Salt marsh or sand dune? What the plants can tell us about the emerging habitats at the Hoylake foreshore.
Over the past two years, I’ve completed 5 survey visits in total looking at the plant species that grow across Hoylake beach and their relative abundance. Using that very same survey data, I looked at Ellenberg values for salt. These values indicate how tolerant any given plant species is to salt, for example, a species that has a really low Ellenberg salt value of 0 is one that is entirely intolerant to salt. By comparison, species with high Ellenberg salt values at around 7 to 9 indicates that the species is highly adept to survive in brackish environments, like Spartina and Glassworts.
In early to mid-successional saltmarshes, these are highly brackish environments rich in salt, and the species that live in them indicate that by having high Ellenberg values for salt, just like Spartina (Ellenberg = 7) and Glassworts (Ellenberg value = 9). By comparison, species that live across other coastal habitats, namely sand dunes, that are not regularly inundated by the sea, tend to have very low Ellenberg values. Were Hoylake transitioning into saltmarsh from what was a previously raked beach, the Ellenberg values for salt we would anticipate seeing would be very high. However, were Hoylake transitioning into a dune system, separated from high tides, Ellenberg values would be very low and would probably decline over time.
This is exactly what we see at the moment at Hoylake. Average Ellenberg values for salt are now not only incredibly low currently (1.5), but they have declined over the past two years and look to be continuing to do so. In addition, plants like Sand Couch and Lyme-grass, sand dune pioneer species, have significantly increased in their abundance across the beach in just two years. Other sand dune specialists not ever found in any recognised saltmarsh community are also now established and widely distributed across the beach, including Marram and Sea Spurge.
Although some people may think that the Hoylake foreshore might be transitioning to saltmarsh and would not develop into a dune system, the developing vegetation is telling a very different story.
