Case Study 26

Coed Dol-Fawr, Cwm Rheidol, Cardiganshire

Location and ownership of woodlands

These woodlands lie in Cwm Rheidol, some 2km north-east of Aberffrwd,

Cardiganshire. They extend to ~60ha (150 acres). NGR is SN 705795.

The woodlands are privately-owned by Statkraft, a Norwegian utility company who

also own and operate the adjacent Rheidol valley hydro-electric power scheme. The

woodlands are managed by Sustainable Forest Management (Phil Morgan), a locally-

based forestry consultancy with specialist expertise in continuous-cover forestry.

The entire site is included on the Ancient Woodland Inventory, mapped as being

roughly evenly divided between replanted and semi-natural status. In practice, these

attributes are inter-mingled. These woodlands are not SSSI designated as at 2011.

Significance/ reasons for selection as case-study example

This site has been selected as a case-study within this project for two main reasons:-

1. It is an excellent example of a well-thought through model for the economic use

of timber and woodfuel harvested from a PAWS (or PAWS comparable)

woodland during the process of gradual enhancement. Of particular significance

are the strong local timber processing aspect and the consistent application of the

gradual conversion approach using continuous-cover silvicultural techniques.

2. The wood is typical of many PAWS sites in upland Britain where a new

generation of private owners are inheriting rather neglected post-war crops of

mixed species. There is therefore an informal “demonstration site” role, with the

site used by the Forestry Commission when training PAWS specialists. Given that

these woodlands have been under new ownership and management for some

years, there is the opportunity for others to draw inspiration and to learn lessons.

Owner objectives for management (including PAWS restoration work)

The current owners wish to secure a sustainable financial, silvicultural and ecological

future for their woodlands through appropriate management. The woodlands are

positioned in a steep-sided valley with very considerable tourist significance (heritage

steam railway, riverside walking route, Victorian waterfall attraction etc.), hence

preservation of visual amenity and avoidance of landscape disturbance are paramount.

The owners’ involvement in hydro-electric power generation using the Cwm Rheidol

Reservoir dam below these woods also imposes a protection forestry imperative - the

wood contains some steep, potentially erodible slopes and mining spoil which must

remain immobile to avoid siltation. The owners wish to achieve a gradual restoration

of the PAWS woodlands to predominantly native species composition using CCF

methods to avoid disturbance, and also wish the woodland to produce timber and

woodfuel supplies for local use, contributing to financial and ecological sustainability.

Biophysical characteristics of the site

The site is at 50-320m asl, on very steep convex slopes with a south-westerly aspect.

The climate of the site is warm and very moist [ESC AT5 1608 dd, MD 127 mm

@150m] with a moderate wind regime [DAMS = 12], although upper slopes are more

exposed. The solid geology is Silurian Llandovery slates and shales. The Soil

Association is 611c Manod, an acid podzolic brown-earth soil derived from

Palaeozoic shales. This has a default ESC SMR of Fresh and ESC SNR of Poor. Parts

of the site have been affected by previous lead-mining activity in the district, leaving

deposits of potentially unstable shale-spoil on the surface. Soils can be very shallow.

Terrain is very steep across much of this site, imposing serious restrictions on

mechanised forestry operations, although there are some sections with more gentle

slopes. Some areas have unstable scree/ mining spoil. The owners have considerably

upgraded forest road access within the woodland giving egress to a minor public road

at the foot of the slope. There are Public Rights of Way running along the foot of the

wood and also down through the woodlands from north-west to south-east.

Stand history and current composition

This area would naturally have carried upland acid sessile oak-birch woodland,

traditionally managed on a simple oak coppice system for charcoal and tanbark

production. Woodland of this type, although no longer actively managed, persists on

adjoining farmland and in parts of the case-study site. Following the Second World

War the site was acquired by the Forestry Commission and restocked with a wide

variety of conifers, as part of the rural development scheme associated with the

construction of the Rheidol hydro-electric scheme during the 1950’s. Some plantings

may have been on small open fields within the oak woodland mosaic. The site served

as an arboretum, being unusually species diverse. Main conifers are European/ Hybrid

larch, Douglas fir, lodgepole pine, Weymouth pine (Pinus strobus), western hemlock

and noble fir. Minor components included coastal redwood, ponderosa pine and

Veitch’s silver fir. Accessible stands of larch and Douglas fir appear to have received

some thinning and have developed into a potentially valuable resource, but stands of

noble fir and western hemlock on very steep ground were left un-thinned and have

become drawn-up and potentially unstable. There is some occasional (and increasing)

natural regeneration of conifers, most obviously of western hemlock, across the site.

Evaluation of remnant ancient woodland features and PAWS status

There is a significant surviving resource of oak woodland and associated ground

vegetation on some parts of this site, particularly around the edges, along the lower

slopes and, in mixture with noble fir, on steep upper slopes. Recent fellings of western

hemlock and noble fir have helped to release remnant native trees and ground

vegetation “hotspots” and to encourage incipient native tree regeneration. In less

densely coniferised areas there is a remnant ground vegetation of acid grasses,

bramble, bracken and some ericoids (blaeberry, heather) capable of expansion. This

has been largely shaded out in the very dense stands of western hemlock and fir, but

there remain some spindly oak trees even here, which are being progressively

released. Due to the weak thinning history in the past, there is a resource of deadwood

from density dependent mortality of remnant native trees and over-stocked conifers.

Silvicultural treatments applied to date and intended future silviculture

The current owner and manager acquired the woodlands some 10 years ago in an

under-managed condition and have implemented a regime of restoration management

supported initially by the Forestry Commission’s Woodland Improvement Grant and,

more recently, by the Better Woods for Wales grant scheme. Silvicultural and

ecological restoration have been the main aims, with timber income only expected to

offset the costs of management, given the steep and inaccessible nature of parts of the

site. Throughout the woodland, a gradual PAWS conversion/ enhancement strategy

has been adopted, using the methods of continuous-cover forestry. Better-thinned and

more accessible crops of Douglas fir and larch at the western end of the site have

produced useful timber for local processing and associated income. In the denser

western hemlock stands, a combination of conventional thinning on the lower slopes

and stem-girdling/ chemical thinning on steeper sites has been undertaken to protect

critically-endangered remnant PAWS features and provide scope for their expansion.

On the steep upper slopes, noble fir has had to be felled to waste from among remnant

oak, due to poor access for timber extraction, but foliage from these trees has at times

been harvested to serve the floristry trade and provide some income. Some of the

better Douglas fir, larch, coastal redwood etc may be retained as a productive element

of these woodlands in the long term, whereas the residual western hemlock and noble

fir is essentially serving to preserve a woodland micro-climate to the benefit of oak.

Very spindly remnant oak would be subject to windsnap if suddenly exposed by

felling of surrounding conifers. Occasional western hemlock regeneration is manually

uprooted at present, but this could become more of an issue as these stands mature.

Evaluation of retained timber and woodfuel potential

The main timber potential and carbon storage retained on this site is embodied in the

better conifers - mainly larch and Douglas fir. The silvicultural approach being

adopted will serve to protect and extend that potential. There is a latent value in the

western hemlock and noble fir crops, some of which are of good form, but the

difficult terrain and associated poor economics of harvesting currently limit the

opportunity to extract this material for timber or woodfuel. Changing market prices

and steep-ground harvesting techniques could perhaps release that potential in the

future. As things stand, natural decay of these species will result in carbon release on

site. At present there is no significant harvesting of oak timber from the site due to the

pressure that the oak resource has been under from conifers in recent decades, but

there is no reason why sustainable production of oak timber might not be considered.

Other relevant field examples recorded within the project

This example can most usefully be compared with the other private Welsh woodlands

examined at Ffynone/ Cilgwyn and Coed Caeau-gwynedd, which share the physical

terrain/ access challenges, serious record of under-thinning, recent change of

ownership/ management and productive aspirations all to be seen at Coed Dol-fawr. A

combination of techniques is usually relevant in such situations, including progressive

enhancement using CCF methods on the more accessible/ productive ground and

coupe-felling of dense western hemlock. The girdling/ chemical thinning approach

adopted at Coed Dol-fawr is relatively uncommon, but may be worth considering in

similar contexts elsewhere to extend woodland conditions during the conversion

phase. There are also some parallels with the Woodland Trust examples in Scotland.

Photographic record (see Electronic Appendix for additional/ located images)

Left: distance view of Coed Dol-

Fawr showing blocks of different

conifers and adjoining oakwoods

Right: view from Coed Dol-Fawr

down into Rheidol valley showing

woodland inter-linkages

Left: mature stand of larch on more

productive lower slopes, subject to

gradual thinning operations

Right: recovering ground vegetation

under larch on a better part of the

site following thinning operations

Left: thinning of a promising stand

of maturing Douglas fir - one of the

key timber resources on the site

Right: PAWS restoration work in

dense hemlock using girdling to

retain forest microclimate

Left: mixture of native acid oak

woodland and noble fir on upper

slopes - gradual thinning of the fir

Right: mixture of native acid oak

woodland and noble fir on upper

slopes - gradual thinning of the fir

Left: retained areas of former acid

oak coppice woodland within the

conifer plantations

Right: acid oak woodland habitat

recolonising mining spoil on the

steep upper slope

Left: retained lower slope oak stand

from which western hemlock has

been harvested and removed

Right: gap-phase regeneration

within the site includes oak, ash,

birch and hazel over bramble/ fern