Only half the number of plant species that could blossom along the walls of the River Thames finds a suitable place to grow, yet this could potentially double with the introduction of 'green wall' technology, according to a presentation at the Royal Geographical Society (with IBG)'s international conference.
Research conducted by Simon Hoggart and Rob Francis from the Department of Geography at King's College London found that the river holds a much broader range of seeds in its water and sediment than can be found growing along its central London foreshore and embankments. Although the river walls already support almost 90 plant species, many more do not have anywhere to grow because the walls do not provide a suitable habitat.
"As any gardener knows, plants are adept at growing in unlikely places -- between train tracks, shooting up through cracks in tarmac -- but when it comes to the sheer concrete or sheet metal of city river walls, they really struggle to get a root-hold," Simon begins.
Simon is due to begin work with Thames21 trialling cost-effective new technology that has the bonus of not requiring major building works. "We're going to be testing 'green wall' technology which involves attaching specially-designed frames to the river walls. It has previously only been used on dry land to encourage plant growth, but we think it has the potential to double this aspect of the Thames's biodiversity," Simon explains.
Simon's research findings have helped secure funding through a partnership with Thames21 -- a waterways charity that uses volunteers in the city to clean 'waterside grot-spots' and create new habitat for wildlife.
"Although the river is one of the cleanest urban waterways in Europe, the section that runs through London has very little riverbank habitat, so the biodiversity in these areas is much lower than it should be. The embankments are designed to flush water and detritus through London and protect the city from flood," Simon explains. "We found only 53% of the seeds in the seed bank were growing on the river walls. Improving this section of river could have an extremely positive effect for the health of the river, creating a 'green corridor' that would benefit the whole river food web."
Rivers are amongst the most biodiverse landscapes and yet they are coming under increasing pressure from human development. "Demands for clean water for consumption and industry are only going to increase in coming years which is why it is important we keep a regular health check on our river systems and trial new technologies as soon as possible."
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