Urban Decay

(Disclaimer: This post has nothing to do with the make-up brand you see on the shelves of Sephora.)

We have been talking about urbanisation and its impacts on biodiversity the entire semester, but there is one area of urbanisation that we didn’t get the opportunity to talk about – urban decay.

What is Urban Decay?
Urban decay is when parts of a city are neglected and become so run-down it is undesirable to live in. Such areas may bring economic and social problems to the country. While urban decay is not a common phenomenon, it can happen when a city grows and develops too fast without proper urban planning. Images of derelict buildings, poor housing and sanitation come to mind when we think about a decaying area. In the case of Bangkok, Thailand, excessive urban sprawl with degrading quality of life were indicators of potential deterioration in parts of its city.

Predicted Impacts on Urban Biodiversity
What does urban decay mean for biodiversity then? While there has been little literature that covers the impacts of urban decay/ decline on flora and fauna species, I would like to make several predictions on this matter:

  1. Urban exploiters may persist, but not for long.
    Species that adapt well to the urban environment/ find urban habitats similar to their natural habitat (e.g. buildings akin to cliffs and mountains), may still be able to survive in the resource-limited, far-from-pristine habitat conditions on its decline. However, if abandoned areas of a city are left to decay without renewal efforts, its resources (food, water) are bound to run out and even urban exploiters will have to seek alternatives or face decimation. Poor sanitation in these areas may also result in polluted waters and even the most resilient arthropods may face disease and even epidemic.
  2. Species that persist may evolve alien features.
    If conditions are so bad that phenotypic plasticity (variation in appearance or function across environmental conditions) gives a species an advantage in the survival of the fittest, some exploiters may develop alien features to better exploit the environment. Corals in extreme pHs and under wave-induced stress have been shown to have differing/ extreme phenotypes (appearances/ functions), this might be a possible outcome for urban fauna if left in an urban derelict for extended periods of time (years).

Urban Renewal
Many countries have attempted to revive their decayed urban areas. In Bangkok, Calagary and Taipei, efforts had been put in to renew some of the areas in the cities that were on the decline. While it is unclear how countries decide on the decayed areas they choose to renew, it is safe to assume that the potential economic, social, and ecological value these decayed areas may have if renewed is key in the decision-making process.

The case of urban decay shows the importance of careful urban planning with the aim of building a sustainable city. Haphazard urban development may cause native species to die out, and may just cost the nation more to renew.

Chan, E. & Lee, G.K.L. (2008). Critical factors for improving social sustainability of urban renewal projects. Soc Indic Res, 85, 243-256.

Chang CO., Peng CW. (2018) Urban Renewal and Affordable Housing in Taiwan. In: Altmann E., Gabriel M. (eds) Multi-Owned Property in the Asia-Pacific Region. Palgrave Macmillan, London

Fulton, C. J., Binning, S. A., Wainwright, P. C., & Bellwood, D. R. (2013). Wave-induced abiotic stress shapes phenotypic diversity in a coral reef fish across a geographical cline. Coral reefs32(3), 685-689.

Kulsrisombat N. (2008). De Facto Urban Regeneration: A Case Study of Chiang Mai City, Thailand. In: Kidokoro T., Harata N., Subanu L.P., Jessen J., Motte A., Seltzer E.P. (eds) Sustainable City Regions:. cSUR-UT Series: Library for Sustainable Urban Regeneration, Vol 7. Springer, Tokyo

Putnam, H. M., Davidson, J. M., & Gates, R. D. (2016). Ocean acidification influences host DNA methylation and phenotypic plasticity in environmentally susceptible corals. Evolutionary Applications9(9), 1165-1178.

Tallon, A. (2013). Urban Regeneration in the UK. Routledge.