An annual news letter for local people - No.4 Spring 1999

Biodiversity: action begins at home

The term 'biodiversity' got its big start in life from the Rio Earth summit in 19994, where the UK government and many others signed the Biodiversity Convention. This meant that they all undertook to protect the biodiversity of their own countries - in other words all their native wildlife and the natural habitats on which it depends. As a direct result, here in Britain action plans are being drawn up for plants and animals that are rare or declining, with a view to at least preserving them from further decline and if possible setting them on the road to recovery.

Why point this out in a newsletter about your local nature reserve ? Well the reason is that Cranham Marsh is home to wildlife that is so rare or so threatened that it has been listed for national action: animals like the water vole - Ratty from Wind in the Willows - or the great crested newt, and birds like the song thrush, once common in suburban gardens but now worryingly scarce.

Local biodiversity action plans are being drawn up for Havering also, and these include not just wildlife that is rare or threatened nationally but also species that are important in the local context, such as where the borough has an important part of Greater London or the Essex population.

There are a surprising number of these, because Havering, with its surrounding Green Belt and its Thameside marshland, holds a very important part of the local (to use the jargon) 'biodiversity resource'. For example, Havering's harvest mice, brown hares and stag beetles are very important in London terms and its barn owls and serotine bats are important in Essex.

OK, so that doesn't mean that Havering has biodiversity to match that of the Amazon rainforest or the Serengeti, but we do have wildlife that we can be proud of and that we ought to protect. As we encourage the Brazilians to save their marvellous rainforests and the Africans to protect their Elephants and rhino, let's not forget the valuable wildlife in our own backyard that also needs to be looked after.

Keeping Cranham Marsh Healthy

The best way to look after some nature reserves is just to put a fence round them and let nature take its course, but that is not the case for most, including Cranham Marsh. Without regular management its most valuable habitats would decline and its most important and scarce wildlife would begin to disappear.

This is true of the woods, which were previously managed by coppicing i.e by cutting the low-growing trees such as hazel to ground level on a regular cycle of ten years or so. Essex Wildlife Trust volunteers have been coppicing for the past six years, creating the mosaic of deep shade, dense underwood and sunny clearings that you can see today.

It is also true of the sedge beds and the grassland which, unless cut or grazed regularly, would soon be invaded by scrub and coarse plants which would crowd out the orchids and other rarities.

But the biggest single problem Cranham Marsh faces is water supply. Improved drainage of surrounding fields, gravel extraction and the construction of the M25 have all reduced the flow of water into the reserve, and the drier weather that global warming has brought isn't helping either.

To make the best of the water that is available we have built clay dams at intervals along the main stream. These too need to be maintained because the water voles (bless their little hearts !) dig their burrows through them and cause massive leaks. Dams also increase the silting of the stream bed which has to be cleared from time to time.

Most of the management work is carried out by work parties of volunteers who meet on the last Sunday and second Thursday of every month from August through to March and occasionally in the summer, from 10am to about 4pm (within those limits people come and go when it suits them).

More hands will be very welcome and if you would like further information, please contact the warden on 01708-220897. Training and tools are provided as required and you do not have to be experienced or super-fit.

Keep your garden healthy with Cranham Marsh compost

Cranham Marsh compost is 100% organic, made from cuttings taken from the reserve and thoroughly composted. It makes terrific soil conditioner or water-saving mulch and helps your plants and vegetables to stay healthy. Five 40-litre bags for a donation of £10 or 11 for £20, collected from the reserve, all proceeds to Essex Wildlife Trust. Ring Tony Gunton on 01708-220897 to agree a collection time.