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Wednesday, June 10, 2020 By the A.M. Costa Rica staff and wire services Parakeets in the parks, wild plants thriving on asphalt, industrial buildings invaded by bats or birds of prey, recent studies show the astonishing ability of certain species to acclimate to the noisy and densely populated environment of a city, said the United Nations Educational, Scientific and Cultural Organization, UNESCO Cities, where two out of three people will be living by 2050, according to United Nations figures, are growing steadily at the expense of natural areas, forests and farm-land. The destruction of natural habitats, soil, water pollution, and the use of pesticides are all factors that disturb, or even destroy, ecosystems and the species they shelter. According to projections by researchers at the University of Pennsylvania in the United States, 90% of natural reserves that host endemic species could disappear in the coming years as a result of urban sprawl. The fact that cities harbor wild species is not surprising when as many as 423 cities worldwide, with more than 300,000 inhabitants, have developed within environments rich in biodiversity, according to a study conducted by researchers at Yale University in New Haven, Conn. Jakarta in Indonesia, for example, is expected to gain three million inhabitants by 2030, located in the heart of Sundaland, a region with some of the richest biodiversity on the planet. According to UNESCO, the threat to biodiversity caused by urban growth is therefore very real. Yet, nature does not always surrender in the face of advancing concrete. The reduced presence of pesticides, the absence of poaching, the diversity of habitats, milder winters, and the availability of water and food throughout the year favor the establishment of animals and plants in search of new spaces. But not all species are suited for city life. Only those with the genetic disposition to adapt, animal species with rapid reproductive cycles or a varied diet, have a chance. “There is a natural dynamic of plant and animal species to take over this new environment by adaptation, either by changing its habits or by evolving genetically,” said Pierre-Olivier Cheptou, an ecologist at the French National Centre for Scientific Research, CNRS. The Crepis sancta, a weed that grows around trees and along sidewalks in Mediterranean cities, has made major efforts to adapt to an environment that was not its own. Within a few generations, this weed belonging to the Asteraceae family has changed its breeding strategy – by giving priority to the production of heavy seeds that would allow it to reproduce at short distances, rather than light seeds that would not be able to germinate on concrete. The animal world also displays ingenuity in conquering environments that should be hostile to it. Some birds are able to change their habits, and even their morphology, in order to adapt. Among coal tits, they are the most alert and aggressive individuals that colonize cities. These birds lay their eggs earlier and have smaller chicks because access to food is easier. Another difference is that the more active and stressed urban tits sing louder to be heard above the urban noise, said UNESCO in its report. Ecologist Ana Catarina Miranda compared the behavioural differences between urban and rural blackbirds in a study. It concluded that the urban birds reacted more cautiously towards new objects, and were less inclined to approach even places familiar to them, compared to their forest counterparts. In order to develop, urban biodiversity will require special attention from decision makers. “Urban planning will have to change completely,” said Philippe Clergeau, an ecologist at the National Museum of Natural History in Paris. “It’s no longer a question of planting rows of a single species of tree, or artificial landscaping. We need to recreate genuine ecosystems similar to those of fields and forests.” Bramble bushes, fruit trees and wild grasses will then have to take over the sidewalks. A real continuity of plant life between the countryside and the city will have to be created, with actual “corridors” of nature. The façades of buildings and roofs will also have to be covered with vegetation. According to UNESCO, ecologists see the emergence of two urban planning models – land sparing and land sharing. The first model involves creating a solid boundary between densely populated residential areas and vast natural spaces. The Sanjay Gandhi National Park – with 104 square kilometres of forest and lakes, teeming with biodiversity – is located in the suburb of Borivali, barely 40 kilometres from the heart of Mumbai, India’s largest megapolis, and its 20 million inhabitants. The 20 or so leopards that live there tend to prey on the domestic dogs living at the park’s edge. Attacks on humans have also been known to occur, but protective measures, like limiting the number of large felines, now allow for cautious cohabitation. Land sharing, on the other hand, involves diluting nature within the urban environment by introducing a succession of grassy passages, small gardens and neighborhood green spaces. In a 2016 study , the World Health Organization, WHO, showed that green spaces in cities contribute to psychological well-being, reduced stress and increased physical activity. However, urban ecology still has many unanswered questions about the ability of species to adapt, particularly with the effects of global warming. It should not overshadow a major challenge in the years to come – that of preserving the biodiversity of natural environments. ------------------------ How can the government improve cities to further protect nature species? We would like to know your thoughts on this story. Send your comments to news@amcostarica.com |
