Flora and Fauna in Cities

Many studies show that some animal and plant species are evolving rapidly to adapt to human environments. Either that, or they perhaps already had adaptations that make them more likely to succeed in cities rather than in their natural environments. Some species have lost their natural environments due to human intervention. Whatever the case may be, human beings need to do more to incorporate nature into their cities. Not just because of their intrinsic value, but also because they are a necessity for our survival. For example, birds keep our urban ecosystems in balance: they scavenge carcasses and recycle nutrients back into the earth and are particularly important for keeping the insect population in check. Trees in urban neighbourhoods have innumerable benefits. Below are a few examples of man-made interventions that have brought in biodiversity.

Benthuizerplas in Zoetermeer, Netherlands 

Benthuizerplas is a lake between the village of Benthuizen and Noordhove, a residential neighbourhood in the North-West of the Dutch city of Zoetermeer. The lake has been designed in cooperation with a group of citizens who have an interest in birds. It merges with the Noordhovense Plas, another small lake, and is separated from the Zoetermeerse Plas, a larger lake by a narrow strip of land. This larger area comprising three lakes was an area from where sand had been retrieved for construction purposes. The excavated area was then designed to form a lake. This is possible in the Netherlands due to the high level of the groundwater. Along with rainwater, the two water sources are enough to keep a lake alive.

In a part of this region, a beach and swimming area for people has been designed. There is also a park, restaurants and other recreational activities. In other sections there are houses with boats abutting the lake. Benthuizerplas, however, was specifically designed for the purpose of bringing birds to the lake.

It was designed by the city, in alliance with the citizens participation group, in such a way that the islands made in the middle of the lake do not coalesce with one another and remain inaccessible to people.

Because of these islands, the lake has brought in one of the largest breeding colonies of a small migratory gull: the Black Headed Gull. Other types of birds also breed there, such as the Common Tern, which is a sea bird, the Greylag Goose, which is a large species of Goose, the Tufted Duck, which is a small diving duck and the Eurasian Bittern, which usually builds nests among the reeds at the edge of the lake. A marshy area has been created in one part of the lake to form a warm protected enclosure for birds in winter.

Retrieving sand for construction and designing a lake in the excavated area is not uncommon in the Netherlands. They result in rich, self-sustaining ecosystems.

Country Parks in Hong Kong

According to the South China Morning Post, a government report in 1960 identified the need for the citizens of Hong Kong for extra space. David Trench, the then governor, invited American conservationist Professor Lee Talbot to visit Hong Kong and plot locations for country parks. After surveying the region, Talbot concluded that the parks would be an important place for Hongkongers to ‘regain equilibrium’. In 1965 Talbot wrote that Hong Kong’s population had increased by more than 600 per cent in the last 20 years and therefore reported a need for open spaces for sport and recreation rather than occupying rural land for more housing. The Country Parks Ordinance was enacted in 1976, largely due to the work of another governor, Murray MacLehose. By 1979, 21 parks had been established and the city’s first long-distance hiking trail, a 100 km-long route was completed and named in MacLehose’s honour.

As per the Agriculture, Fisheries and Conservation Department (AFCD), the Country Parks Ordinance provides a legal framework for the designation, development and management of country parks and special areas. Twenty-four country parks have been designated for the purposes of nature conservation, countryside recreation and outdoor education and 22 special areas for nature conservation. About three-quarters of the land that forms Hong Kong is countryside, covering 443 square kilometres. The planted country parks form an extensive network comprising beaches, mountain ranges with open grasslands, woodlands and reservoirs that were built for fresh water schemes, as Honk Kong lacks fresh water sources. The AFCD manages the parks and is responsible for planting and conserving trees and also for the maintenance of the parks.

Although Hong Kong is small in size, its varied habitats contribute to more than 3000 species of flora and 1000 species of fauna, including over 500 species of birds, insects such as butterflies and dragonflies, fish, reptiles and mammals. 

The Shing Mun Arboretum located in the Shing Mun Country Park has a collection of about 300 plant species. It preserves specimens including the rare and endangered plants of Hong Kong and therefore plays a significant role in flora conservation.

Along nature trails and tree walks, there are on-site interpretative plates for people to identify tree species. AFCD also introduced a mobile application called ‘Country Parks Tree Walks’ and published a book to introduce 96 tree species and other interesting plants in the parks to promote tree conservation. Recreational activities in the parks are very popular amongst all sections of society. An outdoor Study Centre was set up at Tai Po Kau, Butterfly Garden at Shing Mun and Ecological Garden at Tai Lam, to bring about more awareness. AFCD also provides conservation education programmes for nature enthusiasts.

Puttenahalli Lake in Bengaluru, India 

Bengaluru, a city known for its many trees and lakes, lost many of them due to urban development and neglect. Lakes reduce the local temperature as well as pollution, raise the water table, form an important habitat for animal and plant life and are a lung space for people. In the absence of a river close-by, Bengaluru depended heavily on lakes for its drinking water requirements. As reported by the Deccan Herald, the 51 active wetlands in 1973 dropped to 17 by 2007, and the number of lakes in Greater Bengaluru came down from 159 to just 93. Some lakes have been converted into residential layouts, bus stands and golf courses, some have been encroached on and some have been used to collect sewage and dump garbage. It has adversely affected the flora and fauna and the number of migratory birds that Bengaluru receives.

The Puttenahalli Lake is 13 acres large, located in J.P. Nagar, Bengaluru. Like other lakes in the city, it was dry and on the brink of extinction. Seeing the lake shrink and the encroachments grow, Usha Rajagopalan, a resident of the neighbourhood, decided to start the ‘Save the Lakes’ initiative resulting in the setting up of the Puttenahalli Neighbourhood Lake Improvement Trust (PNLIT). All the trustees are residents of the neighbourhood, passionate about their cause, with no prior experience with lakes. The restoration process began in 2008 and the trust was registered in 2010. It is the first case in the city where the government has handed over a lake to a trust to officially manage it.

How did they do it?

The process took great patience and perseverance. After writing to the different authorities and talking to the press, they finally won the cooperation of the BBMP (Bruhat Bengaluru Mahanagara Palike), one of the city’s government bodies. The BBMP first fenced the boundary of the lake. The lake bed was then scooped out, a walk-way raised around it and the island around the single remaining wild date palm was shored up.

The PNLIT got the BWSSB (Bengaluru Water Supply and Sewerage Board) to divert sewage water entering the lake into an underground drain. The pools of water that were left behind after this evaporated in the summer. Next they found out how they could harvest rainwater. The PNLIT did a survey of the area as the topography had changed completely and the earlier sources of water had all gone. They found out that the gradient of the Brigade Millenium Avenue Road abutting the lake was just enough to let in surface runoff and pushed the BBMP to build a diversion channel to bring this water into the lake. Usha explained that after that year’s rains, 50 per cent of the lake was filled by the water that flowed down the diversion channel. They got a grill fixed to the mouth of the outlets to prevent garbage from flowing into the lake. 

The next year however, it did not rain and no water came into the lake. So the trust realised they had to look for alternate sources of water to keep the lake alive. Usha happens to live in South City, a large residential apartment overlooking the lake and she knew that the STP (Sewage Treatment Plant) was very well maintained. They were treating eight lakh litres and using only half. The other half was being let out into the storm water drain. They approached the building and requested them to let this water into the lake. Since the apartment tests their water every month, they could rely on the quality. Finally, after convincing the BBMP, who were ironically worried about sewage entering the lake, the trust signed an MoU with the BBMP, for the trust to take over the maintenance.

Floating islands

To further purify the treated water from the STP, the trust adopted the principle of hydroponics and were the first to do so in Bengaluru. They experimented with PVC platforms and then launched their prototypes of floating islands, which has proven to be a low cost, low tech but highly effective solution. 

Three species of nutrient-absorbing plants have been planted on the islands – Vetiver, Canna and Colocasia. They grow by absorbing the pollutants in the water consequently reducing the Biochemical Oxygen Demand (BOD), which is the amount of dissolved oxygen required by aerobic organisms to break down organic material, while increasing the dissolved oxygen.

The wetland near the mouth of the treated water inlet has a line of floating islands formed as a barrier, inside which there is a higher density of these plants, all acting as bio-filters for the treated water. Along the edges of the lake are strips of Aligator weed that act as buffers, the growth of which is controlled.

The PNIT has also planted over 350 trees of species comprising Mahagony, Cadamba, Singapore Cherry, Laburnum and shrubs such as Hibiscus and Ashoka Bougainvillea were also planted. At some point when the saplings were young and there was barely any rain, they bought water in tankers to keep them alive. They were counting each drop they gave to each plant. Soon they came up with the idea of a low-tech drip irrigation system. The trust asked the children in the neighbourhood to come to the lake with plastic water bottles. The base of each bottle was cut, and a very small hole was made in the lid. These bottles were then tied to each tree. The regular walkers started bringing a bottle of water for one particular tree. It was highly effective, with the advantage that only the trees received the water and not the weeds.

The lake and its surroundings have now become a thriving ecosystem. It is teaming with fish such as guppies and the Nile Tilapia. One hundred and three species of birds have been spotted so far which can be broadly classified as residents, local migrants and seasonal migrants. Species of Cormorants,Drongos, Kingfisher, Sunbirds, Woodpeckers and many more have been sighted by keen bird watchers. Agamas, butterflies, dragonflies, snakes and toads are also found around the lake.

There is at least one cultural event a month, to spread awareness about lake conservation. Many other resident associations are trying to revive lakes in their neighbourhood and ask PNLIT – that has won awards and been felicitated for their work – for advice from time to time.

(Sources: http://www.vwgzoetermeer.nl http://www.puttenahallilake.in • http://www.afcd.gov.hk http://www.scmp.com)