Dune Ecosystems yngslas

Dune Succession Psammoseres : 

Dune Succession Psammoseres Case Study Yngslas Dunes, Wales

Note for IB Students: 

Note for IB Students The actual detail of the psammosere is not going to be in an examination. The main idea is that of sand dunes and in particular management and HABITAT RESTORATION once areas are degraded by human activity. What has caused the degradation What specific management has been undertaken.. You must be able to draw an annotated diagram What other examples of habitat restoration could we use in relation to coastal environments?

Moving to a Climax!: 

Moving to a Climax! Over time if everything remained constant environments would move towards having climatic climax vegetation. i.e. vegetation ideally suited to the climate of a region. To get to that stage they go through a series of stages (seres). The first to develop in an area are pioneer species who pave the way for other species in a vegetation succession. If this is the case from an area that has a totally new habitat and has not been colonised before it is called a “PRIMARY SUCCESSION.” There are other important localised factors such as rock type, relief and closeness to sea water Psammoseres : - sand dune ecosystems .

Ideal View of Sand Dune Succession: 

Ideal View of Sand Dune Succession The main point to note here is that this shows how an area of dunes changes over time. The original dune is (a) which is at the front of the beach Pioneer species colonise this area creating new conditions. Over time (a) changes its characteristics due to vegetation succession and new embryo dunes will develop in front of it.

Case study: dune succession at Yngslas, Wales: 

Case study: dune succession at Yngslas, Wales The diagram below is an idealised view of a transect. It shows the succession that happens in the area although many of the types of plant are not shown. In general the diversity of species increases as you move from the shoreline to older dunes. The colour of dunes changes with increased humus levels and more stability. http://www.bbc.co.uk/wales/mid/sites/coast/ have a walk in Yngslas

Fore Dunes (embryo dunes): 

Fore Dunes (embryo dunes) Lymus arenarius (Lyme grass) Sea Couch-grass and Lyme-grass, Elymus arenarius , are pioneer species on newly forming dunes. Adaptations include Tolerance of salt. A waxy coating on the leaves which enables them to retain water. The leaves are often rolled, which reduces the leaf surface area exposed to the atmosphere. This decreases the plant transpiration rates. These will begin to stabilize new dunes with their networks of root systems. They produce a more stable wind break, encouraging yet more sand to be deposited. However, as the amount of sand being deposited increases, these pioneer plants cannot grow quickly enough to avoid being smothered. Where the rate of sand deposition is greater than 30cm per year, they will be outcompeted by Marram Grass. Agropyron junceiforme ( Sea Couch Grass)

Cakile maritma (sea rocket): 

Cakile maritma (sea rocket) Both species below are also found in the foredunes and have xeromorphic properties that allow them to live in conditions of high salinity, low nutrient and water availability Honckenya peploides (sea sandwort)

Ammophila arenaria (Marram grass): 

Ammophila arenaria (Marram grass) These start to appear in the fore dunes but are more prevalent on yellow dunes. Very arid as above high water mark and sand very permeable. Adapted with leaves that fold to reduce surface area and which are shiny. Also very deep roots to tap water. These help to stabilise dunes. Grow rapidly as dunes increase in size. Roots stabilise the dune allowing it to grow too. Organic content is increased and as dunes grow above HTL then salt is washed out by rain.

Mobile Dunes (Yellow) : 

Mobile Dunes (Yellow) Notice the marram grass is dominant. However there are other plants. There are less gaps between plants here. Notice also effect of people.

Euphorbia paralias (sea spurge): 

Euphorbia paralias (sea spurge) colonize the hotter, drier slopes of the dunes. They have fleshy, waxy leaves with a high capacity for water storage. The leaves and stems also contain a white latex which makes them taste unpleasant to herbivores such as rabbits.

Semi – Fixed Dunes: 

Semi – Fixed Dunes More diversity Centaurium erythraea (common centuary) Decaying matter, animal droppings add more nitrogen to soil. Changes in colour and allows other plants to grow.

Carpet of the common dune moss (Tortula ruraliformes): 

Carpet of the common dune moss ( Tortula ruraliformes) As sand stops being deposited, Marram Grass will die out. Grey-green lichens and mosses such as Tortula ruraliformis , also colonize the dunes, combining with accumulating humus to give the dune sand a characteristic dirty grey colour. The lichens and mosses become dry, hard and dormant when water is in short supply, but as soon as it becomes available, they start to grow again. In high summer, the dried lichens and mosses give the dunes a very crunchy texture, which is almost like walking on crisps. Where there are large quantities of pulverized sea shells included in the dune sand, plants which thrive in lime-rich areas will become established.

Sedum acre (biting stonecrop) : 

Ononis repens (restharrow) Sedum acre (biting stonecrop) These leguminous species are nitrogen fixing and therefore improve conditions further for growth of other species.

Fixed Dunes (grey dunes): 

Fixed Dunes (grey dunes) Rosa pimpinellifolia (burnet rose) Much more humus and organic matter. Increased water retention and nutrient availability. Marram grass still common but not dominant. This is an area that is grazed by sheep and rabbits which will suppress the growth of shrubs.

Slide 16: 

Carlina vulgaris (carline thistle) Bellis perennis (common daisy)

Dune slacks : 

Dune slacks Between dunes the water table may be high and therefore waterlogged conditions occur leading to distinctive plants e.g. Dactlyorhiza purprella (northern marsh orchid)

What Next?: 

What Next? In this area under natural conditions you would expect the following to happen. After the fixed grey dunes is an area of Sand Dune Heath and then SCRUB appears. These consist of "armed shrubs", such as Bramble ( Rubus ssp.), Wild Rose ( Rosa ssp.) and Hawthorn ( Creteagus monogyna ). These are protected from grazing by their spines, and under their protection, tree seedlings become established. Often, these are Pine (Pinus spp.), which has xerophytic adaptations . They cast a shade which reduces the scrub species. Over a period of centuries, other tree species and a variety of woodland plants and animal species will become established, and eventually, a stable climax will be reached complete with its own self-maintaining soil system and microclimate.

Is there a real Climax?: 

Is there a real Climax? British sand dune systems rarely show the complete series of successional changes Grazing pressure of domestic stock and introduced species like rabbits is much greater than that of the wild herbivores of prehistoric times, and tends to suppress scrub and forest development, causing the succession to "stick" at the grassland phase. Thus, so long as the artificial grazing pressure remains, the grassland is a permanent community, a biotic plagioclimax (maintained by humans). Such grassland behind dunes used to be called "links", which in many places have become golf courses. Golf links too represent a plagioclimax, maintained by mowing. Another human influence on dune systems is trampling by tourists, which may destabilise the dunes themselves

Management Issues: 

Management Issues Link to map (multimap) Link to map (page 3)

Why does Ynslas need managing: 

Why does Ynslas need managing Dune Blowouts. This is a natural phenomenon that happens in high winds. But it can be made worse by human use of areas. As people trample the area plants die exposing unstable sand to the wind. The area has a small amount of woodland at the back of the dunes however there is too much competition between it and agriculture, tourists and caravan park. Who are the various stakeholders and what conflicts are there?

What is being done?: 

What is being done? Management is about trying to keep a balance between the natural environment and keeping the diversity of the area, while allowing people to use the dunes for leisure and recreation. Initially the main concern is HABITAT RESTORATION. After that it needs to be continually monitored Qu – could you draw these annotated diagrams and explain them in an exam?

Slide 23: 

Links Golf course and management Alternative view on dune stabilisation Vegetation succession in Sefton . Great site Coastal sand dune succession – primary succession from offwell. ~Devon. V good