How and why does the sand dune succession at Coatham Sands, North Yorkshire change?

During September 2003, year 12 visited Coatham Sand Dunes on Redcar beach in North Yorkshire. Here we were able to develop knowledge and understanding, as well as the skills necessary to be able to analyse, interpret and evaluate data which we collected whilst away. We used a variety of methods to collect such data such as profiling, quadrat’s, soil testing and microclimate, in order to use the results to answer a related question of our choice. I have decided to investigate the changes during the sand dune succession, which will include results and reasoning for pH and soil moisture, plant species diversity, soil profiles, and sand dune profiles.

Here is a map of where Coatham Sands is and what surrounded the area:

Hypothesis

I predict that the vegetation type will change across the dune system with distance from high tide – species diversity and total percentage cover increases too. As the dune succession develops inland, I feel that soil characteristics such as pH, depth, and moisture will change. I expect the soil nearer to high tide to have a more alkaline nature and have a lower moisture content, whereas soil further from the sea will be acidic, hold more moisture and the plant diversity will be greater.

The sand dune succession at Coatham sands follows the general pattern of most other sand dunes such as the sand dunes at Dawlish Warren. There are five main stages – embryo dunes, fore dunes, main ridge, grey dunes and finally the climax zone. The changes in shape and characteristics of each dunes are due to changes which I shall be explaining and using first hand data which we took to show this.

The first pioneer species to develop are lime grass, sea crouch and marram grass. This can be shown by in this kite diagram which illustrates how bare earth covers most of the first dune, and then marrram grass is the predominate plant. This is shown by the area of marram grass shaded in at between 30and 50 meters from high tide mark. When winds blow from the sea, the sand is moved up the beach by saltation. Sand is trapped by berms or sea grass, at the point of the highest spring tides. These sand deposits will build up and become colonised by plants such as marram grass which is adapted to the maritime conditions and has long roots to enable them to survive the shifting sand. The grass traps more sand and their roots hold the dune together, stabilising the area. Further fro the sea, the dunes increase in size and the vegetation become more diverse as the shelter from the wind increases and the supply of sand is less. I have drawn a sand dune profile and annotated it to show the change in the size and shape of the succession. We used ranging poles, a clinometer and measuring tape to measure the profile of the dunes. However, there are limitations such as human impact can fundamentally alter the dune transect and so this must be accounted for.

The diversity of the vegetation can be seen on the kite diagram as it shows how as one moves further inland, from zone to zone, more plants are able to grow as there is less competition and more favourable conditions such as less wind and slat from the sea. Quadrats were used to estimate the percentage vegetation cover and diversity of plant species, and we put a quadrat down every 10 meters to get accurate results. Soil Ph tests illustrate how the soil is a lot less alkaline in these dunes, where there is more humus, compared to soil at ...