04 December 2011

Invasive Cotoneasters at Fox Hole, Southgate

Wall Cotoneaster (reddish patches) and Entire-leaved Cotoneaster (green patches) smothering limestone grassland at West Cliff
Sections of the slopes below Fox Hole at Southgate have swathes of non-native Cotoneasters clothing the rockier parts of the cliffs. These are primarily Wall Cotoneaster (Cotoneaster horizontalis) and Entire-leaved Cotoneaster (C. integrifolius), with a few plants of Late Cotoneaster (C. lacteus) and Himalayan Cotoneaster (C. simonsii). The low growing species are particularly well suited to the south Gower limestone cliffs and are clearly reducing available niches for native wildlife.
Wall Cotoneaster (left) and Entire-leaved Cotoneaster (right).
Compare pointed vs shiny blunt leaves and small-shiny vs large-dull berries of the two species 
One obvious example of competition for space is on exposed cliff habitat where native prostrate form of Juniper (Juniperus communis) grows, this being a very scarce plant, thinly distributed along the South Gower coast. Several young plants appear to be in the process of having their space being taken over by plants of Wall Cotoneaster. The availability of suitable germination sites is also likely to reduce over time adding pressure on this vulnerable species.
Wall Cotoneaster spreading through Juniper
What can be done? The cost of clearing these invasive plants is likely to be prohibitive, especially in today’s economic climate. You can also question how effective such action would be in the long-term as recolonisation is likely to rapid given the abundance of plants in other part of Gower. So it looks like we might just have to accept this is a very successful group of alien species which look set to stay. Trying to look on the positive side at least the birds and the bees will have a feast, although this will be meagre compensation for what could be lost!
Largely unaffected cliff grassland at West Cliff, just west of Fox Hole. A Juniper bush (brightest green) can be seen in the foreground with darker patches of Wall Cotoneaster bottom right. It could be that the spread onto this more exposed aspect is constrained by climatic conditions, or that it is only starting to spread around the corner remains to be seen!


Charles Hipkin said...

This is of great concern. I think the Cotoneaster problem on south Gower cliffs is a very significant one. Your photo of Wall Cotoneaster invading Juniper habitat says it all. The local issues with Japanese Knotweed and Himalayan Balsam pale to insignifance compared to the damage to habitats and species that invasive Cotoneasters are capable of inflicting along these cliffs.

Barry Stewart said...

I know the City and Count of Swansea Biodiversity Unit did some excellent work a few years back on Mumbles Hill, trying to rid part of the site of Cotoneaster and Holm Oak. This proved to be successful at the time, but it has clearly bounced back and continues to spread and thicken up!

Anonymous said...

I've never understood why the RSPB has always promoted cotoneaster species for wild life gardens when it has been known that birds distribute it, with plants springing up around our limestone cliffs and strangling native flora for years. Mumbles Hill is swamped. It has now been added to Schedule 9 of the Wildlife and Countryside Act as an evasive non- native. Johnny Woon.