When green turns grey

As cities grow, trees that call them home often give way to human progress. Urban deforestation needs an immediate, scientific remedy
Bengaluru, where trees and buildings fight for space
Bengaluru, where trees and buildings fight for space(Photo | Amol Gaitonde)

The recent pre-monsoon showers in Bengaluru resulted in close to 200 trees being uprooted across the metropolis, with over 350 branches falling off and blocking its main thoroughfares. The Bruhat Bengaluru Mahanagara Palike (BBMP) received more than 190 complaints of uprooted trees in less than two weeks.

As of 8.30 am on May 10 alone, the India Meteorological Department (IMD) recorded that Bengaluru had received 14 mm of rainfall, along with strong winds, in the last 24 hours, flooding several key parts of the city and uprooting 70 trees.

Trees falling prey to the vagaries of nature is not an unexpected phenomenon, but healthy specimens succumbing to sudden changes in weather, especially in urban areas, is a matter of concern.

Trees in a concrete jungle

Bengaluru, the Garden City, is grappling with serious issues related to dwindling tree cover today. Recent research points to unbridled concretisation and infrastructural activity for the fewer trees that we see around.

A study by the Indian Institute of Science (IISc), Bangalore, has found that over the past five decades, 93% of Bengaluru has lost its lakes and green cover to urbanisation, coupled with a 79% loss in water resources and 88% loss in forest cover, while construction soared over 1000%.

Accordingly, rapid urbanisation has a direct, detrimental impact on the health and quality of trees, potentially resulting in an environmental catastrophe in the decades to follow.

Urbanisation is an inevitable feature of human progress. As human beings grow, economically with better standards of living, along with their population, their surroundings grow in tandem, with grander living spaces and creature comforts, including vast road networks, airports, railways, and places for recreation. Rapid urbanisation reflects an enviable standard of living, but a better quality of life calls for good health and a sustainable environment. Hence, trees well-suited to the urban setting, give the much-needed succour and maintain a city’s temperature cycle and provide fresh and clean air to breathe, to say the least.

However, urban deforestation, where trees either fall prey to natural factors such as inclement weather, or are simply razed to make way for further urbanisation is a global trend, especially in developing countries. In India, for instance, the demand for land is constantly increasing to provide for various human needs. Urban spaces and localities are continuing to expand at a rapid pace.

With the burgeoning cityscapes, the vegetation cover within the cities and beyond have been retreating, threatening local biospheres, causing air and water pollution, health issues, and economic disparity. Encroachment and decay of urban water bodies have compounded the problem, as seen in the acute water crisis that Bengaluru has been noticing in recent times.

The IISc research attributes the city’s water problems to a drastic depletion of its lakes. The city’s water spread area has shrunk from 2,324 hectares in 1973, to just 696 hectares in 2023, owing to concretisation. Around 98% of the remaining lakes are encroached upon, while 90% are polluted with untreated sewage and industrial effluents, affecting groundwater recharge.

Besides, the unusually high soaring temperatures experienced in Bengaluru recently, followed by intense flooding even after moderate rainfall calls for course correction. Currently, several cities worldwide are experiencing what is called ‘urban heat island’, which occurs when cities replace natural land cover with dense concentrations of pavements, buildings, and other surfaces that absorb and retain heat. All these ill-effects have a direct correlation with the declining green cover.

Where did the trees go?

Trees are crucial to the urban ecosystem, helping to improve air quality, reduce heat, ensure regular monsoon, and enhance the overall aesthetics of cities.

However, urbanisation has a serious impact on the survival of trees, usually demanding the axing of mature trees, which changes soil composition, and alters the microclimate of the surroundings, which in turn leads to a loss of biodiversity and ecosystems.

A holistic approach is crucial to understand the complex interactions between trees, their urban environment, infrastructure, and climate. But what causes urban deforestation?

Apart from deliberate felling, the spread of urbanisation itself poses a challenge to trees. Land used to set up buildings, roads, and other infrastructure projects negatively impact the trees that call it home.

Essential nutrients for a healthy ecosystem

Nitrogen Essential for photosynthesis

Phosphorus Impacts PH levels of the soil

Potassium Essential to determine the fruit quality

Calcium Determines growth of the trees

Magnesium Core of the chlorophyll molecule

Boron Essential for the trees’ growth hormone

Copper Important for seed production

Manganese Essential for leaf health

Molybdenum Helps transfer nitrogen to useful nutrients

Zinc Essential for metabolism and enzyme function

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