Botanical Survey -

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Transcript of Botanical Survey -

Date: July 2021
Trewetha Port Isaac
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Disclosure
The information and advice presented within this report is based on the professional and true
opinions of Ecology Partners and is written in accordance with the CIEEM Code of
Professional Conduct.
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2.3 NVC survey 4
5. References 20
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1. Introduction
Ecology Partners were commissioned by Devon and Cornwall Ecology on behalf of Bude - Stratton Town Council (BSTC) in May 2021 to carry out a botanical survey of land surrounding the Storm Tower on Compass Point, Bude. Built as a lookout in 1835, the tower is a Grade II listed stone structure approximately 3.7m wide and just under 7m tall and a prominent local landmark. Due to coastal erosion the cliff edge is c.4 metres away and it is proposed to dismantle the tower and rebuild it on a new site c.100m further inland (at grid reference SS2015106378).
The Storm Tower is situated within Efford Down which is designated as part of both a Special Area of Conservation (SAC) and Site of Special Scientific Interest (SSSI) and supports important areas of maritime grassland and heathland as well as a number of notable species. The purpose of this contract is to survey and assess the habitats present within the areas likely to be affected by the works. The proposals are reviewed and recommendations are made as to how impacts might be minimised.
The survey area focuses on Compass Point, where the tower is situated and the promontory of high ground behind it including the site to which the tower will be relocated c.100m to the east and immediate surrounding areas as well as the proposed access route which follows an existing public footpath along the valley bottom immediately to the south.
The site location and survey area is shown on Map 1, Appendix 1.
2. Methodology
2.1. Personnel
This project has been undertaken by John Sproull MSc, MCIEEM. John is a trained field botanist with over 15 years experience of working as an ecological consultant regularly undertaking NVC and other specialist plant survey and habitat assessment work in Cornwall and other parts of the UK.
2.2. Review of existing data
Prior to undertaking the survey work existing data relating to the site (as listed below) was reviewed to inform the survey:
Information relating to SSSI and SAC designation available on the MAGIC Mapping website (DEFRA, 2021).
Notable vascular plant species recorded within the 1km grid square SS2006 as held by the Environmental Records Centre for Cornwall and the Isles of Scilly (ERCCIS). These records were previously supplied by the client to inform a survey of a nearby site (a proposed new cycle path between Summerleaze – Crooklets also for BSTC).
Cornwall Biodiversity Network desk study data (CBN, 2021).
2.3. NVC survey
A targeted National Vegetation Classification (NVC) survey was undertaken on Tuesday 15th June 2021 to sample and map the main vegetation communities on the headland. A series of quadrats was taken within representative homogeneous stands of vegetation across the
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site. Habitats along the proposed access route either side of an existing public footpath leading up to the tower from Church Path along the valley bottom immediately to the south were also assessed but not surveyed in detail.
A list of the vascular plant species occurring within the main vegetation communities was recorded and records made of any notable species seen during the survey. Point data, including quadrat locations and other notable features were recorded using a Garmin Oregon 750 GPS unit and representative digital photographs were taken. Quadrat data were tabulated in Excel and assigned to community types by reference to the vegetation keys and floristic tables in Rodwell, (1991 et seq) and digitised in QGIS version 3.12.3- Bucureti at 1: 5000.
2.4. Limitations
The survey was undertaken at an appropriate time of year during appropriate dry, warm weather and with free access to all parts of the site.
The NVC system seeks to assign vegetation samples (quadrats) to (sub) communities by assessing the degree to which samples match published descriptions based upon species composition, constancy and abundance. In reality vegetation communities exist on a continuum grading into one another with floristics moderated by a range of factors (such as soil type, altitude, prevailing weather patterns etc.) as well as human intervention. The vegetation at Compass Point shows varying degrees of maritime influence moving inland from the cliff edge with transitions in part mediated by varying degrees of exposure to salt spray deposition and the effects of heavy foot-fall in areas associated with footpaths. Consequently it can be difficult to identify boundaries on the ground, to separate and assign communities within the NVC. As a result it is sometimes necessary to take a ‘best-fit’ approach and / or to map transitional habitats (where elements of more than one NVC community are present).
As per the specification for this contract representative quadrats only were taken of each
dominant habitat type to allow determination of the main plant communities within the NVC using the judgement of the surveyor. The full NVC methodology (Rodwell, 1991 et seq) requires that a minimum of 5 quadrats are taken per (sub) community (this also enables data analysis using appropriate software such as MAVIS).
Notable species were comprehensively sought within quadrats and within areas likely to be impacted by the proposed work but could not be exhaustively searched for across the entire area within the time available. It is also acknowledged that some flowering plant species may not have been visible or readily identifiable at the time of the survey. It remains possible therefore that further notable species, not identified during the survey, may exist within the vicinity.
Given the extent of the site, the nature of the habitats present and the work proposed these are not considered to represent significant limitations to the findings of this report.
3. Results
Findings are presented below with a brief description of each of the sub - communities identified within the main habitat types and illustrative photos.
Habitat distribution is shown on Map 2 in Appendix 1 along the locations of quadrats and target notes.
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Quadrat data and a species list of the dominant vascular plant species within each habitat type is included in Appendix 2
3.1. Designation
Both the main NVC survey area and the proposed access route lie within the following statutory sites of nature conservation interest:
Tintagle-Marsland-Clovelly Coast SAC This 60km long site comprises of mostly
hard, vertical, strongly maritime coastal cliff with intervening slumped sections. It is designated for the occurrence of the Annex 1 habitats1 Vegetated sea cliffs of the Atlantic and Baltic Coasts, Old sessile oak woods with Ilex and Blechnum in the British Isles and European dry heaths.
Bude Coast SSSI The cliffs within this site which stretches from Furzey Cliff to the
north of Bude to Efford Cliff to the south exhibit a number of important geological features associated with the Bude Formation including Carboniferous sandstone which (unusually in Cornwall) gives rise to the local occurrence of herb rich calcareous grassland species including a number of rare and locally restricted plants.
3.2. Habitat descriptions
Maritime grassland
Compass Point and the promontory behind it including the Storm Tower and the site to which it will be relocated (shown as the NVC survey area on Map 2 ) are dominated by a mixed grassland assemblage, showing declining maritime influence moving inland from the cliff edge. For the most part the area is referable to different sub-communities of MC8 Festuca rubra-Armeria maritima maritime grassland. This community is characterised by a generally closed sward dominated by red fescue (Festuca rubra) with a wide range of associates depending upon the form it takes but typically including species such as thrift (Armeria maritima), plantains (Plantago species), creeping bent (Agrostis stolonifera) and here varying amounts of Yorkshire fog (Holcus lanatus).
MC8 is the most maritime of the grasslands proper found on coastal cliffs in the UK typically occupying a zone above rock-crevice communities on cliffs below and more mesic grassland communities as one moves inland and maritime influence declines.
Immediately to the south of the Storm Tower quadrats 1 and 2 were taken within a dry, disturbed area where thrift is more or less co-dominant with red fescue with very few associates other than occasional – locally frequent buck’s-horn plantain (Plantago coronopus) and ribwort plantain (P. lanceolata), occasional hawk-bit (Leontodon saxatilis) and scattered white clover (Trifolium repens). This area has been mapped as MG8g the Armeria maritima-dominated sub-community which is typical of more maritime exposures where drainage is excessive and there may be some degree of erosion (as here, presumably resulting from footfall) such that thrift gains a competitive advantage with its deep fleshy rootstock.
1 As listed on Annex 1 of the EC Habitats Directive (CEC, 1992) and are therefore recognised as
being habitats of European nature conservation importance
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Photo 1: Q1 disturbed community with abundant thrift assigned as MC8g
To the north along the coast-path where footfall tends to be highest from walkers visiting the tower there is a very short, tight sward still dominated by red fescue but with grass occurrence almost matched by that of buck’s-horn plantain and sea plantain (Plantago maritima). Within the quadrats (Q4, 9 & 10) daisy (Bellis perennis) is the only other constant; ribwort plantain, cat’s-ear (Hypochaeris radicata) and lesser hawk-bit (Leontodon saxatilis) are rare. The abundance of low growing rosettes within this type of sward is classically a response to grazing for which trampling here serves as a proxy. This community has been assigned as the Plantago coronopus sub-community MC8e.
Photo 2: Q4 heavily trampled grassland assigned to MC8e
In contrast to the above beyond the fence, where there is no access, the sward is noticeably more luxuriant with a thick mattress of red fescue excluding all but a few associates such as occasional cushions of thrift and a scattering of bird’s-foot trefoil (Lotus corniculatus). This area was mapped as the species poor MC8a typical sub-community.
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Photo 3: cliff edge near to Q5
Red fescue remains dominant across the bulk of the central part of the promontory (Q3 and Q8) the sward varying in stature and species richness. The occurrence of species characteristic of inland neutral grassland at moderate levels of abundance, most notably Yorkshire fog but also cock’s-foot (Dacylis glomerata) and crested dog’s-tail (Cynosurus cristatus) suggests MC8d the Holcus lanatus sub-community.
Photo 4: Q3 ranker intermediate sward with Yorkshire fog treated as MC8d
This transition toward more mesic grassland is further consolidated moving south toward the fence (Q6 and Q7) with fewer maritime obligates, increased abundance of the grasses above and the addition of species such as common bent (Agrostis capillaris) and bulbous buttercup (Ranunculus bulbosus) as well as increased amounts of clover (Trifolium repens and T.pratense). This area has been mapped as transitional between MC8d and MC9b
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Festuca rubra-Holcus lanatus grassland (the latter a community characteristic of more sheltered cliff tops and lee-slopes).
Photo 5: Q6 transitional grassland to the south mapped as MC8b – MC9d
Within this area the location to which the tower will be re-located (Q12, Q11 an Q13) shows a degree of localised species-richness with the presence of species such as wild thyme (Thymus drucei), vernal squill (Scilla verna) and the notable species tormentil (Potentilla erecta) and devil’s-bit scabious (Succisa pratensis).
Photo 6: Q11 area to which the tower will be re-located (MC8d - MC9b)
The areas of maritime grassland support notable plant species (see below) qualify as the priority habitat2 Maritime cliff and slopes and the Annex 1 habitat Vegetated sea cliffs of the Atlantic and Baltic Coasts for which the SSSI and SAC respectively are designated.
2 As listed on Section 41 of the Natural Environment and Rural Communities (NERC) Act 2006. This
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Without appropriate care and mitigation it is considered that movement of the tower has the capacity to impact on areas of maritime grassland as follows:
Disturbance to / degradation of areas around existing location of tower as required to establish a working area / compound and facilitate dismantling (of tower as well as associated hard-standing / paved surround) including lay down / storage / loading area for transit to new site – size of area required to be confirmed. Potential for ground disturbance and compaction due to machinery and vehicle movements and dust / rubble deposition or release of other pollutants within the area.
Disturbance to / degradation along c.100m x c.2m wide transit route between existing and new site – ground disturbance and compaction due to vehicle movements used to transport stone and other materials.
Habitat loss at the new site to accommodate the footprint of the relocated tower and disturbance to / degradation of the surrounding area as required to establish a working area / compound and facilitate re-construction (of tower as well as any associated hard-standing / paved surround) including lay down / storage area – size of area required to be confirmed. Potential for ground disturbance and compaction due to machinery and vehicle movements and dust / rubble deposition or release of other pollutants within the area.
A precautionary approach should be followed and a methodology developed to minimise potential impacts upon the maritime grassland habitat as discussed in Section 4 below.
Heath
Within the extreme eastern end of the NVC survey area (Q14 and Q15) Western gorse (Ulex gallii) dominates a heathland assemblage with frequent heather (Calluna vulgaris) at low levels of abundance. Associated species are few: toward the edges and within openings in the canopy wild thyme, betony (Stachys officinalis), common dog violet (Viola riviniana) and green-ribbed sedge (Carex binervis) add some diversity and the notable species dodder (Cuscuta epithymum), parasitic on gorse is locally frequent. This community matches the species-poor sub-community of Calluna vulgaris –Ulex gallii heath H8a.
The area of heath supports notable plant species (see below) and qualifies as both the priority habitat Lowland heathland and the Annex 1 habitat European dry heath.
Although this habitat should not be directly impacted by the proposal the tower will be relocated to an area close to the area of heathland. Without appropriate care it is considered that re-construciton has the capacity to impact on areas of heath as follows:
Direct disturbance as a result of vehicle movements, storage of materials etc. resulting in damage to vegetation and ground compaction
Habitat degradation due to dust / rubble deposition or release of other pollutnats within the area
See Section 4 for discussion of precautionary approach to be followed and methodology to be adopted to minimise potential impacts upon this habitat.
legislation requires the Secretary of State to publish a list of species of flora and fauna and habitats considered to be of principal importance for the purpose of conserving biodiversity. It is the duty of Local Authorities to further the conservation of NERC / Section 41 (S41) habitats and species under section 40 of NERC Act and in accordance with the National Planning Policy Framework (NPPF, 2012).
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Semi-improved grassland
The access route follows an established pedestrian access track running roughly east-west along the valley bottom from Church Path to a gate c.40m from the tower.
The track itself is well used up to c.2m wide and supports a short, compacted sward dominated by varying amounts of red fescue and common bent with frequent-locally abundant perennial rye-grass (Lolium perenne), occasional Yorkshire fog and crested dog’s- tail and locally abundant rosette forming species such as ribwort plantain and daisy.
Alongside the access route grassland within the valley bottom and surrounding gentle slopes is varied both physiognomically and in terms of species composition appearing in places rank and rather poor, elsewhere more open and species-rich. Cock’s-foot and Yorkshire fog tend to be abundant throughout, the former dominating locally; red fescue too is abundant, false oat-grass (Arrhenatherum elatius), smooth meadow-grass (Poa trivialis), common couch (Elymus repens), crested dog’s-tail and soft brome (Bromus hordaceous) are all locally frequent. Black knapweed (Centaurea nigra) and bird’s-foot trefoil are frequent often with white and / or red clover (Triflolium repens and / or T. pratense). Restharrow (Ononis repens) is locally frequent on richer south-facing slopes and hogweed (Heracleum sphondylium) becomes frequent within ranker stands with occasional creeping thistle (Cirsium arvense).
This assemblage, although not sampled in detail resembles MG1 Arrhenatherum elatius grassland with probable stands of both the species-poor Festuca rubra sub-community (MG1a) and the richer Centaurea nigra sub-community (MG1e). MG1 is characteristic of
irregularly grazed / cut grassland over circumneutral soils in the British lowlands and is often found at the landward end of maritime grassland successional sequences.
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Photo 7: access track looking east with semi-improved grassland (MG1) either side
Photo 8: as above looking north west
Within a flushed area in the valley bottom (at target note 7) tufted hair-grass (Deschampsia cespitosa) is locally abundant with a suite of poor-fens species including hairy sedge (Carex hirta), common sedge (C. nigra) and glaucous sedge (C. flacca), fleabane (Pulicaria dysenterica) and silverweed (Potentilla anserina). This community appeared fragmented and was not assessed in detail but bears some affinity to MG9 Holcus lanatus – Deschampsi cespitosa grassland.
Within the valley bottom at the eastern extent of the area to the north of the gate leading to Church Path (target notes 11 and 12) there is a community featuring a suite of species associated with calcareous grassland. Whilst red fescue remains more or less dominant the sward is markedly more open and species-rich with locally abundant carices (including glaucous sedge); quaking grass (Briza media), carline thistle (Carlina vulgaris), ladies- bedstraw (Galium verum), betony, devil’s-bit scabious, greater knapweed (Centaurea scabiosa), restharrow, wild thyme and south-marsh orchid (Dactylorhiza praetermissa) are
all locally frequent. There is a further colony of southern marsh orchid at target note 10.
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Although not quantitatively sampled this assemblage bears elements of CG1 Festuca ovina – Carlina vulgaris grassland very unusual in Cornwall and of considerable interest.
Whilst the grassland assemblage along the established track itself is of relatively low
intersest more species rich areas of semi-improved grassland support a number of notable
species (see below) and may qualify as the priority habitat Lowland meadow. Areas
supporting calcareous species may also qualify as Lowland calcareous grassland for which
the SSSI is in part designated.
Although there should be no direct impact to these areas during work a precautionary
approach should be followed to ensure that species rich areas supporting notable species
are protected to prevent degradation associated with vehicle movements and storage of
materials etc. during work. See Section 4 below.
Photo 9: showing area of species-rich calcareous grassland north of access track (TN12)
Photo 10: southern marsh-orchid with quaking grass within species rich grassland at TN12
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Photo 11: looking north toward TN11. Carline thistle, quaking grass and greater knapweed
locally frequent in this area
Scrub
Scrub is a very minor component of the survey area and was not looked at in any detail
during the survey. Several scattered stands have been mapped along the eastern half of the
access roué as shown on Map 2. Bramble (Rubus fruticosus) dominates with locally
abundant common nettle (Urtica dioica), cleavers (Galium aparine) and coarse grasses such
as false oat-grass and cock’s-foot.
This assemblage may offer some habitat for faunal…