GLYN RHONWY BOTANICAL SURVEY DR ROD GRITTEN PhD PGCE CBiol MSB GRITTEN ECOLOGY
1.0 METHODOLOGY Botanical surveys of the Glyn Rhonwy Quarry complex were carried out on a number of occasions during the spring and summer of 2011. This included a Phase 1 survey. A Phase 1 map (Map 2) was generated from these surveys and each of the principle plant communities was further surveyed to at least Phase 2 standard. Notable plant assemblages or species were further described separately as Target Notes (TN). The current ecological status of all the plant communities is further described with notes on current management and possible future (enhancement) management The current surveys covered all plant groups with the exception of lichens which will be dealt with elsewhere. In addition, dedicated plant surveys were carried out of six out of eight of the quarry voids (QV), three were capable of access by walking (QV2, QV3 and QV6)and three by abseiling (QV1, QV4 and QV5) (see Map 1). Two of the voids were either considered to be too dangerous to enter by conventional rope access (QV3a) or access permission was not obtained (QV7). Botanical surveys were conducted as samples within an area approximately 400 metres to the north and south of a hypothetical mid-line linking the six main quarry voids (see Map 1), although particular attention was given to the areas immediately around the Quarry Voids (marked in red on Map 1). Finally, reference is made to the Cyngor Gwynedd Local Biodiversity Action Plan (LBAP) and the Section 42 list of the NERC (2006) Act to put the results of the botanical surveys into a local and national context. Map 1: The Quarry Voids. The main survey area falls within the red boundary. 2.0 RESULTS: PHASE 1 SURVEY The results of the Phase 1 survey are summarised in Map 2. The Quarry Voids are located approximately along a west-east axis and are generally surrounded by enormous slate waste tips. These are more or less vegetated according to their age (older tips are more vegetated) and their composition. For tips
Map 2: Phase 1 map of the survey area. with larger rock waste tend to be less vegetated than those with a higher proportion of interstitial fines or a high proportion of over-burden. As a generality, the plant communities on the site fall into a quite definitive gradation based more or less on the varying altitudinal levels of the site. To the far west QV1 is situated at 350 metres asl falling to QV6 at approximately 150 metres asl. The upland (western) end is fairly intensively sheep grazed and suffers from a colder, windier climate than the lower (eastern) end. As a result, the more upland areas are characterised by acid grassland and heath communities while lower down the area is considerably more wooded with native broadleaved woodland predominating. Grazing levels at the lower wooded end are substantially lower. Broadly speaking, this transition along the west-east access from heathland to woodland is also reflected in the vegetation assemblages within the quarry voids themselves, though this is also affected by the accessibility of the different quarry voids to sheep grazing pressure. Interestingly, the bryophyte distribution also reflects the altitudinal gradient as well, the western species being more upland in character while the eastern species being more typical of woodland habitats. 3.0 RESULTS: PHASE 2 SURVEY Each of the broad plant communities identified in the Phase 1 survey were further surveyed to detailed Phase 2 level and these are described below. 3.1 Dry Heath/Acid Grassland Mosaic. The acid grassland (Phase 1 code: B.1.1) to the upper (western) limit of the study area is marked as a on Map 2, the majority of which is situated to the south of QV1 and QV2. While these areas of acid grassland form a more or less discrete
community when compared to the surrounding heath, in practice they form quite a complex mosaic of different grassland types and include NVC: U4 Festuca ovina- Agrostis capillaris-galium saxatile grassland, U5 Nardus stricta-galium saxatile grassland and U6 Juncus squarrosus-festuca ovina grassland. Species noted here include Agrostis capillaris, Festuca ovina, Potentilla erecta, Galium saxatile, Polygala serpyllifolia, Anthoxanthum odoratum, Nardus stricta, Juncus effusus, Sedum anglicum, Digitalis purpurea, Lotus corniculatus, Carex binervis, and C. pilulifera. Mosses found here are typical of this habitat and include Rhytidiadelphus squarrosus, Pleurozium schreberi, Hylocomium splendens and the moss Racomitrium cannescens agg. which is more typical of the scree (slate waste) habitat and must come from the nearby tips. This acid grassland is also showing a transition to dry heath (Phase 1 code: D5) typified by the incursion of patches of Calluna vulgaris, Empetrum nigrum, Vaccinium myrtillus, Erica cinerea and Ulex gallii. Additional bryophyte species noted within the more heathy patches include Racomitrium lanuginosum, Hypnum jutlandicum and Dicranum scoparium. While neither the acid grassland nor the heathy colonising vegetation are of any particular species diversity, the presence of Fir Clubmoss (Huperzia selago) is of some interest. The fact that this acid grassland is slowly reverting to dry heath is testimony to the fact that the grazing pressure is quite low. This is also exemplified by the presence of a number of colonising Rowan trees (Sorbus aucuparia). The whole of this area has been mapped on the Phase 1 map (see Map 2) as Phase 1 code: D5 (Dry heath/acid grassland mosaic) since there are some areas of discrete dry heath, areas of acid grassland and areas of a mosaic of both.
3.2 Dry Heath There is a large area of dry heath (Phase 1 code: D.1.1) lying to the north of QV1 and QV2 (see Photo 1) which is marked as b on Map 2. This corresponds to Photo 1: The large area of dry heath to the north of QV1 and QV2. NVC: H8 Calluna vulgaris-ulex gallii heath and is typical of so-called lowland heath found in much of the coastal areas of western Britain. It is dominated by Calluna vulgaris, Erica cinerea, Vaccinium myrtillus, Ulex gallii and Empetrum nigrum which is unusually abundant on this mountain. Other species struggling to push through the dense heath mat include Potentilla erecta, Festuca ovina, Deschampsia flexuosa and Nardus stricta. The mosses Rhytidiadelphus loreus, Pleurozium schreberi, Hylocomium splendens and Hypnum jutlandicum are present in some abundance. The heath is dotted with ancient quarrying trial pits many of which have been fenced off from sheep, allowing the establishment of Rowan. 3.3 Wet Heath This is an area to the west of the group of small enclosed pastures known as Pen-y-bwlch marked as c on Map 2. It lies to the south of QV2. It corresponds most closely to NVC: M15 Scirpus cespitosus-erica tetralix wet heath suggesting an underlying shallow peat layer which impedes the drainage to some extent. Though somewhat grassy, it has a diverse assemblage of species, notably Nardus stricta, Potentilla erecta, Anthoxanthum odoratum, Vaccinium myrtillus, Festuca ovina, Carex panicea, C. pilulifera, C. binervis, C. nigra, Galium saxatile, Danthonia decumbens, Luzula campestris, Calluna vulgaris, Erica tetralix, Polygala serpyllifolia, Trichophorum germanicum, Deschampsia flexuosa, Juncus squarrosus and Empetrum nigrum. The following bryophytes were also noted: Hypnum jutlandicum, Rhytidiadelphus squarrosus, R. loreus, Pleurozium schreberi, Racomitrium lanuginosum, Sphagnum capillifolium, Polytrichum strictum and Leucobryum glaucum. It is quite heavily grazed which explains the high proportion of graminoids present in the sward. This wet heath is illustrated in Photo 2.
Photo 2: The area of heavily grazed wet heath to the south of QV2. 3.4 Semi-improved Pastures This area of small enclosures is all that remains of the smallholding known as Pen-y-bwlch which is made up of heavily sheep-grazed semi-improved neutral acid grassland. It is marked as d on Map 2 and lies to the southeast of QV2. Photo 3, taken on 31 st May 2011, shows how the sheep tend to concentrate their grazing there. It is likely such pastures will have a reasonably diverse Wax Cap assemblage (see elsewhere in this report). The small fields, about twenty in all, are bordered by dilapidated stone walls. Photo 3: Heavily sheep-grazed semi-improved acid grassland ( d ).
These enclosures correspond to NVC:U4 Festuca ovina-agrostis capillaris- Galium saxatile grassland and are typified by being close-grazed with Juncus effusus and Cirsium palustre over-topping the sward. Species noted here include Agrostis capillaris, Luzula campestris, Cerastium fontanum, Trifolium repens, Achillea millefolium, Anthoxanthum odoratum, Urtica dioica, Conopodium majus, Galium saxatile, Ranunculus repens, R. bulbosus, Rumex acetosa, R. acetosella, Bellis perennis, Cirsium vulgare, Festuca ovina, Potentilla erecta and Veronica serpyllifolia. The moss Rhytidiadelphus squarrosus is ubiquitous throughout. 3.5 Quarry Spoil Tips The entire survey area (and frequently some areas beyond) is dominated by enormous tips composed of waste slate and over-burden (see Photo 4). These have all been marked on Map 2 as Phase 1 code: I.2.2 and the letter e where they were surveyed. Photo 4: Typical quarry spoil tips with encroaching heath. As has already been mentioned in 2.0 above, these quarry spoil heaps vary somewhat in their floristic composition depending on a number of different factors. Firstly, where the tip is composed principally of over-burden, the soil content is high and the vegetation trends towards dry heath as described in 3.2 above. Secondly, in contrast, tips that are more blocky in their composition tend to have little integral soil or fines and are generally little vegetated as a result, apart from a primary colonising epilithic lichens (see elsewhere in this document). This trend is also evident in the age of the spoil tips: older tips tend to be more vegetated whereas younger tips tend to be less so. As a useful generalisation, the slate tips are man-made bare habitats waiting to be colonised by plants and over time become increasingly vegetated. With time too, senescent colonising plants contribute to soil formation on the tips so that eventually little slate waste is exposed. For the sake of convenience, all the slate tips have been described as one habitat except where their flora is of particular note.
Although the slate waste tips are a man-made habitats, their colonising floristic composition is most akin to NVC: U21 Cryptogramma crispa-deschampsia flexuosa acid scree community, where the fern Cryptogramma crispa is frequently found (see Photo 5). Photo 5: Parsley Fern growing on a waste slate tip. Walls, inclines and ruined quarry buildings have a similar flora to the tips and are included here in the following species lists. As such, the flora tends to be predominantly made up of lower plants dominated by bryophytes (see Photo 6). These include Pleurozium schreberi, Hylocomium splendens, Dicranum scoparium, Polytrichum piliferum (in some abundance), P.juniperinum, Polytrichastrum formosum, Hypnum jutlandicum, H. cupressiforme, Racomitrium lanuginosum, R. canescens, R. fasciculare, R. heterostichum, Lophozia sudetica, Campylopus atrovirens, C. flexuosa, Pogonatum urnigerum, Diplophyllum albicans, Ptilidium ciliare, Weissia controversa, Rhytidiadelphus loreus, Ptychomitrium polyphyllum, Dicranella heteromalla, D. varia, Grimmia donniana, Mnium hornum, Bartramia pomiformis, Pseudotaxiphyllum elegans, Isothecium myosuroides var. brachythecioides and Breutelia chrysocoma. These bryophytes are typical of acid substrates and are common in similar habitats all over North Wales.
Photo 6: Bryophyte colonisation of quarry tips. Where soil is beginning to develop, the bryophyte dominated flora gives way to NVC: U1 Festuca ovina-agrostis capillaris-rumex acetosella grassland where the soils are shallow and prone to seasonal desiccation, eventually succeeding to U4 Festuca ovina-agrostis capillaris-galium saxatile grassland as small patches between the blockier tips develop. Species noted in this establishing grassland include Deschampsia flexuosa, Sedum anglicum, Festuca ovina, Galium saxatile, Aira praecox, Hypochoeris radicata, Rumex acetosella, Digitalis purpurea, Lotus corniculatus, Polypodium vulgare, Asplenium trichomanes, A. adiantum-nigrum, Oxalis acetosella, Viola riviniana, Potentilla sterilis, Taraxacum officinale agg., Fragaria vesca, Dryopteris filix-mas, D. affinis, especially where sheep grazing is infrequent, D. oreades, Teucrium scorodonia, Plantago lanceolata, Achillea millefolium, Trifolium repens, Luzula campestris, Pilosella officinarum, Veronica officinalis, Geranium molle, Campanula rotundifolia, Senecio viscosus and the invasive New Zealand Willowherb (Epilobium brunnescens). As has already been mentioned above, some heathy elements are often found colonising the developing grasslands including Calluna vulgaris, Vaccinium myrtillus, Erica cinerea and Ulex gallii (see Photo 7). In parts, especially where the terrain is inaccessible to sheep grazing, tree and shrub species are colonising the tips, namely Salix cinerea, Betula pubescens, Sorbus aucuparia and Crataegus monogyna. Of some interest are plants that rely on a more base-rich soil and these are found often at the base of walls which have been built with a lime mortar. Plants such as Thymus polytrichus, Carex caryophyllea and the bryophytes Conocephalum conicum and Rhytidiadelphus triquetrus are examples.
Photo 7: Older tips and those with a higher proportion of over-burden eventually become colonised with more heathy vegetation. 3.6 Wet Heath/Acid Grassland Mosaic This is a distinctive habitat located down slope of the very large waste tip between QV2 and QV3 and is marked as f on Map 2. It extends some distance to the south of the intersection between the two quarry voids. It corresponds most closely to NVC: M15 Scirpus cespitosus-erica tetralix wet heath and contains in addition a number of flushes where water from upslope comes to the surface. Most of these flushes (Phase 1 code: E.2.1) are acidic in nature but somewhat curiously, a number of them, generally the smaller ones, are moderately mineral rich, as indicated by the presence of quite extensive patches of Chrysosplenium oppositifolium and the mosses Scorpidium scorpioides, S. revolvens, Calliergonella cuspidata and Campylium stellatum. Although the predominant geology of the locality is composed of acidic rhyolites and slates, the presence of sufficient mineral deposits to allow the growth of such moss species must be due to their exposure during the quarrying process. Where there is a strong flow of acidic water through this wet heath area, for example at the toe of the huge slate tip marked as e in Map 2, Juncus effusus and J. acutiflorus rushes become dominant suggesting NVC: M23 Juncus effusus/acutiflorus-galium palustre rush pasture. The whole area is a complex mosaic of acid grassland (see 3.1 above), wet heath and flushes but has been mapped as simply Phase 1 code: D6 for convenience. Photo 8 illustrates this area.
Photo 8: Typical wet heath/acid grassland mosaic above QV3. Note Salix cinerea to the right of the picture. The following additional species were noted in this area: Anthoxanthum odoratum, Potentilla erecta, Rumex acetosa, Cirsium palustre, Ranunculus acris, R. flammula, Cardamine pratensis, Stellaria alsine, Lotus pedunculatus, Carex panicea, C. echinata, C. nigra, Vaccinium myrtillus, Calluna vulgaris, Festuca ovina, Nardus stricta, Trichophorum germanicum, Eriophorum angustifolium, E. vaginatum, Polygala serpyllifolia, Oreopteris limbosperma, Pedicularis sylvatica, Viola palustris, Blechnum spicant, Juncus squarrosus, J. bufonius, Narthecium ossifragum, Pinguicula vulgaris, Drosera rotundifolia and Salix cinerea which is in some abundance along one of the larger streams flowing through this habitat. The following bryophytes were also noted: Kindbergia praelonga, Philonotis fontana, Sphagnum fallax, S. capillifolium, S. subnitens, S. palustre and S. denticulatum. It must be said that this habitat is probably the richest within the study area and would certainly repay further more detailed survey. Other similar wet heath/acid grassland mosaic areas are found to the north of QV4 and QV5 (see Photo 9).
Photo 9: Wet heath/acid grassland mosaic north of QV4. 3.7 Bracken dominated areas On the deeper soils which have been little affected by the past quarrying and tipping operations, Bracken (Pteridium aquilinum) has come to dominate (Phase 1 code: C.1.1). A few of these areas were surveyed and are marked as g on Map 2. Most of these areas correspond to the species-poor sub-community of the NVC: U20 Pteridium aquilinum-galium saxatile community. Few species are able to tolerate the deep shade cast by the dense Bracken fronds and the highly acidic soil that the leaf litter generates. Species noted in this habitat include Agrostis capillaris, Digitalis purpurea, Festuca ovina, Potentilla erecta, Oxalis acetosella and Pleurozium schreberi. Typical Bracken dominated communities are illustrated in Photo 10.
Photo 10: A typical Bracken dominated area. 3.8 Broadleaved woodland and scrub One of the most noticeable vegetation transitions from the top to the bottom of the study area occurs approximately along the 300 metre asl contour line that runs between QV4 and QV5. Above this line, only a few scattered scrubby trees have colonised, for example, Sorbus aucuparia, Betula pubescens and Salix cinerea. Sheep grazing and severe weather inhibits the establishment of woodland as opposed to scrub. However, below this point, especially where sheep grazing has been exclosed by fencing, a more dense woodland has developed. That this woodland is effectively secondary is evidenced generally by the absence of mature Oak trees (Quercus petraea), though seedlings are occasionally found here. A typical secondary woodland of this sort is marked on Map 2 as h (see Photo 11). Although this habitat is in a transitional successional state, it is more than likely trending towards NVC: W17 Quercus petraea-betula pubescens-dicranum majus woodland, well established examples of which are located to the south of QV6 where some of the Oaks have achieved considerable maturity. (Access into some of these woodlands was problematic). Examples of intermediate scrub woodland located throughout the lower Glyn Rhonwy quarry complex and, in particular, within some of the quarry voids (see description of flora within QV5, for example) are best described as NVC: W23 Ulex europaeus-rubus fruticosus scrub where European Gorse is particularly prevalent. Within the woodland marked as h on Map 2, other tree species noted include Salix cinerea, especially in areas of poor drainage, Ilex aquifolium, Fraxinus excelsior, Sorbus aucuparia, Acer pseudoplatanus, Crataegus monogyna and woody shrubs such as Rubus fruticosus, Rosa canina and Hedera helix. Other species found here are Anthoxanthum odoratum, Rhytidiadelphus loreus, R. triquetrus, Isothecium myosuroides, Polytrichastrum formosum, Oxalis acetosella, Pleurozium schreberi, Thuidium tamariscinum, Viola riviniana, Fragaria vesca, Potentilla sterilis,
Photo 11: Typical secondary broadleaved woodland situated to the south of QV4 and QV5. Geranium robertianum, Dryopteris affinis, Umbilicus rupestris, Polypodium vulgare, Deschampsia flexuosa, Carex sylvatica, Hypnum andoi, H. jutlandicum, Lonicera periclymenum, Circaea lutetiana, Frulania dilatata, Ulota crispa, Loeskeobryum brevirostre, Dicranum scoparium, Holcus mollis and Hypericum pulchrum. The mineral-rich flushes mentioned in 3.6 above also come to the surface within this woodland as evidenced by species such as Primula vulgaris, Amphidium mougeotii and Plagiomnium undulatum. However, other water-demanding species such as Filipendula ulmaria and Fissidens taxifolius tend to occur in the more acidic areas. It must be appreciated that developing woodlands of this sort do not always have clear boundaries and, especially at the base of the waste tips, tend to feather upwards somewhat so that species such as Salix cinerea, Betula pubescens and Buddleja davidii are found on the toe of the tips with any ground flora being almost entirely absent. 3.9 Disturbed and Bare Ground Towards the bottom end of the study area around QV6 and QV7, a considerable amount of work has been and is still currently in progress levelling the old waste tips to create a modern industrial/business park. These areas, dotted in between mature broadleaved woodlands are described in Map 2 (marked as i ) as bare ground (Phase 1 code: J.4). At the time of these surveys, work was still continuing. Several areas have already been planted with trees (see Photo 12). The ground in these areas has been landscaped, levelled and covered with crushed slate waste. Several colonising plant species were noted in these sites but apart from the ubiquitous Salix cinerea and Betula pubescens, many of them are best described in this habitat as colonising weed species. Typical examples include:
Photo 12: A typical landscaped and planted old waste tip sites around QV6 and QV7. Buddleja davidii, Potentilla reptans, Veronica officinalis, V. serpyllifolia, V. arvensis, Chamerion angustifolium, Scrophula nodosa, Epilobium montanum, E. brunnescens, Senecio jacobaea, S. vulgaris, Verbascum thapsus, Geum urbanum, Arctium minus, Prunella vulgaris, Anagallis arvensis, Ranunculus repens, Anthoxanthum odoratum, Poa trivialis, Myosotis arvensis, Festuca rubra, Rubus fruticosus, Vicia sativa, Arrhenatherum elatius, Geranium dissectum, Sagina procumbens, Fragaria vesca, Circaea lutetiana, Sonchus asper, Erodium cicutarium and Valerianella locusta. 4.0 RESULTS: TARGET NOTES Only two sites were noted throughout the study area which displayed a particularly interesting floral assemblage. TN1 is situated at SH56226050 at the base of a long incline (see Map 2). This is the partially flooded entrance to a long tunnel that may have provided access to the bottom of QV3a. The tunnel entrance is obscured by shrubs of Crataegus monogyna and Sorbus aucuparia which, together with the flooding, have protected the somewhat base-rich flora from grazing pressure. Other species noted at the entrance to this tunnel were Primula vulgaris, Anemone nemorosa, Athyrium filix-femina, Mentha aquatica, Geranium robertianum, Filipendula ulmaria, Oreopteris limbosperma, Dryopteris affinis, Lysimachia nemorum, Viola riviniana, Potentilla sterilis, Rosa canina, Circaea lutetiana, Plantago lanceolata, Pelia epiphylla and Atrichum undulatum. TN2 was located at the bottom of QV2 and is described in 5.2 below.
5.0 RESULTS: QUARRY VOID SURVEYS 5.1 Quarry Void 1 (QV1) QV1 (see Photo 13) was generally accessed by abseil but a way out was found on foot confirming that this void is sporadically grazed by sheep. The bottom and sides are only sparsely vegetated being made up of exposed fractured slates, shales and waste tips. Despite the shelter that must be afforded by the quarry sides, the vegetation is sparse and generally poorly developed, probably a reflection of the altitude. A small lake is present in the bottom but is clearly extremely oligotrophic judging by the almost total lack of aquatic macrophytes, either littoral or emergent, the flora being confined to a mat of filamentous algae. Trees and shrubs are infrequent being confined to a few Sorbus aucuparia, Picea sitchensis, presumably seeded in from the forestry plantation to the immediate south of the Quarry Void, Crataegus monogyna and somewhat surprisingly, a single Cotonaster x frigidus (?) that must be a garden escape. The vegetation ranges from dry heath/acid grassland mosaic (as described in 3.1 above) to bare quarry spoil colonisers (as described in 3.5 above). Species noted here were Calluna vulgaris, Erica cinerea, Ulex gallii, Deschampsia flexuosa, Cryptogramma crispa, Polypodium vulgare, Agrostis capillaris, Digitalis purpurea, Chamerion angustifolium, Vaccinium myrtillus, Photo 13: QV1 from the south east. Festuca ovina, Empetrum nigrum, Athyrium filix-femina, Dryopteris affinis, D. dilatata, D. oreades, Hypochoeris radicata, Juncus effusus, Senecio jacobaea, Geranium robertianum, Phyllitis scolopendrium, Epilobium montanum, E. brunnescens, Asplenium trichomanes, Sedum anglicum, Urtica dioica, Cirsium palustre, Rumex acetosa, Galium saxatile and the bryophytes Polytrichastrum formosum, Pleurozium schreberi, Polytrichum piliferum, P. commune, Racomitrium fasciculare, R. lanuginosum, Hypnum andoi, Philonotis fontana, Calliergonella cuspidata, Campylopus flexuosus, Pogonatum urnigerum, Homalothecium sericeum and Aneura pinguis.
5.2 Quarry Void 2 (QV2) This Quarry Void is accessible by sheep and comparatively easily entered. Sheep grazing has virtually prevented its colonisation by trees so it has generally a similar flora and appearance to QV1 (see Photo 14), although there are a number of very small Ashes (Fraxinus excelsior) growing on the steep slatey cliff sides, one of which was calculated to be at least 60 years old and so to all intents and purposes bonsaid. There is a great deal of unvegetated exposed rock and spoil. In addition to most of the species already noted in QV1, other species noted in QV2 were Hypnum jutlandicum, Rumex acetosella, Bryum capillare, Ptychomitrium polyphyllum, Dicranum scoparium, Taraxacum officinale agg., Thuidium tamariscinum, Oxalis acetosella, Viola riviniana, Luzula multiflora, Diplophyllum albicans, Fraxinus excelsior, Acer pseudoplatanus, Solidago virgaurea, Campylopus atrovirens and Huperzia selago, the latter species being characteristic of the upland nature of this Quarry Void. A small pool and stream are present here too with the moss Fissidens dubius growing by the side of it. The most interesting part of QV2 is a steep rock face situated next to the larger of the tunnels marked as TN2 on Map 2 (see Photo 15). This face is fed by a continuous water seepage and is clearly somewhat base-rich as evidenced by its interesting flora, notably Oxyria digyna, Arabis hirsuta, Photo 14: QV2 looking east. Amphidium mougeotii and the calcicolous moss Ctenidium molluscum. The grass Festuca vivipara was also found growing here.
Photo 15: The site of TN2 in QV2. 5.3 Quarry Void 3 (QV3) This Quarry Void is effectively two separate but linked workings (see Map 1), the western of which has a small lake. Both voids are accessible to sheep grazing and are comparatively easy to enter. Since they are both accessible to grazing, few trees have established here but there is quite a dense shrub layer in parts consisting of the garden escape Buddleja davidii which is present in so much of these quarry voids and waste tips. The two voids do contain a number of tree and shrub species but they are both more notable for the diversity and abundance of their fern flora. Fern species noted were Cryptogramma crispa, Dryopteris oreades, D. affinis, D. filix-mas, D. dilatata, Polypodium vulgare, Aslpenium viride, A. trichomanes, Athyrium filixfemina and Oreopteris limbosperma which was only found in the eastern void. Other shrub and tree species noted in both voids were Betula pubescens, Rubus fruticosus, Ulex gallii, Quercus petraea, Sorbus aucuparia, Salix aurita, Acer pseudoplatanus, Prunus spinosa, Rosa canina and Crataegus monogyna. Of some interest is a large Swedish Whitebeam (Sorbus intermedia agg) (det. Tim Rich, Welsh National Herbarium) growing on the edge of the eastern void at the far north eastern corner next to the public right of way. The seed source for such an unusual tree must be from a garden comparatively nearby. Other species noted in both voids were Teucrium scorodonia, Erica cinerea, Sedum anglicum, Digitalis purpurea, Anthoxanthum odoratum, Thymus polytrichus,
Potentilla erecta, Fragaria vesca, Galium saxatile, Festuca ovina, Geranium robertianum, Plantago lanceolata, Hypochoeris radicata, Umbilicus rupestris, Calluna vulgaris, Epilobium brunnescens, E. montanum, Holcus lanatus, Vaccinium myrtillus, Oxalis acetosella, Juncus effusus, Rumex acetosella, Lotus corniculatus, Veronica officinalis, Deschampsia flexuosa and Viola riviniana. Bryophytes noted include Polytrichastrum formosum, Thuidium tamariscinum, Rhytidiadelphus loreus, Campylopus flexuosus, Pogonatum urnigerum, Hypnum jutlandicum, H. lacunosum var.lacunosum, H. andoi, Amphidium mougeotii, Mnium hornum, Scapania gracilis, Pleurozium schreberi, Dicranum scoparium, Diplophyllum albicans, Pseudoscleropodium purum, Hylocomium splendens, Fissidens dubius, Ptychomitrium polyphyllum, Racomitrium fasciculare and R. lanuginosum. Species that were only found in the eastern of the two QV3 voids, several of which reflected the wetter nature of this void, included Cardamine pratensis, Chamerion angustifolium, Dactylis glomerata, Salix cinerea, Pilosella officinarum, Senecio jacobaea, Solidago virgaurea, Fraxinus excelsior, Tusilago farfara, Empetrum nigrum, Carex demissa, Ranunculus flammula, Festuca vivipara, Juncus conglomeratus, Cirsium palustre, Urtica dioica, Taraxacum officinale agg. and Hypericum pulchrum. Additional bryophytes included Calliergonella cuspidata, Bryum pseudotriquetrum, B. capillare, Rhytidiadelphus squarrosus, Campylopus atrovirens, Breutalia chrysocoma and Sphagnum capillifolium. 5.4 Quarry Void 4 (QV4) This is the deepest and largest of the Quarry Voids and required a double abseil to explore (see Photo 16). Even then, quite large areas are inaccessible without a more technical rope approach. Nevertheless, several botanical surveys were made and a good assessment of the floristic composition resulted. The bottom of this void at the eastern end has developed a small shrubby woodland which will, if left undisturbed, become more mature in time. Many of the void faces are completely unvegetated, especially on the northern side whereas the southern side is more extensively vegetated, particularly with ferns. The floral composition of QV4 is similar to QV3, namely Betula pubescens, Quercus petraea, Acer pseudoplatanus, Sorbus aucuparia, S.intermedia agg, Buddleja davidii, Salix cinerea, Crataegus monogyna, Rubus fruticosus, Rosa canina agg., Dryopteris affinis, Teucrium scorodonia, Hieracium sp., Solidago virgaurea, Epilobium montanum, E. brunnescens, Chamerion angustifolium, Athyrium filix-femina, Calluna vulgaris, Dryopteris filix-mas, D. oreades, D. dilatata, Erica cinerea, the invasive Rhododendron ponticum, Ulex gallii, Agrostis capillaris, Senecio jacobaea, Geranium robertianum, Hypericum pulchrum, Campanula rotundifolia, Cryptogramma crispa, Asplenium trichomanes, A. viride, Festuca ovina, Anthoxanthum odoratum, Viola riviniana, Deschampsia flexuosa, Centranthus ruber, Hedera helix, Dactylis glomerata, Thymus polytrichus, Lotus corniculatus and the bryophytes Amphidium mougeotii, Racomitrium fasciculare, R. lanuginosum, R. canescens, Rhytidiadelphus triquetrus, R. loreus, Thuidium tamariscinum, Hylocomium splendens, Pseudoscleropodium purum, Hypnum juniperinum, Pleurozium schreberi, Campylopus atrovirens, C. pyriformis, Dicranum scoparium, D. majus, Pogonatum aloides, Bryum capillare, Hypnum andoi, Ptychomitrium polyphyllum and Polytrichastrum formosum.
Photo 16: QV4 looking east. Note developing woodland at base of void. 5.5 Quarry Void 5 (QV5) This void is also divided into two by a hard pillar of slate that has been tunnelled through for access to both sides. The eastern side is quite wooded with trees reaching up to 10 metres tall. While the only access into QV5 is by abseil, a stray sheep had somehow fallen in and was trapped in the void. However, signs of grazing were minimal, hence the tree growth. Being next to a small back road from Llanberis to the east of the quarry, a large amount of household rubbish had been dumped in here. As with the other Quarry Voids surveyed, the flora was somewhat uninteresting. Species noted here include Betula pubescens, Salix cinerea, Fagus sylvatica, Fraxinus excelsior, Corylus avellana, Sorbus aucuparia, S. intermedia agg, Crataegus monogyna, Ilex aquifolium, Quercus petraea, Rubus fruticosus, Buddleja davidii, Ulex gallii, Dryopteris affinis, D. filix-mas, D. dilatata, Asplenium trichomanes, Teucrium scorodonia, Geranium robertianum, Epilobium montanum, E. brunnescens, Senecio jacobaea, Holcus mollis, Hedera helix, Urtica dioica, Brachypodium sylvaticum, Agrostis capillaris, Calluna vulgaris, Rosa canina, Fragaria vesca, Hypericum pulchrum, Erica tetralix, E. cinerea, Ranunculus repens, Cirsium vulgare, Sedum anglicum, Veronica officinalis, Polypodium vulgare, Athyrium filix-femina, Filipendula ulmaria, Circaea lutetiana, Digitalis purpurea, Deschampsia flexuosa and a small patch of Soleirolia soleirolii which would probably have been dumped here. Bryophytes found here include Thuidium tamariscinum, Dicranum scoparium, Lophocolea bidentata, Rhytidiadelphus loreus, R. triquetrus, Calliergonella cuspidata, Amphidium mougeotii, Fissidens dubius, Pleurozium schreberi, Hypnum andoi, Homalothecium sericeum, Racomitrium lanuginosum, Hylocomium splendens, Plagiomnium undulatum, Ptychomitrium polyphyllum, Pelia epiphylla, Polytrichastrum formosum, Dicranum majus, Diplophyllum albicans, Pohlia nutans and Plagiochila porelloides.
5.6 Quarry Void 6 (QV6) Simply from a landscape point of view, this is probably the most interesting of the Quarry Voids since it has a large lake at its base (see Photo 17). The lake, however, is devoid of macrophyte vegetation probably because of copper toxicity but at least two fish species were noted in the lake at the time of the survey. QV6 is accessible to sheep grazing and easy to walk into. There is much bare slate waste piled in the quarry and extensive shrub and tree colonisation. Species noted here were both Betula pubescens and B. pendula (and very likely the hybrid as well), Salix cinerea, Quercus petraea, Fraxinus excelsior, Sorbus intermedia agg., Buddleja davidii, Ulex europaeus and Rubus fruticosus. Photo 17: QV6 with its lake. The absence of emergent macrophytes is probably due to copper toxicity. Other species noted here include Festuca ovina, Teucrium scorodonia, Epilobium brunnescens, E. montanum, Centranthus ruber, Veronica officinalis, Dactylis glomerata, Hedera helix, Calluna vulgaris, Asplenium trichomanes, A. adiantum-nigrum, Cymbalaria muralis, Geranium robertianum, Digitalis purpurea, Plantago lanceolata, Fragaria vesca, Sedum anglicum, Dryopteris affinis, Lonicera periclymenum, Lotus corniculatus, Trifolium dubium, Hypericum pulchrum, Senecio jacobaea, Rosa canina, Cotoneaster horizontalis, Athyrium filix-femina, Ranunculus repens, Poa annua, Juncus effusus, Circaea lutetiana, Umbilicus rupestris, Agrostis capillaris, A. stolonifera, Polypodium vulgare, Solanum dulcamara, Viola riviniana, Danthonia decumbens, Erica cinerea, Pilosella officinarum, Thymus polytrichus, Chamerion angustifolium and Vulpia bromoides. The bryophyte flora was the most interesting of all the Quarry Voids although none of the species found is rare or protected; most of them are common in the locality. Species noted in QV6 were Racomitrium cannescens, R. lanuginosum, R. fasciculare, Pogonatum urnigerum, Ptychomitrium polyphyllum, Dicranum scoparium, Calliergonella cuspidata, Climacium dendroides, Lophocolea bidentata, Hypnum cupressiforme, H. jutlandicum, H. andoi, Antitrichia curtipendula, Thuidium
tamariscinum, Lepidozia reptans, Pleurozium schreberi, Campylopus atrovirens, C. introflexus, C. flexuosus, Mnium hornum, Plagiothecium undulatum, Amphidium mougeotii, Pseudoscleropodium purum, Polytrichastrum formosum and Rhytidiadelphus loreus. 6.O RESULTS: PIPELINE ROUTE(S) At the time of writing, there were two pipeline routes proposed linking the bottom Quarry Voids and the top. By and large, these follow closely a hypothetical line that links all the voids. Separate botanical surveys of these routes were not undertaken since much of the pipeline will run underground. The habitats through and below which these pipeline run have already been described in 3.0 to 3.9 above. 7.0 DISCUSSION As an over view, it must be said that the botany of the study site is comparatively unremarkable. No notable species were found with the exception of TN2 in QV2 described in 5.2 above and no species protected under Schedule 8 of the Wildlife and Countryside Act (1981). Almost the entire site consists of severely disturbed ground with encroaching secondary vegetation. The large area of heath near the top of the site (see 3.2 above) is in good condition and not over-grazed or too frequently burned but is largely outside the area that is likely to be affected by the proposal. The area of mixed wet heath and acid grassland described as f on Map 2 between QV2 and QV3 (see 3.6 above) is of some botanical interest but is also unlikely to be affected by the proposal, being somewhat outwith the route suggested for the pipeline linking the bottom and top Quarry Voids. However, a more detailed survey would be valuable in this area so as to fine-tune any mitigation that might be required. The developing broadleaved woodland towards the bottom end of the site is likely to become a more diverse habitat in time but at this comparatively early stage in its succession, its floristic diversity is still low. The semi-improved pastures described in 3.4 above are of little intrinsic botanical interest as such but may support an interesting Waxcap assemblage (see elsewhere in this report). The Quarry Voids, especially QV2, QV4 and to a lesser extent QV6 are also of some floristic and habitat interest although the diversity of species found is low confirming that successional development is still quite early on in the process. The lost world appearance of these Quarry Voids in particular is worthy of note. Low grazing pressure and shelter from montane weather conditions is creating a remarkable wildlife refuge that can only improve in time. Any future management of the area should primarily focus on this interest. However, the most interesting aspect of the site is best not considered as individual habitats, at least in floristic terms, rather it is the process whereby nature is recolonising a severely man-degraded landscape. Despite a long history of sheep grazing and the harsh weather conditions, it is notable that bare habitats such as slate tips do in fact trend towards a stable plant community, albeit slowly. It is poignant to
note that the Snowdonia National Park s Biodiversity Action Plan (Snowdonia National Park Authority (1998)) describes acidic screes as one of the most interesting habitats in North Wales. This is in part due to the abundance of Parsley Fern (Cryptogramma crispa), a species which is very rare in Europe but is becoming increasingly common on the Glyn Rhonwy slate tips. These man-made habitats should be considered as developing, although artificial, acidic screes. It is emphasised here that care should be taken to disturb these rather fragile habitats as little as possible during the course of construction works. Having said that, any future disturbance would paradoxically result in further bare-ground colonisation opportunities. The ecological value of sites such as Glyn Rhonwy should also be considered in the context of both Gwynedd s Local Biodiversity Action Plan (LBAP) (Natur Gwynedd (2004)) and the Section 42 list of Priority Habitats and Species as part of the Natural Environment and Rural Communities Act (2006). Habitats featured in Gwynedd s LBAP that were noted at Glyn Rhonwy include Upland Woodland (in this context still developing); Scrub Woodland; Lowland Heathland (as opposed to Upland Heathland in which Ulex gallii is absent); Inland Rock, Quarries, Mines and Screes (plan still to be published); Lowland Wetlands and Lowland Dry Acid Grassland. No Gwynedd LBAP plant species were found in the Quarry. Section 42 habitats of Priority Importance found at Glyn Rhonwy were Upland Oakwood, Lowland Dry Acid Grassland, Lowland Heathland, Upland Flushes, Fens and Swamps; Oligotrophic Lakes and Open Mosaic Habitats on Previously Developed Land (OMHOPDL). The latter habitat must be considered the most interesting on the site but is somewhat difficult to define adequately (see definition in JNCC website (July 2010)). Its main features are the presence of bare ground, a history of disturbance, the presence of vegetation in early successive stages (grassland to heath) and a range of successional vegetation. Glyn Rhonwy clearly has all these attributes The value of the Glyn Rhonwy site, therefore, must be largely considered as an educational one rather than for any intrinsic botanical interest in its own right. (The bird interest of the site should also be considered and this will be dealt with elsewhere). Any future development should focus on opportunities for the safe study of the ecological successional processes that are so well displayed here, particularly within the more inaccessible Quarry Voids and on the tips themselves. However, put in context, sites such as Glyn Rhonwy, which so aptly exhibit the Section 42 OMHOPDL habitat, are abundant in the uplands of North Wales. A careful mitigation plan for the present development proposal should take into account this habitat particularly but also the other LBAP and Section 42 habitats. 8.0 FURTHER SURVEY, RECOMMENDATIONS AND CONCLUSIONS This botanical survey has been carried out thoroughly over a period of several days spaced throughout the main plant season and it is, therefore, unlikely many species present in the quarry complex have been overlooked. However, once detailed engineering protocols have been finalised, it is recommended that more detailed
surveys of the affected Quarry Voids are carried out. (It would be of academic interest to undertake further abseil surveys of some of the more promising Quarry Void cliffs, eg QV4. It may also been considered expedient to undertake surveys of QV3a and QV7. It is also recommended that the wet heath/acid grassland/flushed area mentioned in 3.6 above ( f on Map 2) is subjected to a more detailed survey. Future management of the site should include ensuring that all the Quarry Voids are isolated from sheep grazing, both for animal welfare reasons as well as for their developing ecological interest. It must be concluded that the Glyn Rhonwy Quarry complex is not an intrinsically important botanical site since no protected species were found here. For that reason, it is unlikely the site would ever be considered for nature conservation designation, as least for its plant assemblages. However, its value must lie in the comparatively recent interest that is being shown in sites described in the NERC (2006) Section 42 list as Open Mosaic Habitats on Previously Developed Land (OMHOPDL). It is considered that interest must be being focussed upon such habitats for their clear demonstration of ecological succession from disturbed land towards more climax vegetation. The educational value of Glyn Rhonwy must be in this sphere and any development undertaken here should a) be mitigated to prevent untoward damage of these features and b) endeavour to incorporate facilities for the safe study and appreciation of these features/processes.