Dune Slacks at Aberffraw

Anglesey contains some of the finest examples of coastal dune ecosystems in the UK. So what is a "dune slack" I hear you scream... well don't ask me I've never heard of them.
Taken from the Joint Nature Conservation Committee..

Dune slacks are low-lying areas within dune systems that are seasonally flooded and where nutrient levels are low. They occur primarily on the larger dune systems in the UK, especially in the west and north, where the wetter climate favours their development when compared with the generally warmer and/or drier dune systems of continental Europe. The range of communities found is considerable and depends on the structure of the dune system, the successional stage of the dune slack, the chemical composition of the dune sand, and the prevailing climatic conditions.

Dune systems at aberffraw Source: geograph.org.uk

We visited the dune slacks near Aberffraw with CEH so we could get an idea of what exactly they are. The Aberffraw Dunes are Sites of Scientific Interest (SSSI) and also Special Area of Conservation (SAC) as well as being an Area of Outstanding Beauty (AONB). We were taken around the site in two groups with Jenny - a PhD student and Hilary. We then examined the dunes in a number of ways; using Differential Levelling to determine the groundwater elevation from sea level, taking soil and water samples (to be analysed at a later date) and undertaking a botanical survey using quadrats.

These techniques were used by Jenny for her 3 year thesis on the effects nitrogen were having on the dunes as well as changes to the water table that are partly attributable to the growth of commercial forest in the surrounding catchment. Dune slacks can be classified into different systems dependent on the vegetative communities found. The NVC classification is as follows (source);

• SD13  Sagina nodosa – Bryum pseudotriquetrum dune-slack community,

• SD14  Salix repens – Campylium stellatum dune-slack community,

• SD15  Salix repens – Calliergon cuspidatum dune-slack community,

• SD16  Salix repens – Holcus lanatus dune-slack community,

• SD17  Potentilla anserina – Carex nigra dune-slack community.

With Hilary's help we were able to determine the composition of the dune slack system as SD14-15. We reached this decision by using 1m2 quadrats and identifying the species within each quadrat, as well as the percentage cover of each species, giving us an overall estimation of biodiversity.

Following the biodiversity measurments we went on to calculate the water table elevation from three dipwells on-site. Using a GPS system we located each dipwell, then measured the water level height using a "dipper" that emitted a beeping sound when in contact with water as well as taking a water sample from each dipwell using a pump. To measure the elevation of each dipwell a Theodolite was used;
"a Theodolite is a precision instrument for measuring angles in the horizontal and vertical planes"
This provided us with accurate measurements for determination of water table height.

Treborth Botanic Garden & Malltraeth Marsh

Unable to attend this trip I will give a brief description of both sites and what the rest of the MSc students got up to.

Treborth Botanic Garden
The university bought the land that the site resides on in the 60s, and the gardens are now used to teach the university's students along with local schools and community groups.

Map of the Treborth site

The gardens are home to a huge variety of species which are grown indoor and outdoor, part of the woodland at the site is an SSSI. The aim of this trip was to learn about wetland plants that grow at the site that can be found in many wetland areas. Many North Wales plant species native to Snowdonia and coastal regions can be seen at the site, making for a great learning experience for anyone to enjoy. The MSc students collected plant samples from a pond which lay inan area of land that had not been plowed for 60 years, these which were then taken back to the lab to be identified using microscopes and handbooks. Below is a list of some of the species they identified..

• Common Duckweed
• Ivy Leaved Duckweed
• Greater Spearwort
• Rigid Hornwort
• Water Mint
• Water Starwort
• Spyrogira
• Juncus effusus

Malltraeth Marsh

Aerial image of the marsh (RSPB)

The students visited the marsh also known as Cors Ddyga in the afternoon after the botanical garden. The site covers 273ha of marsh, reedbeds, wetgrassland, pools and lakes and is an SSSI located in Anglesey. The RSPB have a reserve situated in the north east corner of the site as it is a notable bird breeding ground, with their main aim to provide a suitable habitat for Bitterns ensuring they return to breed at the site. Upkeep of the clay ditches maintains water levels encouraging an exclusive swamp area for the bittern to breed.

The site is grazed by welsh mountain ponies and management at the site is key to ensuring ground nesting birds return in the summer, this is achieved by reducing grazing. Nesting sites for waders are controlled by creating shallow water ditches where they can feed.
Many species of plant inhabit the area including..

• Bog Bean
• Branched bur-reed
• Club rush
• Common reed (Phragmites)
• Juncus bulbosus
• Blunt-leaved pondweed
• Grey willow
• Stonewort
• Bistort
• Field rose

Many other species inhabit the area including the moss Sphagnum immersum.

These sites both seem like amazing places to visit and I am definitely going to visit them at some point. Hopefully when the weather gets a bit nicer, but i suppose we are in Wales.....

Llyn Padrig

View of Llyn Padrig from the surrounding field

Llyn Padrig is an SSSI site on Anglesey, the wetland has formed in a former lake basin and is now a basin mire. Wetland plant communities have encroached into the lake, but there is still an area of open water present at the site. The site has no public access but luckily the university is granted special permission to visit the site, which is great news for us as we got to experience an amazing wetland. There are a range of habitats surrounding the lake including a wet woodland (with willow and birch), a floating fen and also an area which is becoming terrestrialised.

The willow scrub plants encroaching the lake

We took 3 soil samples for the site, one near the lakes edge, one from the floating fen and one the terrestrialised area. From each of the 3 sites we analysed the pH and conductivity and also collected a sample to take back the lab to test further.
Managment is required to keep the site as it is, CCW has a number of management strategies in place including grazing. Which helps keep scrub at bay, it should also be noted that the dung supplies an important food source to many invertebrates. In the past drainage of the site saw the water level drop by around 2m, which is bad considering that one of the main characteristics of a wetland is a high water table!! It is therefore important to make sure that no further drainage ditches are dug.

Wildlife
Heres a list of some of the wildlife that can be found at the site...

Typha (Cat tails at lake edge)

• Sphagnum
• Bogbean
• Cinquefoil
• Bottle Sedge
• Common Cotton Grass
• Typha (Cat tails)
• Calliergin Cuspidatum
• Greater Spearwort
• Alder
• Grey Willow
• Birch
• Water Starwort