5 billion) and the value of open space services
(R2.24 billion) reveals that open space plays a very
significant role in the day to day functioning of the DMA.
Access to open space services therefore represents an
important and generally undervalued contribution to the DMA
community.
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SERVICES |
ECOSYSTEM FUNCTIONS |
EXAMPLES |
|
Gas Regulation |
Regulation of chemical composition of
atmosphere |
Carbon sequestration, oxygen and ozone
production |
|
Climate Regulation |
Regulation of temperatures |
Urban heat amelioration, wind generation, noise
abatement |
|
Disturbance Regulation |
Regulation of episodic and large environmental
fluctuations on ecosystem
functioning |
Flood control, drought recovery, refuges from severe
environmental events |
|
Water Regulation |
Regulation of water flow |
Capture and gradual release of water by vegetation
for urban use |
|
Water Supply |
Storage and retention of water |
Supply of water by rivers, watersheds and reservoirs
for agricultural, industrial and household
use |
|
Erosion Control |
Retention of soil within an
ecosystem |
Prevention of soil loss by vegetation cover and by
capturing soil in wetlands |
|
Soil Formation |
Soil formation processes |
Weathering of rock by water, accumulation of orgnic
material in woodlands and
wetlands |
|
Nutrient Cycling |
Storage, recycling, capture and processing of
nutrients |
Nitrogen fixation, nitrogen cycling through food
chains |
|
Waste Treatment |
Recovery of nutrients, removal and breakdown of
excess nutrients |
Breaking down of waste, detoxifying
pollution |
|
Pollination |
Movement of floral gametes |
Supply of pollinators for plant reproduction,
including insects, birds and
rodents |
|
Biological Control |
Regulation of animal and plant
populations |
Predator control of prey species - rodent control,
insect control, bat control,
etc. |
|
Refugia |
Habitat for resident and migratory
population |
Nurseries, habitat for migratory birds, regional
habitats for species |
|
Food Production |
Primary production for food |
Production of fish, crops, fruit, etc. bu
non-commercial farming |
|
Raw Materials |
Primary production for raw
materials |
Production of fuel, craftwork materials, fodder
etc. |
|
Genetic Resources |
Unique biological materials and
products |
Genes for resistance to plant diseases, ornamental
species, plant medicines |
|
Recreation |
Providing opportunities for recreational
activities |
Eco-tourism, sport fishing, swimming and other
outdoor recreational activities |
|
Cultural |
Providing opportunities for aesthetic, educational,
spiritual, intrinsic and scientific use of
ecosystems |
Scenic views, environmental education, research
opportunities, sense of place, an attractive living
environment for DMA
residents |
(Source:
D'MOSS Framework Plan, 1999)
Increased
flooding
Unwise planning
decisions in the past, and ad hoc settlement of informal
dwellers, has resulted in many river flood plains being
settled on. In addition, the rapid expansion of the built
'footprint' of the city, with associated removal of vegetation
and hardening of surfaces, has increased the flood peak of
most rivers. These two factors have resulted in significant
loss of life and possessions during high rainfall periods
where flash flooding has become common.
Five rivers (Umlaas,
Umbilo, Mhlatuzana, Amanzimnyama and the Isipingo) in the
Durban Metropolitan Area have been canalised where their
flooding threatens residents. This severely diminishes
the river's natural functioning and flooding often becomes a
greater problem downstream of the canalised section of the
river due to the increased speed of flow caused by the
hardened banks.
Decline in muthi supply
The DMA
forms the hub of an extensive regional Muthi Trade based on the supply
of indigenous plants for medicinal purposes. Intensive
harvesting has resulted in the decline of stocks of many
sought after species. This has in turn
resulted in shortages of products and associated increase in
prices, making indigenous medicine less accessible to the
poor. In addition, the livelihoods of
muthi traders, who are primarily black rural women, is becoming
threatened as available stocks decrease.
Loss of recreational and cultural
opportunities
The loss of open space reduces
opportunities for recreational activities such as ecotourism,
bird watching and sports fishing. It also reduces the range of
cultural experiences available including environmental
education, opportunities for scientific research and the
provision of an attractive living environment and a sense of
place for residents.
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