My ecology and conservation group went on a field trip on Thursday the 25th April to Winterton-on-Sea to look at its acidic dune system.
Dune systems are some of the most threatened ecosystems in Europe and are often home to rare and threatened species, like the natterjack toad.
Most dune systems in the UK are calcareous, but acidic dunes such as the ones at Winterton, host some different plant species. Winterton’s dune systems have grey dunes, which are fixed and covered in grasses, heather, and lichen, and have a layer of humus (as dead plants have been broken down to make a more grey-coloured soil).
We started out identifying and learning about some of the plants growing on the dunes, such as spring beauty/miner’s lettuce, gorse, lyme grass, and marram grass. These grasses are important in maintaining the dune systems as their roots bind the sand together and stabilize the soil, preventing erosion and allowing other plants to establish themselves. There were also some oak and birch trees, whose growth had been affected by the windy conditions on the dunes, making them grow to a smaller size than I would expect them to grow in another environment, and leaning against the wind.
Next, we planned a project to examine if, and how, human trampling affects the distribution of lichen in the grey dunes.
Method and Results:
We decided to collect data on the lichen distribution every 10 paces and on several paths of different sizes to reduce bias. Path edges were defined as the point at which the average vegetation height was 5 cm or greater. Small paths were defined as having a width of less than 1 m, medium-sized paths were between 1 and 2 m wide, and large paths were over 2 m wide. We measured the percentage of lichen cover using a quadrat in the centre of the path, and on each side of the path at 1.5 m away from the edge.
The percentage of lichen cover was significantly lower in the centre of the paths than at 1.5 m away from the paths. This suggests that footfall is negatively associated with lichen abundance and that human trampling contributes to a reduction in the abundance of lichen on the grey dunes.
To reduce the negative impact that human trampling has on the lichen abundance and on the integrity of the dune system as a whole, it would be helpful to implement measures to prevent people from walking outside of the most used paths across the dunes and to the beach. As can be seen in the above image, there were already ropes in place to discourage people from walking across the dunes to the beach away from the main path. However, there were some paths leading past the rope, as well as many desire paths throughout the grey dune area. As well as the already-existing ropes, it may be helpful to put up an information board to inform the public of the importance of the dune ecosystem and why it is important not to disturb the plants and lichen. The roped-off areas and information will not deter everyone but could increase the number of people who will be cautious about how they interact with the dune system.
Cladonia arbuscula
One of the lichen species we found on the Winterton dunes was Cladonia arbuscula.
Cladonia arbuscula is a pale grey-green fruticose lichen that grows in heathland and acid dune systems, among well-lit vegetation. It can be distinguished from similar lichens as its podetia (stalks) have branches occurring mostly in threes and fours that are recurved and oriented in the same direction.
