7. Winterton

 Sand Dunes

We began our field trip here by marching straight to the beach and slowly walking back away from the sea, inland. We were taking quadrats every 10 paces away toward the dunes and beyond into the shrub and eventual tree line.

As you would expect the beach was sandy will no plants in the littoral zone, yet not far from high tide perhaps 20 paces small isolated clumps of marram grass (Ammophila arenaria) began to appear in the shifting sand, and as we moved further on those small clumps poked out of small mounds of sand which had been captured by the plant, these became numerous like isolated mole hills. and further back still they became clumped into mini dunes a meter or so across and 30cm high. Ten paces more and they were proper dunes thick with marram. 

As the dunes became taller, and other ground hugging plants began to appear - such as lichens - at the bases of the marram grass - and walking inland became more diverse with other small plants as the dunes became more stable and older. with the marram grass acting as a pioneer plant, dune creator and stabilizer of windblown sand.  

The dunes were becoming about 2-3 m high and the diversity increased the marram grass eventually gave way to heathers Calluna Vulgaris and Erica tetralix and other small shrubs, in the final quadrats trees like oak Quercus rubur became more frequent, but these oak were stunted and probably older than they looked, I suspected their DBH would indicate them to be 5- 10 years old on many of these oaks, but DBH is not a good indicator of tree age where other variables like high wind, salt spray and cold have influence on tree growth rates, much as it would be for high altitude oaks. I suspect many were probably 20-30 years old oaks.

Where dunes finished, the heather was in a matrix of lichens and ever less marram, behind the dunes the land flattened out and human footpaths were evident, winding and crossing as regular dog walking and visitors had decreed with their foot fall.

We carried out 8 transect quadrats across the paths at 90 degrees to the footpath direction.

We were trying to establish if lichen coverage – 10 m either side of the path - was influenced by the paths and for what distance. Clearly the footpaths themselves were entirely sand with no plants at all, as it would be on a footpath across a grass playing field, few plants can grow under constant footfall.

Below are our results;

The y axis is % of lichen cover and the x axis is distance 10 m from path left and right 0m being far left and 21 m being far right

x axis each coloured segment represents a percentage of lichen in a different transect.

y axis shows the percentage of lichen in a quadrat (100% max to 0% min), piled on top of each other, maximum possible coverage for all paths would be 1000 (ten quadrats of 100%) far left and far right. this gives a good indicator of lichen increasing the further left or right one moves away from sandy path in centre with 0% lichens.