Landscape architect RPS Group and landscape contractors GT Jones are part of a multidisciplinary team contracted for a Welsh Government road project, working with Costain, CH2M and Atkins.
Costain is currently designing and constructing Section 2 of the A465 Heads of the Valleys project, an 8km section of road between Brynmawr and Gilwern in South Wales. There are significant engineering and environmental challenges involved as the road passes through a number of designated sites, including sites of special scientific interest including the Clydach Gorge within the Brecon Beacons National Park and National Nature Reserves.
As part of the project the team is creating new woodland to reinforce the wooded landscape of the gorge and provide foraging habitat for Lesser Horseshoe Bats as well as seeding and growing new sward on the gorge banks.
One particularly delicate operation was the translocation of a Welsh whitebeam, widely considered to be Wales' rarest tree, and which was designated as endangered in 2001, and beech saplings from Cwm Clydach Woodlands to the woodlands.
Naturally occurring beech trees are a rarity in Wales, and those found on the steep-sided slopes of the Cwm Clydach NNR are at the most westerly edge of their range in the UK. Over many generations the strains of Beech trees growing at Cwm Clydach will have adapted in response to these conditions. Translocating beech saplings from within the locality is a way of helping to retain this genetic distinctiveness and to take advantage of stock that is already conditioned for growing successfully within the difficult climate the gorge presents.
This area will be planted with a selection of plants native to Wales. Dingles Nursery in Hereford has so far supplied around 60,000 plants and shrubs for online works and 13,000 for the bat woodlands.
Here contractors have established a woodland habitat, which includes building dead wood piles to provide a home for insects, a food source for bats.
The project partners have also trialled laying an Enkamat erosion control mesh and then also a substrate – Proganics – onto the roadside slopes to provide a soil bed. This should allow better condition for the seed mix to be hydroseeded.
To conserve the limited soil resource on-site they are seeding directly onto ‘as-cut’ faces where possible. Grass establishment on these slopes will be slower but in the longer term they should establish a more diverse sward, Costain said.