Winterton Dunes

A brief note- this blog is again about a field trip, and not about wildlife that can be found on campus. However, this was a field trip to Winterton Dunes, an incredible acidic dune system on the East Norfolk coast. It is home to lots of rare and unusual wildlife, for example a Little Tern colony, Natterjack toads, and Grayling butterflies, but this blog is about the exciting Cladonia lichens.

A picture of the landscape at Winterton, showing the sea in the background, and the grey dune system in the foreground.

The sand dunes at Winterton are carpeted in nationally-significant numbers of these amazing lichens. They are indicator species for grey dune habitat, which is a rare and protected habitat. These dunes are particularly interesting as they are acidic, rather than calcareous like those found on the North coast. This is more similar to the habitat types found in the Baltic region.

Embryo dunes at Winterton: embryo dunes forming around tufts of grass (L), the dune system looking inland, with the youngest dunes at the front and the mature dunes at the back (R).

Dune succession starts at the beach, where embryo dunes form. They then grow as sand builds up around an object acting as a wind break (e.g. some grass, a stone). As the dunes mature, plants colonise, making the dunes grow even larger. Eventually soil develops, and more complex plant communities develop, culminating in woodland. Cladonia lichens live in the middle section of the grey dunes, between the embryo dunes and the woodland.

A close-up photo of a Cladonia lichen, being photobombed by a Grayling caterpillar!

These lichens are quite rare, so Winterton Dunes is a nature reserve to try to protect them. However, there is risk of trampling from people and dogs, which is suspected to harm the lichens. To investigate whether paths are a risk to lichen communities, we designed an experiment to measure their distribution related to paths.

The vegetation on the grey dunes, including the lichens.

We decided to measure the percentage cover of lichens on and off paths to see if trampling was having a great impact. We placed quadrats in the centre of paths and 1.5m away from each edge at set points along paths. We defined the edge of a path as having a average sward height of >5 cm. Each sample was taken 10 paces apart (only 1 person walked this to control for different stride length). We took a total of 30 samples (1 sample = 1 centre quadrat + 2x edge quadrats) to make our experiment scientifically robust. The quadrat had 25 squares, so each square covered in lichen accounted for 4% cover, this was used to approximate average percentage cover of the measured area.

A diagram of the placement of quadrats in relation to the centre of the paths measured.

We found that the centre of paths had a significantly lower percentage cover of lichens than the edges.

Figure 1- The difference in percentage cover of lichens on the centre and the edge of paths at Winterton. The percentage cover of lichens at the edge of the paths (n = 60, μ = 56.4%) is significantly greater (t = 9.159, P < 0.01, df = 88) than the percentage cover in the centre of the paths (n = 30, μ = 2.4%). The darkest line in the box represents the mean, the edges of the box the interquartile range, and the whiskers the range.

Trampling has a significantly negative effect on lichen distribution. Therefore I would recommend that the site be managed so that lichens are less at risk. Conservation recommendations I would give include:

1. Rope off areas with particularly large cover of lichens to prevent people from walking through and disturbing them.
2. Informing the public through signs and notices about the lichens and how important they are.
3. Reducing the number of paths available to walk along (there are currently many paths that lead to the same destination), and instead prioritise a few main paths so that trampling is reduced.

If these measures are implemented, there should be continued monitoring of the lichens to ensure recovery and make sure that other factors are not negatively influencing their distribution.

Lichen identification

Two species of Cladonia lichen are present at Winterton Dunes, C. portentosa and C. arbuscula. They appear very similar on a surface level, but can be easily separated by some key identifiable features.

C. portentosa glows brightly under ultraviolet (UV) light at the base of its podetia (branching structures), fluorescing blue-white due to the presence of perlatolic acid, which is believed to increase acidity tolerance and may even have antiviral properties, with interesting implications for human medicine. It also has terminal branches that face in all directions and has a yellow-green colour due to increased exposure of its symbionts (algae that live inside it, providing it with energy from the sun).

C. arbuscula does not glow under UV light and its terminal branches all face in the same direction. It also takes on a more silvery-grey appearance than C. portentosa.

A close-up of C. arbuscula, with terminal branches all facing the same direction (to the left).

Comments

Post a Comment

Popular posts from this blog

Holly Leaf Miner

Image
This interesting patterning on the leaves of the Holly tree ( Ilex aquifolium ) is caused by the Holly Leaf Miner ( Phytomyza ilicis ), a parasitic leaf-mining fly in the Agromyzidae family. Its larvae burrow between the cuticles of Holly leaves, leaving a distinctive trail behind. The adult female fly lays eggs inside the soft, young leaves using her ovipositor in spring. A maximum of 5 eggs are laid per leaf, although no more than 2 become larvae, so as to avoid competition for food between individual larvae. The species is univolitine, meaning it only has one brood of young each year. This mining seemingly has no great negative effect on the host plant, presumably because not many larvae are in each leaf, and there is a high mortality rate in larvae. Old mines provide habitats for algae and mites, sheltered from predation by the leaf. A P. ilicis  mine that has been predated by a blue tit ( Cyanistes caeruleus ). Holly Leaf Miners are quite vulnerable to predation, largely by bl...
Read more

Wild Garlic

Image
This blog is about a recent trip to Lower Wood Ashwellthorpe, a Norfolk Wildlife Trust reserve, to look at ancient woodland indicators. One of these is Wild Garlic or Ramsons ( Allium ursinum ). Wild Garlic interspersed with English Bluebells (another ancient woodland indicator species). These beautiful white flowers coat the woodland floor during spring, and have a strong garlic scent, making them difficult to miss. Each flower has 6 bright white petals and cluster in groups of around 25 on the end of the stems, appearing like pompoms. Flowering early in the spring allows the plants to make the most of the sunlight reaching the forest floor before the canopy emerges and it is much shadier. Wild Garlic is in the same family (Alliaceae) as onions, chives, leeks, daffodils, and other garlics. It reproduces by bulb division and occasionally seeds. It provides an important nectar source for early pollinators and the bulbs are eaten by Wild Boar ( Sus scrofa ), though these are not found at...
Read more

Snowdrops

Image
Bright and cheerful, Snowdrops ( Galanthus nivalis ) bring excitement to the earliest days of spring. Whilst they are a non-native species, they act as a well-known indicator of warmer days to come when they flower in January to March. Snowdrops on campus, there was a good display this year! Growing to 15cm tall, the straight stems have drooping white flowers at the ends, leading to the name Snowdrop- drooping and white, like snow. They are found across the UK, favouring damp soils so are often found in woodlands and along riverbanks, but can also be seen in parks, gardens and meadows. They normally flower at the start of the year, but increasing numbers of sightings have been reported in December, and even some in November. Therefore they are being used to monitor climate change and its impacts on wildlife. You can report Snowdrop sightings here:  Nature's Calendar (woodlandtrust.org.uk)  . The Woodland Trust are monitoring changing climate and have a range of indicator speci...
Read more