How towns and cities cause extinction of local plants

London, October 9 (ANI): An international team of botanists has revealed how towns and cities cause the extinction of local plants.

According to a report by BBC News, the team has compared extinction rates of plants within 22 cities around the world.

Both Singapore and New York City in the US now contain less than one-tenth of their original vegetation, reveals the analysis by the botanists.

However, San Diego, US and Durban, South Africa still retain over two-thirds of their original flora.

Both the pace of urban change and how many plants remain in a city are good predictors of whether plant species will survive there in the future, according to the report.

"The rapid and ongoing growth of cities and towns significantly threatens global biodiversity," said Dr Amy Hahs, a scientist working at the Australian Research Centre for Urban Ecology at the Royal Botanic Gardens in Melbourne, Australia.

So, Hahs and colleagues from universities in Australia, New Zealand, Singapore, the UK and US came together to try to understand how this process occurs, in order to find ways to prevent it from happening.

For the first time, the team compiled raw data on plant extinctions within 22 urban areas, organised into three categories.

First, they examined cities in which the native flora started to be transformed more than 400 years ago.

Almost all are European cities, including Glasgow in the UK, Vienna in Austria, and Zurich in Switzerland.

They also categorised cities in which the native flora started to be transformed after 1600AD, but before any floral surveys could be completed.

Such cities include New York City and Chicago in the US and Auckland, New Zealand and Singapore.

The third category included cities that had large areas of native flora at the time they were surveyed, but subsequently were transformed by urban development.

Los Angeles and San Diego in the US, Melbourne and Adelaide in Australia and Capetown and Durban in South Africa were included here.

By doing this, the researchers were able to unpick how the history of a town or city influenced how many plants became extinct as a consequence.

Cities belonging to the first two categories had by far the highest extinction rates.

However, in general, cities with more than 30 percent vegetation cover had much lower extinction rates.

The analysis also revealed that more recently built cities can expect to lose a significant proportion of their native plants over the coming decades.

"If we want to keep plant diversity in our cities, we need to protect and restore areas of native vegetation," said Dr Hahs. (ANI)