Yellow Dunes, Baglan Bay
In classic descriptions of coastal sand dune ecosystems, the first significant ridges of dunes are called yellow dunes. They are dominated by Marram Grass (Ammophila arenaria) but are characterised by large areas of open, mobile, unstable sand. This is the quintessential sand dune habitat where a number of iconic, sand dune species are found; species more or less confined to this habitat and not found anywhere else. Good examples in our area are Sea Holly (Eryngium maritimum), Sea Bindweed (Calystegia sepium), Sea Spurge (Euphorbia paralias) and Sea Stock (Matthiola sinuata).
While we concern ourselves with saving things like Fen Orchids (Liparis loeselii), a species with a notorious habit of undergoing wild and natural fluctuations in population size (like many other orchids), we may be taking our eye off the ball.
I was with a field course class of Biology students yesterday on Oxwich Dunes, along with Nick Edwards, Ian Tew, Penny Neyland, Laura Roberts and Wendy Harris. Nick talked to the students about how Oxwich has changed in the last 60 years. It's mostly a story of gains and losses. There has been a significant gain in stable grassland, complete with a diverse and beautiful flora, but this has been accompanied by a significant loss in open, mobile sand dune habitat. I was amazed particularly by the lack of yellow dunes where, in a thorough search, we counted only 2 Sea Holly, 1 Sea Stock, no Sea Bindweed and no Sea Spurge. Similar losses of yellow dune habitats and their associated species have been noted elsewhere, e.g. Nicholaston Dunes, Kenfig Dunes.
Fortunately, Swansea Bay still has actively accreting sand dune systems, so places like Crymlyn Burrows and Baglan Bay still support significant areas of yellow dunes. Yet, even these have been eroded greatly and reshaped by winter storms in recent years (particularly last winter). Nevertheless, these places are now very important refuges for our 'real' sand dune flora. Unfortunately they are the most threatened and least protected of all our local coastal ecosystems.
Is this a significant issue? Perhaps I can answer that with a quote from an article on Sea Holly (by Malke Isermann and Paul Rooney) which has been published in one of the recent issues of The Journal of Ecology. What they say may surprise you:
'In many coastal regions, in both temperate and Mediterranean parts of Europe, Eryngium maritimum (Sea Holly)...... is one of the rarest and most threatened plant species, mainly because of habitat loss and land-use change.'
In many European countries where it used to be a characteristic species of coastal dunes, Sea Holly is now a Red Data Book species. But, unlike Fen Orchid, it is not included in the EU Habitats and Species Directive. How long before Sea Bindweed, Sea Spurge and Sea Stock join it in the endangered species club?
While climate change and alternative (green?) energy projects put pressure on our coastal ecosystems, we need to at least preserve as best we can places like Crymlyn Burrows and Baglan Bay. Perhaps we can look forward to a time when large areas of yellow dunes will be a common site on all our beaches again. But, unless we can conserve those sites that are important refuges for yellow dune species now, there will be nothing left to colonise them. You don't know what you've got 'til it's gone!