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Renaturalizing Cities to Help Restore Urban Biodiversity

Nambul River. Source: Friends of Loktak Pat FB

In Manipur, the Government has proposal to regain the original status of Lamphelpat, an urban wetland in the Imphal City area, and the Nambul River which flows through the heart of the city. Both the wetland and the river are in high condition of wastage, degradation and pollution induced by anthropogenic activities specifically in the city area.

By Salam Rajesh


The continued discussions on climate change and its ever emerging portfolio of impacts on all forms of life on Earth, and on the planet itself, is giving thoughts to innovative ideas and re-thinking on the old ways of how to minimize the impacts through nature-based solutions.

It is with these persisting thoughts that the deliberation on renaturalizing cities through a prolonged campaign on urban biodiversity restoration now seeks to make cities compatible with lost nature in regaining part of humanity in the larger perspective of the deliberation.

Urban biodiversity is basically considered as the variability or the diversity of living organisms within a specific location, as in this case the limits of an urban city and its immediate environs.

Urban biodiversity is then the whole set of living beings and their relationships within this limited space of the cityscape. By a broad definition this biodiversity includes ecological diversity, taking structural and functional diversity into account; biological diversity, which counts the number of organisms and their relative abundance; and genetic diversity, which accounts for the diversity of genomes in each species.

What is then so specific about urban biodiversity? In a general description of its ecosystem services, urban biodiversity helps much in absorbing and dispersing unregulated and excessive urban city noise, such as those emitted from the high volume of vehicular traffic, human population, and the many other activities related to humans.

With particular focus on the importance of vegetation including tree cover within the cityscape, urban biodiversity is estimated to help disperse and absorb around 50 percent of urban traffic noise, which is why much emphasis is given on designing cities with eco-parks, green spaces, avenues lined with flowering trees, and now green buildings and ‘sponge’ cities.

Urban biodiversity is also considered important from the perspective of its function in mitigating the heat island effect, otherwise also termed as ‘urban heat dome’ effect. Vegetation and water bodies within a cityscape are known to help reduce urban temperature, which is very important in a climate change mitigation and adaptation scenario.

It is being explained simply that the process occurs through two mechanisms, such as, the plant and tree shades prevent the sun’s radiance from reaching the ground or buildings, and evapo-transpiration which is a property of the vegetation through which water is emitted into the atmosphere. The combination of the two processes is said to help in reducing the heat island effect.

What is being connected to this beneficial aspect of urban biodiversity is that the process helps reduce the need for artificial air conditioning and, therefore, saves on energy. It also breaks down the intensity of heat waves and stabilizes the micro-climate for other species that thrive in the urban biodiversity, such as birds, insects, amphibians, and reptiles.

Which is why again the concept of renaturalizing urban biodiversity is important for providing ecological corridors for the animal life that may migrate locally from a place to another in search of food, shelter or their prey base.

Urban biodiversity is again considered important for its role in absorbing air pollutants that is quite pronounced in city life. Due to the density of human and vehicular population, cities tend to concentrate air pollutants even when very few air pollutants are generated per inhabitant in their environment. The role of vegetation in trapping carbon dioxide from the air is well known, as much as they filter heavy metals and suspended particles present in the air.

Renaturalization of cities is again closely connected to the efforts on the renaturalization of rivers, in particular those rivers that flow through cities and which are in certain condition of degradation through waste disposals, pollution, siltation and eutrophication.

Across the world, many cities are giving space back to water bodies like rivers, streams, and urban wetlands. The Seine (Paris), Cheonggyecheon (Seoul), the Manzanares (Madrid), the Willamette (Portland), and the Batán (Victoria) are few examples of renaturalization of rivers across the several continents.

In Manipur, the Government has proposal to regain the original status of Lamphelpat, an urban wetland in the Imphal City area, and the Nambul River which flows through the heart of the city. Both the wetland and the river are in high condition of wastage, degradation and pollution induced by anthropogenic activities specifically in the city area.

The renaturalization of both Lamphelpat wetland and Nambul River is considered of high value for the Imphal cityscape as these water bodies play significant role in micro-climate moderation and in regulating floods, while also providing recreation and livelihoods for the local people who largely depend on these water bodies for many functions.

The only problem is in the absence of scientific discussions and specific State policy on how to carry on the process for renaturalization of such important water bodies. The conventional method of engineering had earlier failed in achieving success towards the rejuvenation of both water bodies, rather isolating the local people of benefits from the ecosystem services of the water bodies.

A remarkable feature of Manipur during periods of monarchy as in medieval period of history is the roadside plantation of banyan trees, designed to provide shade and green cover. The thought process behind this appreciative activity reflects closely to the present context of renaturalization of urban landscape.

Banyans are understood to be one of the best trees that absorbs large percentage of carbon dioxide and releases oxygen, while providing shelter and habitat for a wide variety of insect and animal life. In earlier days, aged banyans were home to sparrows, crows, bulbuls, vultures, woodpeckers, parrots, squirrels, garden lizard, ants, and a wide variety of insects. In short, banyans were vital to urban biodiversity.

The tragedy is that in modern day street designing with the need for road and highway expansion, little space has been provided for green spaces. In fact, the beneficial banyans have been chopped down left and right, without the least thought on their immense value to urban biodiversity. It could take well up to fifty years to have a well expanded banyan tree providing life to urban biodiversity.

It, therefore, simply put, is time now for the State planners to re-think on how best to work out a feasible plan to re-design the Imphal cityscape in line with the global push for renaturalizing urban landscape to address many issues of which climate change mitigation and adaption stands at the forefront of global concerns.

(The writer is a media professional working on environmental issues. He can be reached at [email protected])

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