Cors Dyfi is a wonderful place to visit and as people walk along the boardwalk to the 360° Observatory to view the ospreys, it is easy to see it as a stable and natural environment, whereas the reality is, that like almost all habitats in the UK, what we see today is the result of a long and continuing process of natural and man-made change.  As little as 12,000 years ago, at the end of the last ice age, most of the UK would have resembled arctic tundra and it would have taken several thousand years for the plants and animals that we are familiar with today, to colonize the land from the warmer climates of southern Europe.  One of these colonizers would have been Homo sapiens and although the first people to cross the land bridge from the continent would probably have lived a nomadic life, hunting animals and gathering food from extensive woodlands, it wasn’t long before the first farmers arrived.  From then on changes to the landscape of the UK have increasingly been influenced by human activity and at an exponential rate from the 19^th Century, as the industrialization of our society began.

Similarly, Cors Dyfi (the Dyfi bog) has seen many changes over the last few hundred years due to the influence of man, from estuarine salt marsh to reclaimed grazing and then to forestry, before returning to today’s mixture of bog, swamp, wet woodland and scrub.  The nearby area also has an industrial heritage of shipbuilding and has been the location of a busy port, so humans and wildlife have had a long history together on this site.  However, beneath the surface vegetation is a deep layer of peat that shows that prior to this time, the site was part of a more extensive area of bog. 

Mass tree planting is not just a recent focus

After the First World War the Government recognized that the UK had lost many of the forests that used to cover the country and embarked on a project to plant new ones.  The Forestry Commission was set up in 1919 to manage the forest creation both by managing the planting on state owned land, as well as providing grants and advice to people wanting to plant trees on private land.  The motivation was mainly to provide a source of timber as a raw material for construction and manufacturing, rather than to recreate the ancient woodlands and the trees used were mainly fast-growing conifers, planted in monocultural blocks for easy management and harvesting.  The rate of planting accelerated after 1945 with eventually, by 1996, close to 900,000 hectares planted on state owned land and another 500,000 hectares on private land (a total of around 5,400 square miles or 14,000 km²).  Of these, about 15% were planted in Wales which included the 13-hectare block of Sitka Spruce known as the ‘Dyfi Bryncynfil Forest’ which is now the site of the Cors Dyfi Nature Reserve.  These new forests created habitats that allowed some species that are coniferous woodland specialists to increase in numbers but the general impact was a significant loss in biodiversity.   I believe that there is an opportunity to learn from these past episodes of mass tree planting and try to make sure that the current new wave of forestation is done in a way that does not repeat the mistakes of the past.

The creation of Cors Dyfi Nature Reserve.

In the mid 90’s, the plantation was clear felled and the land passed to Montgomeryshire Wildlife Trust to manage as a nature reserve.  The wood extraction process left the site clear of trees, but badly damaged by the machinery used to cut and clear the wood from the site.  The past 25 years has been a process of managing the site to return the area to a healthy mixture of bog, swamp, wet woodland and scrub, supporting a plethora of animals and plants.

Cors Dyfi today

The wetness of the site means that access is restricted to a boardwalk through the centre of the site which leads you to the 360 Observatory.  Most visitors pass quickly along this route, as they are excited to see the ospreys, but this path also enables you to see many of the interesting habitats present on the site and makes for an interesting visit at any time of year, even when the ospreys have left for their winter home. 

Finding a plant ‘dinosaur’

One of the first unusual plants that you will encounter as you leave the new visitor centre is Royal Fern.  These impressive ancient plants have remained largely unchanged since the early Jurassic period (180 million years ago) and can grow up to 300 cm tall.  Unfortunately, they were much loved by Victorian gardeners and were collected to stock ferneries and also for their fibrous roots which were used in orchid cultivation, significantly depleting the wild plant population.  Because of their propensity to live in the middle of bogs, away from grazing animals, it is usually very difficult to get a close-up view of a wild plant but there are a good number of specimens scattered across the reserve and several close to the path.

Mesmerising Myrtle

This is a plant that survived from before the afforestation of the site and grows almost like a hedgerow alongside the first section of the boardwalk; you may not recognise it as anything unusual until you brush gently against the leaves, when you will release a strong aromatic scent.  The oils that create this aroma are used widely in many products and the plant is grown commercially in some places.  The components that make up this scent are part of the plants chemical defences against being eaten and when extracted can be used to make insect repellents as well as being used in fragrances.  Despite this there are some specialist insects, like the Rosy Marsh Moth, that are not deterred and live exclusively on this plant.  This moth is a very rare species that was thought to be extinct in the UK but was rediscovered in 1967 in a number of bogs in Wales.  Unfortunately, although this moth is present at the reserve, you are unlikely to see it as the adult is night flying (late July and August) and the larva also feeds at night (from September, through the winter, until mid-June).  I can’t leave the subject of Bog Myrtle without mentioning that, when I arrived, some of the leaves were being carefully harvested into bags before being taken to the Dyfi Distillery to be used as one of the botanicals to flavour their original Gin; so, it is possible to reimagine the experience of walking down the boardwalk while having a quiet drink at home!  

Sphagnum and the other guys in the band

As you walk further along the boardwalk, the less scrubby areas allow you to see the typical bog plant communities growing amongst the cushions of Sphagnum.  10 different species of Sphagnum moss have been recorded on the reserve and they are one of the key organisms that create the conditions for accumulation of plant material to form into peat.  As many will know, peat bogs are one of the few terrestrial environments that have the capability to continually accumulate organic matter from plants and thereby remove and lock up CO₂ from the atmosphere.  In a bog, carbon in the decaying plant material is prevented from oxidizing by the wet, acidic and anaerobic conditions under the moss.  However, if anything causes the surface to dry out, the decomposing plant material and eventually the sedimented peat, will start to oxidize and the carbon will be released back into the atmosphere as CO₂.

Other plants contribute to the process by stabilizing the top layer, as well as adding additional plant material and importantly, provide shelter for a specialized community to exist in these habitats.  Typical flowering plants include the well named Marsh St John’s-wort, Marsh Violet, Marsh Pennywort and Marsh Bedstraw.  Also present in the bog community are plants that are more widespread in damp soils such as Greater Bird’s-foot Trefoil, Lesser Spearwort, Common Valerian, Purple Loosestrife and Yellow Iris.  There are also some bog specialists such as the Round-leaved Sundew, but unfortunately these are not visible from the paths.

Pond Life

There are several areas of open water on the reserve which make good breeding sites for amphibians, as well as an excellent place for watching dragonflies and damselflies, with 18 species recorded here.  The males of some of the larger species of hawker, such as the Emperor Dragonfly can be quite territorial and will chase away intruders from the pool and don’t always limit their aggression just towards others of the same species.  During the summer, blue damselflies are always fliting amongst the rushes at the margins of the pond and are usually a mixture of Azure and Common Blue.  These two are very hard to tell apart unless you can get close up and examine the small black marks on the second abdominal segment.  The Common Blue Damselfly has a mark a bit like an ‘ace of spades’ or goblet and in the Azure it is more of a ‘U’ shape. 

Although they look delicate the adult damselflies are more than capable of catching insects as large as a cranefly however, it is the damselfly and dragonfly larvae that are the real carnivores of the pond.  In the early spring they feast on invertebrates and tadpoles, but they are capable of catching anything that moves in the pond.  They have a uniquely modified lower lip (labium) with sideways hinged spines which is folded double beneath the head and is extended rapidly forward to catch their prey.  They also have very complex larval behaviours which, within an individual species, may involve spending as little as one year before emerging as an adult or up to four years, depending on habitat and climate factors.  Also, some species enter a resting stage or diapause where development is halted in order to synchronise emergence at a particular time of year to help with mating. 

Succession from marsh to scrub

As you walk further along the boardwalk you will notice that only a small proportion of the site is made up of low growing vegetation, whereas much of the vegetation is much taller with lots of sallow, with a few birches and alders.  Open scrubby habitats are being increasingly recognized as some of the most biodiverse environments in the UK and at Cors Dyfi it is particularly important for a wide range of bird species - including unusual ones like Cetti’s and Grasshopper Warblers - as well as supporting many insects, especially moths (over 500 species have been recorded on the reserve!).  Unfortunately, this situation is dynamic and over time the woody shrubs will gradually overrun most of the open areas, leading to a transition into a wet woodland, causing the loss of many of the current species.  In order to try and manage this issue there have been a number of interventions to limit the growth of woody vegetation.  In such a wet place you can probably imagine that manual clearance is quite challenging so for a number of years, a small number of water buffalo spent the summers in different enclosures on the site and have been largely responsible for maintaining the open areas that exist today.  However, looking after these animals, especially during the winter when they cannot be left on the reserve, has proved challenging and different options have been explored. Earlier this year Montgomeryshire Wildlife Trust was licensed by Natural Resources Wales to release beavers into a large well fenced enclosure on the reserve.  Over the next few years their behaviour and the changes that they make to the habitat will be carefully monitored to see what happens.  Based on experiences at other sites where beavers have been introduced, if present in appropriate population densities, they should manage the scrub in a way that maintains the mix of open areas, reeds and patches of sallow and birch scrub, which would be ideal for maximizing biodiversity on the site.  The bad news for nature watchers is that beavers are mostly nocturnal so it will not be possible to see them during a normal visit to the reserve but it will be possible to see night time infrared video recordings on the screens in the visitor centre.

Cors Dyfi in the future

Over the last 25 or so years, Cors Dyfi has changed from an area of clear-felled coniferous forest and recovered to be a special place for wildlife with some exceptional species enjoying a mosaic of bog, reed and scrub.  If this habitat is maintained these species should survive and possibly new species may colonize from surrounding remnants of similar habitat in the area, further enhancing the biodiversity of the reserve.  As has already been mentioned, maintaining the site in its current condition is a challenge due to the natural process of succession and also because of climate change-induced increasing temperatures and changing rainfall patterns, which may lower water levels in the reserve.  

With appropriate financial support and a combination of people and special animals like beavers and water buffalo, it should be possible to maintain the habitat mosaic, but the bigger concerns are the external factors outside the control of the team looking after the reserve.  This highlights the difficulty of trying to maintain biodiversity in nature reserves without tackling the environmental degradation that is occurring in the environment at large. The long-term solution for nature recovery requires that the wider natural environment is managed to improve biodiversity rather than just trying to maintain tiny isolated pockets of high-quality habitats.  Furthermore, if we fail to address the climate crisis, over time, Cors Dyfi will become degraded, like many of the other UK peat bogs and upland blanket bogs and may stop functioning properly as a so called ‘nature-based solution’ for carbon sequestration. What's more it would start to release more CO₂ than it is capturing, accelerating the problem rather than mitigating it.  Therefore, it is vital that the causes of the global increases in temperatures that create this risk of degradation are addressed and reversed as fast as possible, both to protect them so that they help mitigate against the increase in global CO₂ but also to maintain and enhance the often exceptional biodiversity of these sites. 

How can we help?

We all need to support the effort to recover the biodiversity of our environment and this involves continuing to encourage activities designed to protect and enhance the quality of special habitats like Cors Dyfi as well as  initiatives in the wider countryside. However, we also need to think about how, as individuals, we can make changes to reduce our own carbon footprints and help address the climate crisis.  Governments and industry can implement policies that will make a difference but ultimately, we will all have to make changes to the way we live, if as a society, we are to achieve the ambition to limit the expected rise in global temperature.  

The new Dyfi Wildlife Centre at the reserve is an excellent example of sustainable development and a demonstration of how the creation and operation of a built environment can minimize its carbon footprint (by recycling building materials, installing hyper-efficient heating systems and generating electricity through solar panels) and ultimately be ‘net carbon negative’ (supporting a net reduction in overall CO₂ levels rather than increasing them). This is a signpost of the type of changes that can help to solve the wider problems that are placing huge stresses on our natural environment.  It is also a great place to visit at any time of year, even when the ospreys are not in residence, providing an opportunity to understand the area and experience a wide range of interesting wildlife as well as excellent cakes!

Happy wildlife watching

Tim

Acknowledgements

Many thanks to Kim and Alex from DWC for taking the time to show me around the reserve and also to all the employees, volunteers and supporters who have helped make Cors Dyfi and the DWC the fantastic place it is today

Disclaimer

Any views or opinions represented in this blog are personal and belong solely to the author and do not represent those of people, institutions or organizations that the author may or may not be associated with in professional or personal capacity, unless explicitly stated