BIODIVERSITY ACTION PLAN FOR STANCOMBE QUARRY, SOMERSET

Transcription

1 BIODIVERSITY ACTION PLAN FOR STANCOMBE QUARRY, SOMERSET This document reflects a corporate commitment by Tarmac to develop and implement formal s (BAPs) at its operational sites. Specific targets have been identified that contribute towards the achievement of existing biodiversity objectives described in local and national BAPs and to the conservation of other important habitats and species including all protected species that are not the subject of BAPs. Action for biodiversity is described for specific compartments that have been identified within the site. The Plan describes projects for each compartment to be implemented through a programme of survey (where required), quarry management and restoration. As part of the Anglo-American group of companies, Tarmac biodiversity achievements support a strategic commitment to the implementation of site biodiversity action plans across all the group s activities. The combined effect of these achievements will be to deliver measurable biodiversity achievements at local, national and global levels. 1 INTRODUCTION 1.1 Outline of quarry BAP This document comprises the for, North Somerset. The purpose of this BAP is to provide a single point of reference for the assessment of biodiversity interest in the Quarry, and the development of any future interest at the site through progressive restoration. It reviews the present contribution made by the Quarry to the achievement of national and local BAP Targets and identifies opportunities for further contribution. It also identifies opportunities for conservation of protected and rare species which are not formally included within the BAP process The site, which is approximately 56 ha in size, holds or is in the process of developing the following important habitats:- Lowland mixed deciduous woodland Inland rock exposures Standing water (a pond) Unimproved neutral/basic grassland The site has the potential to develop:- Native broadleaved woodland Calcareous (limestone) grassland ANDREWS WARD ASSOCIATES

2 1.1.4 It is predicted, and will be established by survey, that the site may currently support the following BAP priority species or protected or important species:- scarce invertebrates great crested newt reptiles dunnock song thrush bat species hedgehog dormouse badger The BAP has been drafted on the assumption that these species or groups of species are present. It will be revised as necessary when their status on the site has been established by survey as part of this plan The BAP largely reflects the approved restoration plan which is the subject of planning conditions and is in the process of progressive implementation. Proposed variations in certain details of approved plan, intended to improved delivery of BAP gains, will be submitted to the mineral planning authority for approval prior to implementation. 1.2 Sources of information There has been no ecological survey of the working quarry. A general appraisal of habitat extent, type and quality was undertaken as part of the BAP production process In addition, information on the presence in the locality of statutory or non-statutory nature conservation sites was obtained from Natural England and from the Bristol Regional Environmental Records Centre which also provided records of important and protected species from the site and a 1 km zone around it. 1.3 Existing BAP context The following BAPs are relevant to :- UK s for priority habitats and priority species UK habitat statements for broad habitat types Avon s for priority habitats and priority species. Revisions to habitat and species lists published in June 2007 have been taken into consideration. 1.4 Consultations held Bristol Regional Environmental Records Centre (see above) for statutory and nonstatutory sites, protected and important species ANDREWS WARD ASSOCIATES

3 1.5 Site assessments Other than a general appraisal, none have been undertaken specifically for this BAP but the requirement for additional survey is identified as an action under the Plan. 1.6 Site BAP structure The quarry BAP has four elements:- Part 1 General introduction, summarising the objectives of the BAP and the sources of information on which it is based. Part 2. The Biodiversity Review which present the biological evaluation of the site, with particular reference to habitats and species that are identified as priorities in the UK and local BAPs and other species of importance (e.g. those with legal protection). Part 3. The Implementation Framework which defines the context in which the quarry BAP must be prepared (including such factors as planning conditions), identifies the specific BAP targets for the site restoration and defines the tasks necessary for their achievement. Appendixes. All essential background information including the work programme, which is subject to annual review. 2. BIODIVERSITY REVIEW 2.1 Baseline description This section summarises the results of a general assessment of the site s biodiversity context and values which was made in June Site context Stancombe quarry, which is approximately 56ha in size, is located in the Mendips, close to the village of Flax Bourton and 5 km from the outskirts of Bristol. The surrounding land carries mixed farming and there are substantial blocks of broadleaved and mixed woodland in the locality. A map showing the location of is included at Appendix There are no statutory wildlife sites within 1 km of the site but there are four county Wildlife Sites. They are Bourton Combe, which is Ancient Semi Natural (ASN) woodland, scrub and plantation and abuts the eastern side of the quarry; Breach Wood, also ASN woodland; Cheston Combe and Backwell Hill, ASN woodland and semi-improved neutral grassland; and Hyatt s Wood, which is also ASN woodland There are records of a number of important, BAP priority or protected species present in the vicinity. These include great crested newt, dormouse, several bat species and badgers ANDREWS WARD ASSOCIATES

4 Physiography The site is a limestone quarry developed into the northern slopes of Backwell Hill. It is a RIGS site. Habitats and vegetation contains:- the existing working quarry and mineral processing area, marginal tracks and benches, areas of overburden and processed waste, grassland on soil storage bunds and awaiting stripping, pasture, grassland in glades, self-sown scrub, mixed plantation woodland a pond Preliminary inspection shows little evidence of the development of a limestone flora on worked benches or other areas of undisturbed ground within the quarry. This is unsurprising as there are no obvious donor sites in the vicinity to provide source material for colonisation. However, those areas that have not been colonised by scrub, especially buddleja, are developing a moderately rich flora of common plant species There are several areas of grassland. A soil storage bund on the south-west boundary has some self-sown floristic interest including the uncommon grass-vetchling. The adjacent grassland, which will be lost as the quarry extends southwards, also holds a moderately diverse grassland flora. Small glades within plantation woodland on the north side of the administration block are the richest grasslands floristically A block of woodland on the west side of the site, between the administration offices and the quarry void, is largely Italian alder planted on tipped quarry spoil but it also includes some planted whitebeam and beech. At both ends of the plantation there are small areas of hazel coppice. Several large beech and lime trees stand on lower ground below the north edge of the spoil slope where they appear from their form to have originally grown up on open ground. There is also a scatter of holly, sycamore and wych elm. The ground layer vegetation includes primrose and bluebell but there is no strong evidence of ancient woodland character Other woodland stands to the north of the administration block and on the west and east sides of the quarry are recent plantation, including non-native alders and conifers, and without a true woodland ground-layer vegetation There is considerable buddleja invasion. In the absence of active management, this will probably eventually be replaced by self-sown tree cover but the process is likely to be slow ANDREWS WARD ASSOCIATES

5 Fauna There is no obvious evidence of important invertebrate interest though the grassland areas do support a good range of the less-scarce grassland butterflies including marbled white and skippers. It is possible that the pond is used by amphibians including frogs and newts; common frog is known to breed on the site in an artificial water body. Some of the grassland areas and the part-vegetated benches may hold common lizard and slow-worm, both of which are BAP Priority Species. Based on the types and extent of habitats present, the breeding bird assemblage probably largely comprises common species but may include dunnock and song thrush, both also BAP Priority Species. The site will be used by foraging bats, several of which are Priority Species, and there may be roost potential in rock crevices. Existing biodiversity management commitments There are no specific biodiversity management commitments. 2.2 Evaluation Context The areas of tree planting and small extent of semi-natural woodland have some, rather tenuous, ecological affinities with other woodland in the locality and by conversion to a semi-natural composition they could ultimately contribute to the resource The Mendips formerly held extensive unimproved limestone pastures which supported a characteristic plant community and invertebrate fauna including butterflies now rare. The quarry could be restored to support limestone grassland and possibly some of the associated fauna, though this would need to be achieved by introduction rather than relying on natural colonisation. Site While initial inspection suggest that the interest of the site is limited, there is reasonable diversity in rock exposures and benches, grassland and woodland, and it is possible that a full baseline survey supported by focussed survey for protected species and other important groups will find greater interest The site does contain several BAP Priority Habitats. They are:- Lowland mixed deciduous woodland (small extent), Lowland calcareous grassland (small extent), Inland rock outcrop and scree habitats. None is currently in optimum condition but all three could be managed to develop their biodiversity potential. There are substantial areas of non-operational land in which biodiversity gains could be achieved ANDREWS WARD ASSOCIATES

6 2.2.5 Priority Species considered likely to be present are common lizard, slow-worm, dunnock, song thrush, brown long-eared bat and soprano pipistrelle. The pond could possibly hold great crested newt. Biodiversity compartments To facilitate management of biodiversity objectives, the site has been divided into management compartments as set out at Section SITE BAP IMPLEMENTATION FRAMEWORK 3.1 Factors affecting site BAP implementation Statutory/ legal obligations The planning permission associated with the quarry required the submission of a phased restoration scheme incorporating nature conservation measures to be implemented in order to maximise the value of the restored quarry for wild flora and fauna. Such measures to draw upon and be consistent in scale and character with the appropriate natural characteristics and distinctiveness of the surrounding character area In accordance with the requirements of the site planning permission a restoration scheme was prepared and submitted to North Somerset Council by Wyn Thomas Gordon Lewis in This scheme proposes that the greater part of the site is restored as broad-leaved woodland, with smaller areas of species-rich grassland and rock outcrops and scree slopes, surrounding a large water body with reed fringes. A drawing showing the proposed final restoration scheme is included at Appendix Protected species in addition to breeding birds that may occur in the site include great crested newt, bats, dormice and badgers (which are fully protected at all times), and reptiles (which have limited protection). All birds, their occupied nests and eggs are protected The planning conditions require that the presence of protected species be notified to the mineral planning authority with proposals for mitigation measures to ensure their protection while enabling the continued working of the quarry. Tenancy obligations Tarmac occupy the quarry under the terms of a lease which requires that the quarry is operated and restored in accordance with the restoration scheme approved under the planning permission ANDREWS WARD ASSOCIATES

7 Other factors None known to influence biodiversity management. 3.2 Synopsis of quarry development plan and progressive restoration phase Development plan The drawing included at Appendix 3 shows the approved final layout and design of the quarry under the existing planning permission, which permits extraction up to the end of 2023 and restoration to be completed within 2 years thereafter. The quarry has been in operation since the mid 1950 s and is permitted to work to a depth of 13m AOD (a final total depth from the surface of some 145m). The base of the quarry is presently at 72m AOD. Limestone reserves in the upper and middle benches are currently being worked in a general southerly direction. The most southerly surface area has recently been soil stripped in readiness for working the underlying Limestone reserves. There are circa 28mt of reserves remaining within the planning unit. The aerial photograph at Appendix 4 shows the situation at as at 2007, with soil stripping ongoing. Progressive restoration Restoration is proceeding as set out in the submitted scheme The scheme broadly comprises of 4 restoration phases. Restoration of Phase 1 included placing of loose material and soil forming material on the upper eastern benches and planting with woodland. As the quarry proceeds southwards, restoration to woodland will continue along the eastern upper benches. Species rich grass with small blocks of woodland will be established on the existing scree and loose conglomerate slopes on the west of the quarry. Soils generated in preparation for Phase 2 of the quarry have been used to form a screen bund on the southern boundary, which in due course will be planted in woodland, as a continuation of the screen mound and planting on the western boundary. The next phase of restoration is not likely to take place until circa 2017, with the major restoration works taking place when quarrying has ceased. A drawing showing the final restoration scheme is included at Appendix Core site BAP habitat targets Calcareous (limestone) grassland is a UK and Avon BAP Priority Habitat and its restoration or creation are objectives under the BAPs. At present there is little evidence of the spontaneous development of limestone grassland on worked benches and other potentially suitable land but as there are no nearby sources from which colonisation by the scarcer, characteristic species could easily occur, the process may need assistance by seeding, if possible with material derived from a local site ANDREWS WARD ASSOCIATES

8 3.3.2 The site also holds broadleaved woodland and plantation trees which fall within the Broadleaved Woodland broad habitat type in the UK BAP. Table 1. Schedule of site BAP habitat targets Habitat type Representation on site Habitat extent (approx) Lowland calcareous grassland Not yet present n/a Lowland mixed deciduous Small areas of semi-natural; Approx 6 ha woodland larger extent of non-native Ponds One Small Inland rock outcrop and scree habitats Extensive Approx 10 ha 3.4 Core BAP species targets No BAP Priority Species have been confirmed to use the site though several may do so. They are included in Table 2 together with a number of other species that merit, or require due to legal protection, specific measures. Table 2 Schedule of site BAP species targets Species BAP Location on site Habitat use Status Priority Invertebrates No Throughout all General Probably poorly represented but vegetated areas site is capable of enhancement for many species. Great crested newt Yes Pond and adjacent General Present in locality. Could occur land Reptiles Yes Open areas where there is moderate General Present in locality. Probably occur plant cover. Cont d Dunnock Yes Woodland, tree planting, hedges Song thrush Yes Woodland, tree planting, hedges Bat species Yes Edges of woodland. Trees and rock crevices Hedgehog Yes Woodland and grassland Dormouse Yes Woodland, scrub and hedges Badger No Woodland and grassland Nesting and feeding Nesting and feeding Foraging Roosting General General Foraging. Possible outlier setts Probably breeds. Probably breeds. Not confirmed. Present nearby Not confirmed Not confirmed. Present nearby Present nearby ANDREWS WARD ASSOCIATES

9 3.5 Site BAP project schedule (existing and new interest) The aerial photograph at Appendix 4 identifies the general locations of BAP project work. 1. The working quarry No measures proposed at present. 2. Non-operational areas 2a. Woodland The proposals in the WTGL restoration and aftercare scheme require some limited review in relation to proposed species mixes and management if the best biodiversity outcome is to be achieved. Broad objectives should be to:- Encourage the development of the plantations towards a composition most appropriate to the Mendips. Eradicate non-native species principally conifers and Italian alder. Increase the component of native shrub and tree species of value to dormice and shrub-nesting bird species, both in glades and at plantation edges. Increase the standing and fallen dead wood resource as of value to invertebrates and fungi. Introduce woodland wildflower species with of value to invertebrates. Create sunlit grassy glades. Erect nest boxes and bat boxes to make up for the lack of natural cavities in young woodland. Manage existing mature woodland areas especially to retain mature trees though their natural life spans to become veteran trees. There are some rather narrow woodland strips which will not develop woodland microclimate and therefore have rather limited biodiversity potential. However, as well as providing visual screening, they add to the overall site diversity and probably provide foraging areas for bats once they are restored with native species composition. Objective Action KPI Comment Create seminatural woodland 1. Remove non-native species. 2. Plant with native trees and shrubs. 3. Improve woodland structure glades, dead wood etc. 4. Introduce woodland flora. 5. Install bird and bat boxes 6. Manage older trees to veteran status Developing native woodland character Deal first with areas with access/ educational potential ANDREWS WARD ASSOCIATES

10 2b. Grassland areas Existing grassy areas need to be managed to prevent scrub colonisation. As adjacent trees grow, they will become increasingly shaded and it will be necessary to coppice the adjacent tree cover on the south side in order to reduce its height. This will have incidental benefits for birds and other fauna. It would be advisable to commence experimental creation of small plots of limestone grassland, using and comparing different techniques to find the most costeffective and practicable methods. The cost of seeding, for instance, may be significantly reduced by advance creation of small species-rich plots from which key species can then extend into adjacent land by natural colonisation. Care also needs to be taken in the detail of planting design to ensure that the grassland is capable of management by grazing and is not prohibitively costly to fence. Objective Action KPI Comment Create species-rich grassland 2c. Pond 1. Clear scrub from existing grassland areas. 2. Cut in autumn after seed-set. 3. Control weed species by pulling, cutting or spot-spray Increased calcareous species diversity and value for invertebrates Although the existing pond does not show obvious interest, it should be surveyed for great crested newts prior to any work affecting it or on adjacent land (up to 200m away) that may be used by the species. 2d. Quarry walls, benches Some interest will develop through natural colonisation but buddleja will probably suppress it unless managed by annual clearance. This should be confined to areas with greatest potential to develop floristic interest or native scrub and tree cover. Objective Action KPI Comment Develop native plant cover Colonisation by native plants 1. Control buddleja by annual clearance 2. Permit native species colonisation Where a limestone grassland flora develops, this should be favoured over tree and shrub species. 4. BAP PROJECT REVIEW A work programme has been produced and is given at Appendix 5. It will be subject to annual review to assess progress with individual objectives and to plan and budget to following season s work ANDREWS WARD ASSOCIATES

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12 APPENDIX 1 STANCOMBE QUARRY LOCATION PLAN ANDREWS WARD ASSOCIATES

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14 APPENDIX 2 STANCOMBE QUARRY FINAL RESTORATION SCHEME ANDREWS WARD ASSOCIATES

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16 APPENDIX 3 STANCOMBE QUARRY FINAL LAYOUT AND DESIGN ANDREWS WARD ASSOCIATES

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18 APPENDIX 4 STANCOMBE QUARRY AERIAL PHOTOGRAPH ANDREWS WARD ASSOCIATES

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20 APPENDIX 5 STANCOMBE QUARRY BAP WORK PROGRAMME ANDREWS WARD ASSOCIATES

21 BAP APPENDIX 5. WORK PROGRAMME. ` This work programme will be subject to annual review, updating and extension with new projects as required. Compartment Sub-compartment Summary of Management Actions (refer to Section 3.5 for detail of the required works) 1. The working quarry None proposed Responsibility Timing Year Indicative budget Review date 2. Non-operational land 2a. Woodland 1. Develop detailed woodland management and enhancement proposals and agree any changes to consented scheme with planning authority. To include:- removal of non-native trees, esp. conifers and Italian alder, retention of felled timber as dead wood habitat, identification of felled areas to retain as sunlit glades, planting native shrubs and trees, selected to benefit dormice and shrub-nesting birds, introduction of woodland wildflower species with invertebrate value, erecting bird, dormouse and bat boxes, strategy to develop veteran trees Quarry Manager 2008/9 5, ANDREWS WARD ASSOCIATES

22 BAP 2b. Grassland Clear scrub encroachment from existing grassy areas by office block. Cut annually in September and remove arisings. Develop experimental plots for limestone grassland creation. Review consented restoration scheme to ensure long-term management of grassland areas will be practicable and agree changes with planning authority 2c. Pond Survey for great crested newt and other 2d. Quarry walls and benches - amphibians Identify benches with best potential to develop biodiversity interest and control buddleja. Survey for protected species (incl reptiles, dormouse and badger) that may be present in woodland and grassland to establish baseline and ensure legal compliance. Quarry Manager Estates Manager Estates Manager Quarry Manager Estates Manager Winter Autumn Annual ,000 spring , and ongoing ,000 Annual ANDREWS WARD ASSOCIATES