Windhoek — 2010 is biodiversity year. The City of Windhoek has commissioned a study to ascertain how developments are threatening its biodiversity.

A principal conclusion to an inventory of Windhoek's biodiversity is that the city's rich natural environment is at risk of rapid degradation and in some areas, even collapse.

This is based on a study 'Windhoek Biodiversity Inventory' commissioned by the city to Enviro Dynamics, a local environmental management consultancy, and presented to a public forum last week.

The purpose of the presentation was to establish a partnership between the city management and a working group consisting of members of the pubic.

It is realised that biodiversity - or biological wealth - particularly in urban areas is taken for granted, with less emphasis thereon while there is often an over-emphasis on other considerations such as material and cultural wealth.

Experts think this is a major strategic error, precisely because natural systems support economies, lives and livelihoods.

The United Nations has declared 2010 the International Year of Biodiversity. Its theme is 'biodiversity, development and poverty alleviation: recognising the role of biodiversity for human wellbeing'.

Enviro Dynamics said the loss of biological diversity - or biodiversity - is probably one of the world's most serious problems with resultant growing concern over the status of biological resources.

Biodiversity refers to the variety of all living organisms, including vegetation and animals. It forms the living lifeblood of all existence.

In urban centres in all developing countries that now experience growing populations and increased settlement densities, biodiversity is threatened.

More pressure is placed on available natural resources, on the integrity of eco-systems and biological diversity.

"Windhoek is no exception," said Enviro Dynamics.

The purpose of the inventory commissioned at the beginning of 2009 and finalised at the end of last year, was done because the environmental management division of the City of Windhoek lacked sufficient data and research on biodiversity.

It was thus difficult for the city management to direct sustainable development and conservation initiatives.

The study has divided Windhoek and Windhoek townlands into six habitats according to the city's environmental structure plan.

The habitats identified were open water areas, riverine thickets, the Windhoek valley, high mountains, the Khomas Hochland Brokenveld and the urban semi-natural (where lower density development occurs with lots of open spaces and recreational grounds), and urban unnatural spaces (built up areas).

The specialist study focused on each of the habitats to determine the total diversity of each, the diversity of species within these, the number of species per square kilometre, their conservation status in protected areas and especially protected species, the (International Union for Conservation of Nature) IUCN list status, and the known threats to these.

All species of conservation concern were weighted. The total sensitivity for each habitat in terms of conservation status was determined, and future conservation areas were determined.

Furthermore, areas threatened by Windhoek's existing and future development were determined by overlapping sensitivity maps with the Windhoek structure plan information, which Enviro Dynamics environmental consultant, Stephanie van Zyl, said is more than 10 years old.

- Open water areas

In the Windhoek townlands, two open water areas were considered - the Goreangab and Avis dams, which, according to Enviro Dynamics, are crucial contributors to bird biodiversity.

The major threats to these areas are pollution, as a result of industrial and urban wastage, and agricultural management practices.

More pressure is placed on these due to alien aquatic species - like carp - that places strain on naturally occurring organisms. Endemic species like the Manulea dubia, were shown to be under threat due to alien vegetation.

Twenty-nine vegetation species were identified, 112 insect species, 196 bird species (all of whom are considered protected), six amphibian types, and one reptile species. Five alien invasive vegetations were identified.

One insect species and four bird species were found to be "near threatened" and vulnerable with a high risk of extinction.

One bird species was found endangered.

- Riverine thickets

These include the thick riparian vegetation that characterises the ephemeral watercourses that criss-cross the city landscape. However, it excludes the flat, silt-like, alluvial plains characteristically lined with camel thorn trees. It does involve the dry riverbeds and riverbanks.

Enviro Dynamics said the riverines provide stability and protect riverbanks from erosion. They further protect the alluvial plains and lowlands next to the rivers from erosion.

"Erosion channels with the alluvial plains increase the speed of water run-off through canalisation and put the eco-system function of water infiltration into the aquifer at risk," said Enviro Dynamic.

Threats to the Gammams and Klein Windhoek rivers that were found are alien vegetation, mining, roads constructed in such a way that the natural flow of the river is altered, de-forestation, canalisation, dumping and litter, fires, sewerage, encroachment and erosion.

At the riverine thickets, 119 different vegetation types were found, no species of insects were listed, 96 species of birds, eight amphibian species, 62 reptile species, and 26 mammal species were also found.

Twenty-eight alien vegetation and one mammal species were listed.

Four bird and two mammal species were found "near threatened", one mammal species was found vulnerable and four bird species are endangered.

Threats to these habitats are the over-harvesting of the camel thorn tree; a loss of woody species; encroachment and canalisation of riverbeds.

"The best thing is to keep development away from rivers and to protect the riverbanks," said Van Zyl.

- Windhoek valley

Much of Windhoek lies within a valley surrounded by mountain ranges. Acacia mellifera shrub land and dense grass cover dominate the lowlands.

Degradation of these areas leads to reduced grass cover, which results in faster run-offs of water and thus less water infiltration.

Van Zyl said this area is mostly targeted for development because of its favourable slope, and hence more vulnerable than the other habitats.

But, said Van Zyl, because of this, there is a danger that the entire area's biodiversity can be lost if insufficient consideration is given.

"Biodiversity is, in fact, an asset for development; it makes for a more attractive environment, it is good for the wellbeing of people. Developers are not sensitive to this at all," said Van Zyl.

The biggest threat is the urban sprawl that causes destruction and fragmentation to the habitats, she said.

And so is overgrazing and habitat destruction on many of the commonage farms - which are properties of the City of Windhoek - leading to the depletion of biodiversity in adjacent areas.

The study found that in this area, live trees are chopped down or ring barked; there is pollution due to industries close to the Brakwater area like the tannery and the power station; the expansion of informal settlements especially in northern Windhoek; and illegal harvesting of wood.

Van Zyl said notwithstanding the large influx in northern lying informal settlements, it is not clear whether unchecked development or urban sprawl cause more harm.

"There are speculations as to which of these has the most impact," she said.

But the fact remains that the Windhoek valley is most threatened, and needs focus, she added.

In this area, 172 vegetation species were found; 130 different types of insects, 159 bird species, 10 types of amphibians, 67 different kinds of reptiles, and 69 different types of mammals. Twenty-two species were found threatened or vulnerable, and seven bird species are endangered.

- High mountains

The mountain ranges covered by the study include the northern slopes of the Auas range, the Kaiser Wilhelm Berg, and the highest reaches of the Eros range.

Threats identified here are roads and other infrastructure that increase the risk of erosion;

telecommunications towers endangering birdlife; overgrazing on slopes; and urbanisation and development that destroys and fragments the natural habitat.

A positive development, though, is that Windhoek's structure has a southern development limit, which means that no development is allowed beyond the southern line that borders Luiperts valley.

This, however, means that most development takes place northwards towards the Brakwater area.

This area is rich in plant and animal species, 11 of which are threatened and vulnerable. Seven bird species are endangered.

- Khomas Hochland Brokenveld

This area forms the transitional zone between the eastern highlands and the desert plains in west Namibia. It includes the Eros Mountains north-east of Windhoek and most of the south-eastern and south-western parts of the city.

It forms rocky outcrops where the soils are shallow and susceptible to erosion.

The threats here are deforestation, uncontrolled tourism activities; dumping of waste in unauthorised places, unseasonal fires, agricultural activities, and alien invasive vegetation.

It has seven endangered bird species; the brown hyena found here is also endangered.

- Urban semi-natural and urban unnatural areas

The biggest threats in these areas is the removal of natural debris like fallen trees and leaves, the introduction of alien vegetation in green areas, and the loss of river connectivity.

So, for example, said Van Zyl, Windhoek's planning scheme prohibits the growing of prosopis trees - an invasive species that chokes other natural vegetation and spreads its seeds in river systems.

What makes it worse, she said, is that many of the invasive tree species do not provide shelter to the local wildlife.

- Recommendations

A major recommendation made by Enviro Dynamics is for city planners to address deforestation with the urgency it requires. Urban green spaces, it said, must be protected.

Furthermore, it suggested that alien vegetation species must be eradicated, while indigenous vegetation should be promoted.

In fact, suggested the study, any city parks developed in future should consist primarily of indigenous vegetation.

It said the Directorate of Forestry should make available a greater variety of indigenous trees, and penalties should be introduced for the removal of large indigenous trees and the total clearing of construction sites.

Policy changes should consider development in riverine thickets; drainage regulations should monitor canalisation; building regulations should consider the natural environment; and lease agreements on commonage farms must be reconsidered.

It further suggested that the City of Windhoek set specific goals to conserve biodiversity, alongside an annual monitoring programme to indicate eco-system health of Windhoek's key riverbeds.

Public awareness is another key area where residents should be sensitised on what to do or what to refrain from. Importantly also, said Van Zyl, is that aware ratepayers can put sufficient pressure on the municipality to take corrective measures.