Thames Landscape Strategy - Hampton to Kew -

Riparian habitats

There are so many different ways to see the River Thames. One such way is the new ‘London’s Arcadia’ Kraft Picnic Walk which is aimed at encouraging families to enjoy the delights of the River Thames both sides of the river between Kew and Richmond Bridges. Already we have handed out many thousands of leaflets at local libraries and schools. In fact we cannot keep up with demand at the moment such is the draw of the river.

One of the factors for the walk’s recent success may be the unseasonably warm weather that we are currently experiencing. It is like summer – temperatures are in the high teens and many trees still have an appearance more akin to early September than late October. One type of tree that lost its leaves early this year however, is the horse chestnut and recent survey work for the London’s Arcadia scheme has highlighted that this is of concern to number of riverside walkers.

The main problem that is affecting the ‘conker’ tree is an infestation of a small moth called Cameraria ohridella. As our climate gets warmer the moth has been spreading northwards across Europe, reaching the UK about five years ago and is so far restricted to London and the South East of England.

The moth lays it larvae in the leaves of the horse chestnut. As these small grubs eat their way through the plant they leave brown lines that crisis cross the leaf eventually causing it to drop. Once the larvae have pupated they fly off to the next tree thus spreading the disease. The damage caused by the infestation reduces the capacity of tree to gather light and if this happens year on year it could be a problem in older and younger specimens. I have been assured that in itself the moth will not kill the tree but this yearly infestation could have long-term implications to the population particularly if the tree has other pests and diseases such as phytophthora – a destructive fungi. How different September would be to future generations of schoolchildren if there were no conkers to play with – yet another reason why we should all sit up and take notice of climate change now before it is too late.

When putting together environmental schemes such as London’s Arcadia a huge variety of different factors (and opinions) have to be accounted for such as nature conservation, views, recreational use, historic conservation and possible changes in climate. Only after all aspects of riverside life have been accounted for can a holistic plan be implemented.

Recently we have been surveying the foreshore looking for suitable places to plant reed beds. The common reed is the UK’s largest native grass and are found at the margins of waterways and ponds. Historically, the River Thames would have been lined with huge areas of reed beds but today they are confined to one or two locations – notably at the Wetlands Centre in Barnes, Ham, Kew and Barnes Ponds and Pen Ponds in Richmond Park. A staggering 40% of reed bed habitats were lost in the UK between 1945 and 1990 and today cover only 0.03% of Capital’s surface.

Reeds are important for a number of reasons, they provide an excellent habitat for all kinds of wildlife (including birds such as water rail, reed and sedge warblers and the water vole), they look good and they help to filter nutrients and remove harmful pollutants from the water.

One location that we have identified as a possible place to re-establish this important habitat is along the Warren Footpath between Cambridge Gardens and Orleans Park. The conditions along this reach are perfect with long stretches of open foreshore at low tide and willows growing on the riverbanks between the water and the Thames Path. It is anticipated that a ‘Match’ funding application will be submitted soon to enable the Heritage Lottery Fund money from the London’s Arcadia scheme to be released in order to plant reed beds on this stretch. Many factors will need to be put in place first however, and threats to the viability of the scheme such as grazing by Canada geese and nibbling by Chinese mitten crab will have to accounted for. If all goes well and the application is successful it is hoped that within several years walkers along the Thames will be able to enjoy this most special of riverside habitats and all the wonderful wildlife that goes with it.

Another riparian (simply means riverside) habitat that Arcadia hopes to create is a sand martin wall similar to the one in Barnes. Over the past 50 years the European sand martin population has crashed on two occasions as a result of drought in the birds’ African wintering grounds. We are currently looking for suitable locations for the wall which is usually best placed on islands. The wall would be designed to fit into the landscape whilst providing a suitable breeding habitat and could be built to accommodate a kingfisher nesting site as well.

The River Thames really is a special place and we hope that the works Arcadia is carrying out will provide a sustainable future we can all enjoy. Over the next couple of weeks if you are to do one thing I would recommend going on a walk between Teddington Lock and Richmond Lock as November is the time of the annual ‘draw off’. During this period the gates on Richmond Lock that are normally closed at low tide to facilitate navigation are kept open and the river is allowed to drain out naturally. This year promises to be particularly stunning as river flows are so low. The draw off takes place between the 6th and 27th of November. Throughout this period Arcadia has teamed up with the Environment Trust for Richmond and the Ham and Petersham Association who organise annual riverbed clean-ups. These involve removing the things that have been thrown into the river over the year including glass and shopping trolleys. Families are very welcome and at each event there will be a trained archaeologist and ecologist to help identify any of the more interesting things that are seen.

The first event takes place at 10.30am on the 6th November at Richmond Bridge, followed on the 19th November at 10.00am by joint volunteer events in Petersham (River Lane) and off Eel Pie Island in Twickenham. The final event is on the 20th November at 11.00am in St. Margaret’s. See you all there.

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