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Ecology and Management

Ecology and Management of the Alyn Valley Woods.

Sara Hughes B.Sc

  • 1. Formerly a Special Site of Scientific Interest (SSSI) under UK legislation, the Alyn Valley Woods are now a Special Area of Conservation (SAC) protected by EU legislation. The extent of the Alyn Valley Woods SAC is some four and a half kilometres along the valley slopes of the River Alyn and covers some 168.3 hectares. The woods extend in a north north easterly direction from Loggerheads (Grid ref: SJ 197677) to Nant Alyn (Grid ref: SJ197662) and are within the Unitary Authority areas of Denbighshire and Flintshire County Councils. Part of the valley lies within the Clwydian Range Area of Outstanding Natural Beauty (AONB) and is managed by Denbighshire County Council in association with Denbighshire Countryside Services.
  • 2. The Alyn Valley Woods are characterised by three of the habitat types that are listed in Annex I of the SAC Directive: the Tilio Acerion forests of slopes, screes and ravines (class 9180), alluvial forests of Alder (Alnus glutinosa) and Ash (Fraxinus excelsior) (class 91E0) and areas of semi natural dry grassland and scrubland facies on a calcareous substrate (class 6210).
  • 3. Unusually for a SAC there is also plentiful evidence of past human activity. This relates to mineral extraction and quarrying. For example: disused quarries and mine workings; and a “leete” or canal. Today, the “leete” is a footpath that is used by the many visitors who come to the Alyn Valley for recreational purposes.
  • 4 The bio-geographical importance of the Alyn Valley Woods 4.1 A primary consideration in designating the Alyn Valley woods as a SAC was the contribution that the site made to the conservation of some of the habitats that are found within the Atlantic Bio geographical Region of Europe. This region extends from northern Portugal, along the northern shores of Spain, north-western France and northern Belgium together with the western areas of Germany, the Netherlands, and Denmark; the UK and Ireland.

  • 5. The habitats of Alyn Valley Woods
  • 5.1 Within the Annex I habitat types in the UK, 23 are particularly at risk and have been given “priority” status. These habitats are only to be found in the countries of the European Union and as a consequence their importance is reflected in the Habitat Directive. These “priority” habitats should underpin the selection of many of the SACs (Article 4) be the focus of conservation (Article 6) and be monitored (Article 11) The woods in the Alyn Valley feature two of these “priority” habitat types: the Tilio-Acerion forests (79.94% cover) and the alluvial forests with Alder and Ash (2.8% cover)
  • 5.2 Contained in the Tilio-Acerion forest type of the Alyn Valley are NVC Woodland type W8: Ash -Field Maple-Dog Mercury (Fraxinus excelsior-Acer campestris-Mercuralis perennis) and NVC W9: Ash – Mountain Ash – Dog Mercury (Fraxinus excelsior-Sorbus acuparia- Mercuralis perennis). The ground flora also contains several unusual species including Herb paris (Paris quadrifolia) (used as an ancient woodland indicator species), Stinking Hellebore (Helleborus foetidus) the late flowering orchid, Epipactis phyllanthes and Toothwort (Latheraea squmaria). The presence of this habitat type within the Alyn Valley Woods is appreciably above threshold used for the notification of the site as a SSSI and is the primary feature of the site being designated as a SAC, reflecting the scarcity of the habitat and the priority status of the site. The woods contain one of largest areas of continuous coverage of this habitat in both Wales and the UK.
  • 5.3 The Tilio Acerion forest in the Alyn Valley contains a mosaic of other woodland types, including another “priority” habitat: alluvial forests with Alder and Ash. Within the NVC classification they contain the woodland types W5: Alder – Greater Tussock Sedge (Carex paniculata), W6: Alder - Nettle (Urtica dioica) and W7: Alder – Ash – Yellow Pimpernel (Lysimachia nemorum). However, it is only those areas of this habitat type that are found along the floodplain of the river and are predominantly of NVC type W5 and W6 that are regarded as an Annex I habitat.
  • 5.4 The habitat succession that exists within the Alyn Valley Woods also includes a transition from woodland habitat types to that of semi natural dry grassland containing Fescue (Festuca Brometalia) with scrubland facies on calcareous substrates. This habitat type covers 1.07% of the site and whilst a qualifying feature in the selection of the site it neither a primary feature nor one of the UK “priority” habitats.

  • 6. Site Management
  • 6.1 The candidate SACs must also be part of a plan that is both ecologically coherent and may be managed in such a way that the ecological infrastructure is enhanced rather than compromised. The steps that are taken should be aimed at conserving those habitats and / or species for which the site was originally selected. In the Alyn Valley Woods this includes the management of those priority habitats that are present: the Tilio Acerion Forests and the alluvial forests of Alder and Ash as well as the occurrence of semi dry grassland and scrub facies on a calcareous substrate.
  • 6.2 This is well illustrated in the Alyn Valley Woods, particularly within the area of Loggerheads Country Park where a number of areas are managed for differing reasons by Denbighshire Countryside Services. On the semi-natural grassland and scrubland facies that overlie the Carboniferous Limestone, areas have been cleared of trees almost entirely to allow more light through to the ground flora. The aim being not only to stimulate the ground flora but also to encourage the more elusive animal species such as butterflies and moths, snakes and small mammals to become established. By careful management, the creation of these “glades” or corridors has provided opportunities that will assist in the migration and dispersal of species of the area. Butterfly species for example tend to be present in greater numbers in open areas than on the edges of woodland.
  • 6.3 Another aspect of enhancing the ecological infrastructure that can be seen in the Country Park is the rationale behind managing the woodland areas –funded in part by a Forestry Commission Woodlands Grant. Tree species such as Beech (Fagus sylvatica) were introduced into the area during the 1800 and 1900s and conifers - other than Scots Pine (Pinus sylvestris) - in 1965. The presence of these non-endemic species has had a deleterious effect on the number of native trees: Oak (Quercus), Ash (Fraxinus) and Hazel (Corylus), present by blocking out the light. A management programme has been implemented where each year between mid November and March some of the non-native trees are removed to encourage the true native forest and wildlife populations.