by Pratiksha Baruah   3 July 2020

Introduction

Globally, towns and cities are rapidly growing in area and population. If current trends continue, the global urban population is estimated to be 6.3 billion with more than 60% of the projected area to be urban by 2030 as predicted by United Nations. This continuous urban area expansion is causing a direct impact on nature in terms of biodiversity loss and environmental degradation due to changing urban landscape and natural habitats. High proportion of built-ups and impervious surfaces like roads, concrete playgrounds, etc. as a result of urbanization induces a profound pressure on natural resources, especially on protected areas, natural forests, waterbodies, hills and other spaces with rich ecological values. Studies reveal that in 2005, cities occupied two percent of Earth’s surface, but the inhabitants used 75% of the planet’s natural resources.

Therefore, it is inevitable that life on earth would not be possible without nature’s services. It’s time that we all rethink about how growing cities are continuously affecting biodiversity with urban land development and increasing population.

Even though cities only account for approximately 3% of the Earth’s surface, they are often located at important ecosystem junctions or in areas of high pre-development biodiversity. Urban areas with rapid human-caused changes to local ecosystems are accepted as a major driver of biodiversity change at various spatial scales. Presently, around 35% of India’s population is urban. This situation of overpopulation along with other developmental activities for the better living, exerts ever-increasing pressure on the country’s environment. For instance, the removal of vegetation cover in the forest area and exposed surface as a result of growing constructions on the hills in the Guwahati city has led to issues like soil erosion, water logging, flash flood and dusty environment on sunny days. Statistics show that 8% of terrestrial vertebrate species have been labeled as endangered as a result of rapid urban development. Introduction of exotic species into some habitats has had devastating impacts on the native biodiversity. Exotic or non-native species to an ecosystem introduced by humans have exterminated and disperse the native species. In the biodiversity rich Western Ghats of India, vast plantations of eucalyptus and wattle were raised by converting grasslands and shola forests disturbing the original habitat of the Nilgiri Tahr that led to their frequent visits to the towns in Tamil Nadu because of the non-availability of food plants due to extensive plantations of alien species. Pollution is another major and growing threat to biodiversity, with devastating effects on freshwater and marine habitats.

Need

It is important to highlight that urban biodiversity is crucial not only for a proper functioning of ecological processes, but also for the capacity of the urban area to absorb changing ecological conditions. Urban biodiversity is the variety and variability among living organisms found in a city and the ecological systems in which they occur. Biodiversity, or biological diversity makes up life on Earth. It encompasses the 8 million or so species on the planet that ranges from plants and animals to fungi and bacteria and the ecosystems that house them. Making cities engaged with nature sustains life of city dwellers and offer ecosystem services in myriad of ways. By incorporating environmental spaces with plants and water courses, we can establish urban ecosystem services.

Both network of green spaces and aquatic ecosystems play a crucial role by providing habitats to numerous endemic, migratory and endangered species as well as provisional services to urban dwellers. Urban landscapes may consist of a diversity of terrestrial and aquatic ecosystems that harbour rich biodiversity. Terrestrial spaces may include roadside greenery, vegetation or tree canopies, meadows, green trails, grasslands, landscaped gardens and urban agricultural lands. Preserving aquatic features of high biodiversity like lakes, wetlands, bio-swales, swamps, streams, natural drainage systems, backwaters, mangroves, coral reefs and rivers within the urban landscape, play a major role towards an efficient ecological and biodiversity related performances of urban development. Public spaces and recreational areas like community gardens, urban forests and natural wildlife areas, biodiverse playgrounds, ponds, pools, hedges, flowers under tree canopy, river banks, butterfly paradises will contribute to a healthy living environment for wildlife and people, as well as to pleasant, relaxing living environments that encourage exercise and play.

Urban agriculture can play an important role as an urban biodiversity for food security, especially during economic and political crises. Auroville Urban Farming located at the city centre of Auroville, TN is a great example of how a city has built a deep harmony with nature. It addresses innovative concepts as integral landscaping, rooftop gardening, agroforestry, grey-water system recycling, participative and community building efforts. Another example is the Yamuna Biodiversity park, on the flat of alluvial plans of the river Yamuna in Delhi is a biologically rich landscape of grassland communities, a wide variety of fruit yielding species of plants, a rich repository of medicinal herbs and native locally extinct century old flora and fauna. Urban lakes are important part of urban ecosystem that perform significant environmental, social and economic functions, ranging from being a source of drinking water, recharging groundwater, acting as sponges to control flooding, supporting biodiversity and providing livelihoods. Kaikondrahalli lake in Bangalore is a unique example which was restored using a socially inclusive model that was once on the verge of extinction has been ultimately restored with clean water flowing in. Around 37 bird species, including migrant birds, have been spotted at the lake. One of the most widely cited examples of the importance of functioning ecosystems for city water supply is the New York City Watershed. This watershed is one of the most important natural resources and also the largest unfiltered water supply in the United States, providing approximately 1.3 billion gallons of clean drinking water to roughly nine million people every day.

Yamuna Biodiversity Park, Source: (Artificially Constructed Wetlands for Urban Sewage, 2020)

Biodiversity in cities also helps in regulation of ecosystem processes such as urban temperature regulation, noise reduction, air purification, run-off mitigation and pollination, pest regulation and seed dispersal and waste treatment.

Ecological infrastructure like water areas and vegetation in cities regulates local temperatures and buffers the effects of urban heat islands. Urban soil and vegetation belts have the ability to attenuate noise pollution through absorption, deviation, reflection, and refraction of sound waves. As air pollution from transportation, industry, domestic heating and solid waste incineration is a major problem for environmental quality and human health in the urban environment, promoting and protecting vegetation cover in urban systems can improve air quality by removing pollutants from the atmosphere.

With climate breakdown affecting the environment, ecological features have a capacity to adapt to its consequent challenges for cities. Healthy wetlands and other aquatic ecosystems protect communities from catastrophic flooding by absorbing floods. The aquatic ecosystems also act as natural barriers to cities from storms, heat waves, sea-level rise and play a crucial role as fresh water reservoir in drought prone areas. Vegetation cover and its underlying soil reduce surface runoff by intercepting water through the leaves and stems.

Furthermore, ecosystems like wetlands filter out and decompose organic wastes from urban effluents by storing and recycling waste through dilution, assimilation and chemical re-composition. Likewise, plant communities can play an important role in the decomposition of many labile and recalcitrant litter types. In urban streams, nutrient retention can be increased by adding coarse woody debris, constructing in-channel gravel beds, and increasing the width of vegetation buffer zones and tree cover.

Pollination and seed dispersal are important processes in the functional diversity of urban ecosystems. However, habitat loss and fragmentation due to urban development and expansion is causing threat on the pollinators such as insects (bees, wasps, moths, butterflies, flies, beetles), hummingbirds, perching birds, etc. Therefore, green spaces like community gardens, private gardens and urban grasslands are important source areas that can enhance the diverse communities of species, which in turn enhance seed dispersal.

At the same time, maintaining healthy biodiversity contributes significantly to the resilience of a city in the face of climate emergency thus managing greenhouse gas emissions. Trees in cities act as a carbon sinks by storing excess carbon as biomass during photosynthesis that can potentially slow down the accumulation of atmospheric carbon in urban areas. Biodiversity parks, theme gardens and parks are good public spaces within cities that can have massive numbers of tree covers that can help both environmentally and economically.

Cultural and economic benefits earned from an urban landscape include recreation services, thereby enhancing human health and well-being and aesthetic services, that may form an identity to the region.

Way forward

But the good news is that, better late than never, we still have a chance to reverse the trends of biodiversity loss by reimagining our relationship with nature and taking steps to increase ambition and accountability for further urban environmental protection. Local governing bodies like Municipal Corporations and State Biodiversity Boards should step ahead for preparation of City Biodiversity Index (renamed as Singapore Index on Cities’ Biodiversity, or Singapore Index) as a monitoring tool for evaluation of their progress in urban biodiversity conservation and also preparation of Natural Asset Maps showing blue-green infrastructure of the cities to strengthen integration of biodiversity management at all levels of governance and communicate the significance of ecosystems to the city dwellers.

Cities have been called one of mankind’s greatest inventions”. However, instead of being blindsided by the increasing detrimental impacts of ongoing rapid urban expansions, we should consider it as a fleeting opportunity to act in a way that safeguards the urban ecosystems critical for human and overall environmental wellbeing. Effective integration of local governments through protection of biodiversity and ecosystem services in their planning efforts can help tremendously in creating and protecting natural habitats in cities. Natural ecosystems harbour more species than disturbed or manmade landscapes, hence, there is a need to protect natural areas which includes natural water bodies, river, dense green areas, natural grasslands and open spaces, in a city for a sustainable urban biodiversity. While according to Ministry of Environment, Forest and Climate Change (MoEFCC) guidelines, a city should have 33% green cover of its total area, Pimpri Chinchwad Municipal Corporation (PCMC) has prepared its City Biodiversity Index showing an appreciable rate of 30.2% of natural areas. It is recognized that the fragmentation of natural areas affects different species differently. For example, a road may not be a barrier for birds but it can seriously fragment a population of arboreal primates. Furthermore, to encourage positive action to increase connectivity or reduce barriers to connectivity, it would be more meaningful to measure connectivity rather than fragmented plots. Hence, different patches of natural areas like agriculture, dense green areas, gardens, grasslands, open patches, river and water bodies, can be considered as connectivity measures or ecological networks to counter habitat fragmentation.

Governance and management towards the maintenance and enhancement of biodiversity by city administration is another important component to ensure the maintenance and enhancement of biodiversity in cities. Immediate focus should be given by local bodies on total city’s budget to biodiversity related administration as a representation of the city’s commitment towards environmental stewardship. The cities also need to increase the number of outreach programmes, biodiversity-related institutions like zoological park, floral recreational garden and bird boards, medicinal plants garden, etc. that will strengthen the institutional capacity and enhance biodiversity conservation in a city through public awareness and education.

Kochi Municipal Corporation prepared an urban biodiversity map as a visual interpretation of the existing urban ecosystems and key animal and plant species to communicate the richness of the city’s biodiversity to its inhabitants. The infrastructure mapped includes river, estuaries, wetlands, beaches, backwaters and ponds, cultivation lands, mangrove patches, home gardens, playgrounds, open spaces, inland fisheries, hill forests and marshlands. While drawing attention to the fact that even urban landscapes have their own biodiversity, the map is the first step towards preparing a local biodiversity strategy and action plan for Kochi. The GIS-based survey is also a need of the hour within city limits that identifies ecologically sensitive and biodiversity-rich areas along with pictorial handbooks on species of trees and labelling of trees as part of biodiversity conservation initiatives.

Kochi Urban Biodiversity Map, Source: (In a first, Kochi gets a biodiversity map, 2019)

At an individual level, we can also help integrating biodiversity in our surroundings by making permanently available resting sites for the species. We can equip special recessed nesting bricks, stacked bricks, bio-swales, gardens, green roofs and green facades to enrich the urban landscape with biodiversity and promote health and well-being through recreation. They provide an excellent surface habitat for a wide range of plants and have a lot to offer mammals, birds and insects as very substantial contribution to biodiversity. Green roofs and façade garden are a perfect solution for recovering rainwater and the planted plants are a source of food such as nectar, pollen or berries, nesting sites for birds, making a substantial contribution to biodiversity.

For a mega diverse country like India enriched with different ecosystems and presently where the Government has taken major national level initiatives towards securing environmental conservation, it is much needed to contribute towards strengthening the biodiversity conservation across our cities.