Royal Forest of Dean home to rare fern

Royal Forest of Dean home to rare fern

Over the last few years BSG Ecology has provided ecological support to a heritage lottery-funded project aimed at restoring Whitecliff Furnace, a Scheduled Ancient Monument near Coleford in the Royal Forest of Dean.  Our work to date has included detailed bat surveys to inform working methods which allowed the stabilization of the main furnace flue and re-pointing of masonry, whilst avoiding the need for a European Protected Species license.

The most recent phase of the project, led by Kate Biggs from The Wye Valley AONB Partnership, involves the stabilization of a crumbling wall and rock exposure, and reconsolidation of masonry associated with a secondary furnace abutment adjacent to the main blast furnace.

BSG Ecology’s role in the project

The AONB Partnership brought in multidisciplinary consultants Opus International to provide advice on the renovation works.  BSG has worked closely with Opus on many heritage projects and an excellent working relationship has developed.  Opus therefore asked BSG to provide ecological support for the next phase of works.  Due to the presence of potential roost sites within the rock exposure and  furnace abutment, the presence of known bat roosts in structures immediately adjacent and the potential of the proposed works to affect any bats that might be present, we advised that surveys to establish the presence or absence of bats should be undertaken.

We once again teamed up with Ascend, a specialist roped access company, to send Steph Boocock abseiling over the wall, equipped with a video endoscope and torch.

A surprise discovery

During the inspection of the abutment a small fern was noted growing from the lime mortar (as well as a number of fresh bat droppings).  Steph had previously been involved with a restoration project at Chepstow Castle  in south east Wales during which BSG had recorded and designed mitigation for the nationally rare lobed maidenhair spleenwort Asplenium trichomanes spp. pachyrachis.  A number of fronds from the ferns at Whitecliff Furnace were taken as samples and the bat inspection continued.

After consulting identification guides, BSG’s photographic library and a national expert based at the Natural History Museum, Steph was able to confirm that the fern at Whitecliff Furnace was indeed the rare lobed maidenhair spleenwort. This rare subspecies has only been recorded at around twenty sites in the UK and is categorized as near threatened under the International Union for Conservation of Nature and Natural Resources guidelines.

Sensitive working methods

Having successfully resolved a similar issue at Chepstow Castle last year, we are discussing the application of a similar methodology to the furnace abutment at Whitecliff Furnace.  In order to protect the plants during the repointing work, we will mark up their locations to enable contractors to work around them as far as possible.  This approach should enable the conservation of the population of this rare fern without compromising the extent or timing of the renovation works.

With regard to roosting bats, the identification of evidence of roosting (droppings) has triggered the need for further information and BSG will be undertaking more detailed surveys of the structure over the coming months.

Further contribution to conservation

The fronds collected during the roped access inspection have been sent to the UK fern DNA barcoding project run by the Natural History Museum in London.

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