Next week, from 7-9 February, we will have a digger on the nature reserve, using a flail to cut back some of the scrub. This blog explains what we’re doing, and why.
Nature reserves should be amazing places for nature. But they don’t just ‘happen’.
We use our ecological knowledge and experience to manage the habitats for the species typical of that site, or for the very specific needs of plants or animals that would otherwise disappear. If we took a hands-off approach, the terrestrial (dry) habitats at Conwy nature reserve would become scrubby, and eventually a woodland would develop. This would be good for woodland species, but not for wetland and grassland species for which Conwy was created.*
We manage the marginal wetland habitats annually, cutting back the vegetation on the islands to keep them open for waders and waterbirds, and cutting patches within the reedbed to encourage new growth and different densities of reeds.
The rest of the nature reserve started as grassland. Actually, it started as bare soil, but within a couple of years had become grassland. Over the last 25 years, a variety of plants have become established, and these provide food and cover for a wide variety of birds, bees, moths, butterflies and all manner of other beasties. We host a small number of Carneddau mountain ponies here, who do a great job of grazing the grassland and stomping around in the scrub and reeds.
More bramble, but less sunshine
We reviewed our management in 2016 and this highlighted the value of the reserve for its invertebrates, especially moths that like a mosaic of grass and scrub. We used aerial photographs to look at how the ratio of grass and scrub were changing, and appreciated that we were losing the open, sunny habitats to encroaching bramble.
Bramble is a great pioneer species, and provides nectar and pollen for insects that themselves become food for birds, who also love the berries. (And picking blackberries and making a crumble should be a rite of passage for every child). But in the limited space at Conwy nature reserve, you can have too much of a good thing: the space for wild flowers and insects that like warm, bare ground or open grassland is being reduced.
Good for ghosts
One example of a species that suffers from less open habitat is the ghost moth. They get their English name because the white males 'hover' in small groups over grassy areas at dusk on warm evenings in summer. County moth recorder Julian Thompson knows our reserve well, and he highlighted to us the need for more open grass for ghost moths. Our volunteer moth-recorder, Bob Evans, proved that ghost moths were still present last summer, when he found several females as well as ‘lekking’ males (in Bob's photo above, the female is in the foreground and the male is behind).
Time to go big
Our ponies help to keep the habitats open, and we cut small areas with handtools, but this month we’re adopting a more radical approach. Most of our scrub is of similar age and so we will be using a flail, mounted on the arm of a digger, to selectively reduce some of it. In some places, such as along the seawall, we will be removing quite a lot, and it will look different for a few years. We will also cut down some of the trees, as the earth bank also stops the lagoons from emptying into the estuary and we have to (by law) avoid the root systems undermining the bank.
The cut bramble will, of course, regrow, and in a few years we will cut in the places that we have left this year. We will also scrape off the surface in a few places, to create bare earth patches that insects such as digger wasps can use to nest.
In other places, such as along the Ganol Trail and behind Carneddau Hide, we will use the machinery to make a mosaic, a patchwork of scrub and grass. This will allow the ponies to access the scrub, and their grazing should create even more diverse habitat and micro-climate in sheltered patches within the scrub.
What will it mean for wildlife?
Over time, our scrub will have more diverse structure and we should retain a diverse mix of species on the reserve. Our volunteers monitor bumblebees and butterflies through a weekly transect from April to September, and along with night-time moth-recording, we should be able to track changes to the insects. In the short-term, there will be less habitat for some nesting birds such as dunnocks and whitethroats, but if we do nothing, the scrub will become old and leggy over the next few years and would become unsuitable for these birds to nest anyway.
It’s going to look messy
We can’t hide the fact that cutting scrub looks like you’ve wreaked devastation on the habitat – and because we make all areas of the reserve open to visitors, it’ll be evident for a few months, until this summer’s growth takes over. We are doing the work in February because the natural food supplies on the bramble are all but exhausted and, while some insect larvae will inevitably be affected by the cutting, the selective nature of our plan means that there will be plenty that survives. Across the reserve, we plan to cut back about 20% of the scrub.
The digger will be working along the trails in some places. This is unavoidable and the recent wet weather means that the paths are already muddy. Using a digger, rather than a tractor, means we only need to pass each point once, and hope that will minimise the impact on the trails. There will be temporary closures of some trails during the work. The reserve will remain open to visitors and we will ask visitors to follow instructions and diversions during the work.
*Footnote: nature reserve management is, of course, not the only way to ‘do’ conservation, and there is much debate about “rewilding”. There is no doubt that saving nature will require greater ambition about the scale of management (basically, bigger is better). However, Conwy is less than 50 hectares in area, so we’re tiny, and we have elected to adopt a more intensive approach to our management here.