Colombo's bio-diversity - richest of Asian cities

by Sajitha Prematunge

The city of Colombo. What comes to mind, a concrete jungle? But if you look a little closer you'll find much more. Did you know that an amazing 55 species of birds, 165 species of woody plants, 20% of all woody plants in Sri Lanka and 16 species of butterflies have been recorded from various urban refuges.

An Urban Biodiversity Survey conducted by IUCN The World Conservation Union shows that urban areas house an abundance of birds, butterflies, woody plant, small mammals and insects. The pressure on the environment by an ever increasing population is on the rise. With only 10 to 15% of natural and semi natural habitats remaining in the world, it is a comfort to think that urban areas are not the typical concrete jungles we expect it to be.

In fact you might find some really unexpected places in the list of sort after urban refuges. The most unpredictable of all may be the Borella Cemetery. Other than serving as a peaceful resting place for the dead, the Borella Cemetery is home to an array of wildlife such as herpetofauna, small mammals and large numbers of avi fauna such as the Flying fox and Common Mynah.

Although they were not sampled for the survey, they were in such abundance that it caught the attention of even the researchers. Among the much larger urban refuges are the Royal Golf Course, the Colombo University premises and the Viharamahadivi Park.

The Royal Golf Course consisting isolated trees and grass lands, has proven to be an ideal place for 'urban wildlife'.The Colombo Cathedral, next to BMICH, is significant not only for its' beautiful grounds but also for the wildlife it sustains.

The University of Colombo is found to have the second highest diversity of trees and woody plants (102 species). Many different trees from around the country have been introduced to the Viharamahadevi Park such as Banyan and Bedi Del. In fact the most number of woody plants, 115 species, were recorded at the Viharamahadevi Park, including endemics.

This is an ideal roosting site for the Giant Fruit Bat, large colonies of Flying fox and the very common House crow and the jungle crow. The ponds are home to many other aquatic birds.

The Beira Lake is one of the best urban refuges for aquatic birds. carnivores such as Pelicans, King fishers and Sea Eagles are a frequent site at the lake. The wayside of Colombo 3 and 7 is conspicuous for avenue plantations like Banyan and Mara trees.

These trees are key stone species, and many other species flora and fauna alike, are associated with them. It's home to many species of epiphytes such as lichens, orchid species namely Cymbidium sp. and serves as a roosting site for many bird species such as the Common Mynah.

Highly rated

Compared to the rest of the city, Colombo has the richest bio-diversity, with its' well kept home gardens, lawns and many flowering plants. Although comparatively the human density in Colombo is higher than in other Asian cities the survey shows that it's also richer in biodiversity compared to other Asian cities.

As we all know living in a concrete jungle can be highly stressful. So protecting these little patches of green and the host of species they house is crucial. Ecologist, IUCN Dilup C. Perera told the Sunday Observer that although places like the Viharamahadevi Park may not be as rich in biodiversity as a tropical rain forest, it's as near as we can get to it in a city.

It has a vast recreational and aesthetic value. Dr. Channa Bambaradeniya Suggested that the Urban Development Authority should safeguard sites like these as recreational sites.

Urban areas give rise to many modes of pollution, and air pollution is one of the most common. Carbon dioxide, methane and Green House Gases (GHG) are emitted from various sources such as vehicles, factories, air conditioners, etc... A place with a sufficient vegetation cover, such as the Viharamahadevi Park, would be quite efficient at Carbon sequestrating and air purification in general.

Green areas are also good micro climate stabilizers, since it reduces temperature and provides shade. These green areas can also serve as laboratories for learning. The grounds of Royal College is the best example. It sustains many species of butterflies, birds and trees. This is an ideal site to create environmental awareness in the young mind.

Green areas add to the scenic value and reduces visual pollution. fortunately the latest trend of putting up display boards and billboards in front of trees, obscuring their beauty has caught the attention of the urban councils. But unfortunately the littering of urban refuges still go unnoticed.

The visitors who come to parks like the Viharamahadevi, litter it with non-biodegradable waste such as plastic cups, polythene bags etc...Proliferation of opportunistic animals is another problem faced by parks of Sri Lanka, which is also caused by such littering.

Specially the two types of crow attack the other birds such as Flying foxes. Feral dogs can be a nuisance to both the visitors themselves and other resident animals. One of the suggestions in the survey report is to establish an awareness centre in the Viharamahadevi park Wetlands play an important role in the protection of the urban communities.

These important eco-systems also act as flood retention centres. All the access water is transmitted to wetlands like the Beira Lake and access rain water is soaked up by such places as play grounds, parks and cemeteries.

In urban areas most of the ground is paved or covered with buildings where access water cannot be absorbed. Lack of open spaces could mean flash floods. But unfortunately the current situation of the wetlands and marshes in Sri Lanka is pathetic. Raw sewage, oil and harmful chemicals from factories, and house hold waste have lead to the eutrophication of the Beira Lake.

Major problem

Dilup C.Perera stated that soil erosion is the major problem mostly associated with urbanization and over population. Trees are cut for various industrial purposes, to make way for agriculture or construction of houses.

The best way to combat this is to replant urban areas. Grasses can be used as carpets to prevent soil erosion in open spaces and herbaceous plants in avenue plantations. Native species should be introduced as much as possible, because exotic species can be harmful to the existing ecology of the area. Invasive alien species like Mahogany is the best example.

Because it's an alien and don't have natural threats, these species grow rapidly and become a hazard to the indigenous species of the area. Any sort of replantation process should be well planned, explained Dilup C.Perera.

Aquatic alien invasive species also pose a threat to the urban wetlands. Due to the eutrophic conditions of the lakes like Beira, species such as Salvinia, Water Hyasinth blanket the lake. In land the most troublesome invasive species are Lantana and Guinee Grass.

Dr. Channa Bambaradeniya, Coordinator Asia Regional Office, Species Conservation. said that urban refuges should be preserved not just for the rich biodiversity it sustains, but also for the sake of urban dwellers. Although Sri Lanka is not categorized as a developed country, it's already following suit in vertical development.

Already a skyline is gradually forming itself above Colombo. At an age when real estate prizes are sky rocketing and space itself is diminishing at an alarming rate, vertical development maybe the only solution. But human unrest will not be too far behind.

Developed countries use roof-top gardens as a remedy, of which air purification and aesthetic beauty are added advantages. The west also develop cemeteries in to biodiversity refuges to the point that they don't even seem like cemeteries any more.

The same can be done to cemeteries like the Borella Cemetery. Cultural diversity is another important aspect of biodiversity. Culturally important sites such as the Kotte Marshes and Bellanwila-Aththidiya Marshes are significant for both their biodiversity as well as their cultural diversity.

More and more people migrate to the cities every day in search of job opportunities. The end result is ribbon development - the formation of haphazard constructions like shanties and slums too close to urban refuges. They are not dedicated to follow conservative methods, such as proper garbage disposal, due to their ignorance. The effects of ribbon development on urban refuges is strikingly evident in the Beira Lake.

Of course there are definite economical advantages to saving these marvellous refuges. An economical evaluation of Muthurajawela marsh conducted by the IUCN (Assessment of Economic Value of Muthurajawela Wetlands, 2003) shows that if not for the Muthurajawela Marsh, the government would have had to spend a lot of money on flood control.

This is both economically and ecologically friendly. For example take an air conditioned room and a room with good natural air circulation and surrounding trees. Given the choice people might settle for the natural eco-friendly, wallet-friendly way.

Another very viable economical venture would be to impose taxes or issue tickets for using recreational areas. If funds are a constraint the private sector would probably be more than willing to lend a hand in saving urban biodiversity refuges of such national significance.

Developing urban areas as refuges don't mean we have to discard the protected areas, but whether we like it or not natural habitats are diminishing fast and with the increasing population and the on going development process only so much of the country can be designated for protected areas.

But maintained in such a way urban areas can provide the habitats for many species and some species will always adapt whatever metamorphoses takes place.

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