Restoration Twitchiness
The RSPB highlights how the careful recreation of dry acid grassland created from workings can help attract endangered birds and reverse the recent trend for reducing the number of hectares of heathland in the UK, a contraction often blamed on quarriers.
The UK’s Biodiversity Action Plan (UKBAP) states “…development activities such as mineral and rock extraction,” are a major threat to existing dry acid grassland. An assertion that appears out of the place in Suffolk.
Suffolk Council says its minerals plans are designed to make the county the greenest in the UK. And quarriers such as Allen Newport and its Cavenham Quarry sand and gravel operation is helping it achieve this.
Allen Newport has created 48hectares of restored grassland since it started working the site in the 1960s. In the latest minerals plan it wants to extend operations west and east of the site by a total of 19.8hectares, all of which will become dry acid grassland.
UKBAP calls for the attempted re-establishment of 500hectares of lowland acid grassland by 2010. One reason is that it is a priority habitat for conservation, especially for threatened birds such as the stone-curlew.
With its long yellow legs, wailing call and the huge yellow eyes it uses to catch insects in the dark, the stone-curlew is listed by the RSPB as category red. The bird was found in 23 English counties in the nineteenth century. By 1945 there were only 1,000 UK breeding pairs, a number which is now below 300.
It is restricted to two locations – on and around Salisbury Plain and in the Brecklands, which straddle the Norfolk-Suffolk border. Any meaningful recovery in numbers requires a large increase in heath and stony grassland.
Once the habitat is created it is surprising how quick curlews populate it, Allen Newport MD Richard Stevens told MQR: “We simply created the contours and put on the top soil and they just turned up. It was simple,” he said.,
Formerly an airfield, the restored area of the Cavenham site is managed by the RSPB. There can be up to 60 stone curlews at the site in the autumn where they gather in daytime roosts before starting their migration to Africa.
Jeff Kew, the RSPB’s projects development manager, says: “It is a very good example of quality restoration, which creates suitable conditions for a range of scarce breeding birds. The quarry is quite secluded and has no public access and therefore it is very good for supporting some of Breckland’s specialist wildlife.”
In the right conditions, simply allowing plants to colonise naturally can create good dry acid grassland habitat. Once it has become established, however, grazing or cutting becomes essential in order to maintain the correct mix of plants.
Grass can be mowed until it is resilient enough to support grazing animals, although cuttings should be removed to prevent nutrient levels in the soil from increasing. On some sites, growth may be so slow that cutting is unnecessary and where it is, cutting can be delayed in some years to let late-flowering species seed.
Management is also often needed to stop unwanted species from dominating the site and smothering the desired vegetation. At Cavenham, this has included gorse management and there has been some weed wiping to control thistles.
“To some extent we are constrained in what we can do. We can’t have large areas of open water because of our close proximity to airbases and the fear of bird strike. Restoring it to date has been reasonably straightforward, although fairly labour intensive in terms of moving soils around.
“The soils are very light and fairly infertile to start with and what we did in the restoration was to use some of the surplus sand and silt from the quarrying as backfill and then put the soil over the top. Really, we have allowed nature to take its course and tweaked things here and there.
Additional trials are being undertaken on various parts of the site to try and wipe out invasive plants which aren’t conducive to stone-curlew and to see if different types of ground conditions and management create better habitat.
Thanks to restoration schemes like the one at Cavenham, stone-curlew numbers are starting to grow. For a bird once so widespread this is still a small figure and the challenge now is to return them to areas where they have not been seen for more than 30 years. Quarriers are in a key position to help.
