Appendix 4, Varteg Lichens Report
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Lichen Survey for Planning Application at Varteg, Torfaen, S. Wales Watsonian vice-county 35 – Monmouthshire; NGR: c. SO 26 06 J.C.E. Hope 23.viii.2005 Summary The site of the planning application at Varteg was surveyed for lichens, resulting in a total of 96 taxa being recorded. Eight of these are classified as Nationally Scarce in the British Isles but these, as well as all other taxa recorded have been given a conservation evaluation of ‘Least Concern’. None of the species found have ‘International Responsibility’ status or are indicative of high-quality lichen habitats (e.g. ‘ancient woodland’ species). The most significant habitats found on the site were: built structures, small trees, soil in heathy vegetation, stones and small boulders, and worked timber. Eight taxa have been recorded new to Monmouthshire; however it seems likely that this is largely due to a paucity of prior recording effort in the vice-county. Additionally, one lichen found at the site has not been identified as belonging to any known species and probably represents an undescribed species; nevertheless, it is thought unlikely to be of high conservation importance. On the evidence of the survey results, the site is not of national importance for lichens and it is unlikely to be of regional or local importance, although lack of recording from similar habitats in the area makes the regional and local status difficult to gauge with certainty. Introduction The survey reported on here was commissioned by the Glamorgan Power Company in respect of a planning application relating to a site at Varteg, Torfaen, South Wales. The application is for housing development and reclamation of old spoil heaps from coal mining activities. The purpose of the survey is to generate a list of lichen taxa present on the site, and thus to report on the conservation importance of the site for lichens. No previous lichenological fieldwork is known to have been undertaken on the site. Methods The site was visited on the 4th of July 2005. The weather was generally fine with occasional light showers. The survey was of a simple ‘walk about’ style, involving visual search for habitats and substrates of potential interest, followed by detailed scrutiny of these features for lichens. In most cases, material could be identified in the field using a hand lens (and occasionally spot-test chemicals: C = aqueous solution of NaClO as contained in domestic bleach; K = aqueous solution of NaOH). Where necessary, small specimens of lichen were collected for microscopical examination. It should be appreciated that, due to the small size of the organisms, a survey such as this can never be expected to pick up a complete or exhaustive list of species present. However, by judicious targeting of habitats for inspection, it is hoped that the majority of species will be found, and a good impression of the lichenological interest of the site gained. Access to the site was gained via a gate near the southernmost point on the boundary at SO 2638 0568 and the route taken enabled all parts of the site to be seen. The locations of particular features of interest were measured using a Garmin handheld Global Positioning Unit (GPS) unit. For the purposes of recording, the site was divided into 5 areas, numbered 1-5 (roughly in chronological order of first visit). Area 1 The part of site east of 326000 E and south of 206300 N but excluding Area 2, as defined below. Area 2 The area occupied by the deposit mounds and the heathy vegetation that has colonised them, centred on c. SO 2610 0590. Area 3 The whole part of the site lying west of 326000 E Area 4 The whole part of the site lying north of 206300 N Area 5 The area of planned housing development, approximately bounded by 326410 E, 326550 E, 205840 N and 206100 N. Lichen nomenclature follows the most recent British Lichen Society checklist (Coppins, 2002). Results An annotated list of lichens found at the site is presented in Table 1. Separate lists for each area, giving grid references for each record, are given in Table 2. The survey has yielded 96 named lichen taxa as well as one lichen, not recognised as belonging to any known species, that probably represents an undescribed species in the genus Psoroglaena. The most significant habitats found on the site were: built structures (old buildings, walls and tracks), lignum of wooden fenceposts and upended railway sleepers (used as gateposts), soil in heathy vegetation, stones and small boulders (some naturally occurring, others probably deposited by people), and small trees—mainly hawthorn (Crataegus monogyna) and elder (Sambucus nigra). One birch tree (Betula sp.) was examined but was found to be virtually devoid of lichens. Most of the ground is covered by grassy vegetation, which presents few niches for lichens to grow in, so the habitat features mentioned above support almost the lichens on the site. Conservation Evaluation Of the 96 taxa recorded in the survey, eight are classified as Nationally Scarce in the British Isles (i.e. recorded from 16–100 hectads in the British Isles, as of 2002); no taxa of Nationally Rare status were found. All taxa recorded have a conservation evaluation status of ‘Least Concern’ (see Woods and Coppins, 2002), with the exception of the unnamed Psoroglaena. None of the species found have ‘International Responsibility’ status (see Woods and Coppins, 2002). or are particularly indicative of high-quality lichen habitats (e.g. ‘ancient woodland’ species; see Coppins and Coppins, 2002). Eight of the named taxa have been recorded as new to Monmouthshire; however it seems likely that this is largely due to a paucity of prior recording effort in the vice-county. For example, one of these species is Peltigera membranacea which is very common throughout most of Britain in damp grasslands or woods; another is Xanthoria ucrainica – also a common species but currently under-recorded, having being separated from X. candelaria only recently. Some of the Nationally Scarce taxa are likely to be under-recorded generally; for example the Bacidia species are inconspicuous and require microscopic examination. They may be reasonably typical of urban and post-industrial sites, which tend to be neglected by lichenologists. Two of the species, Fellhanera bouteillei and Punctelia ulophylla are reported to be increasing. It seems likely that few if any of the Nationally Scarce species are as restricted as their current known distributions indicate. In terms of lichen habitats present, none can be considered exceptional. The rock exposure is of very limited extent except for the deposit mounds, which are probably not stable enough to support diverse lichen communities. It is likely that if left, these deposit mounds would be colonised by vascular plants before good saxicolous communities could develop. The trees are rather young to support noteworthy epiphytic communities, and their potential is limited by the lack of old trees and woodland in the vicinity and by legacy effects of industrial pollution. This last effect is evident from the abundance of Lecanora conizaeoides on much of the exposed lignum. Recent decades have seen a significant amelioration in atmospheric sulphur dioxide levels across much of Britain (e.g. Bates et al., 2001)– local evidence of this at Varteg can be seen in the small quantity of the relatively sensitive species Flavoparmelia caperata and Usnea subfloridana present (see Hawksworth and Rose, 1970). Nevertheless, it is likely that much of post-industrial South Wales is still impoverished, especially of the most sensitive species, and it may be many decades or centuries before epiphytic communities of a ‘natural character’ can develop. The site can be considered to be not of national importance, on account of the lack of threatened species or quality habitats. The regional and local importance of the site is more difficult to gauge because of limited information on comparable sites in the area. Based on very general impressions of the habitats on the site and the surrounding area it seems likely that most of the species present at Varteg will be present elsewhere in the vicinity; but of course this is impossible to say with certainty unless more field survey is carried out. Recommendations and mitigation Because there are no species of conservation importance at this site, there are no particular recommendations or mitigating measures that could be considered essential. In general terms, the present lichen communities are a result of relatively undisturbed conditions for the habitat features present, as well as suppression of scrub growth by light grazing. Optimal management for the communities currently present would probably approximate to continuation of the current conditions. The planting of trees to create new woodland is a popular means of mitigation for new developments, but would be doubtfully beneficial in this case. More appropriate would be planting of very limited numbers of well-spaced trees in hedgerows or beside tracks—particularly as replacements for any that have to be removed as part of the works. Species choice would reflect the tree species already present on site, but could additionally include oak (Quercus robur/petraea) to provide habitat for a greater range of lichen species in the future. The best development of terricolous lichen communities is amongst the heathy vegetation colonising the deposit mounds; if possible, some of this vegetation should be retained or, failing this, recreated. Large boulders, if moved, should be reinstated in the same orientation as originally found. Table 1 Annotated list of lichen taxa recorded from site of planning application at Varteg, Torfaen, South Wales. Watsonian vice-county 35 – Monmouthshire; NGR: c. SO 26 06 Annotations in Table Substrata: Cl = Calluna; Co = concrete or cement; Ct = Crataegus; L = lignum (worked timber); Sam = Sambucus; Sx = saxicolous (on rocks); T = terricolous (on soil); Ur = Urtica (dead stems); Ux = Ulex; Vm = Vaccinium myrtillus; -fp = fence post; -rs = railway sleeper.