Dorset Hedgerow Surveys Final Report
20th December 2010
Prepared by: Annabelle Phillips Dorset FWAG, Government Buildings, Prince of Wales Road. Dorchester DT1 1PY
Telephone: 01305 251742 Fax: 01305 214310 E-Mail: [email protected]
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Contents
Summary 3
1.0 Introduction 4
2.0 Aims and objectives 4
3.0 Raising Awareness 5
4.0 Survey methodology 6 4.1 Identifying hedges and landowners 6 4.2 Field Survey 6 4.3 Recording 7
5.0 Survey results and conclusions 7 5.1 Adjacent land use 7 5.2 Hedgerow structure 7 5.3 Species richness 8 5.4 Species composition 8 5.5 Condition assessment 10 5.6 Management 11 5.7 Hedgerow Trees 11
6.0 Hedgerow management advice 12 6.1 On-site advice 12 6.2 Feedback to Landowners 12
6.0 Contribution to Dorset Biodiversity Strategy 13
7.0 Conclusions 14
Acknowledgements
Appendices Appendix 1- Project Area and Parishes Surveye Appendix 2- Survey Summary From Appendix 3- Survey Feedback for Landowners
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Summary
The Dorset Hedgerow Surveys Project surveyed hedgerows within the parishes of Hammoon, Manston, Hinton St Mary and small areas of Marnhull, Sturminster Newton and Okeford Fitzpaine in North Dorset during 2010 using the Defra hedgerow survey methodology. The project concentrated on hedgerows in an area dominated by arable farming and which had been identified as a ‘hotspot’ for the Hazel Dormouse by the Peoples Trust for Endangered Species.
In total 135 hedges were surveyed using the Defra hedgerow survey methodology, surveying principally for species richness and condition.
61% of surveyed hedges were found to be species rich (containing 5 or more species in a 30 metre stretch). This is above the 42% national average (UK BAP for ancient and/or species-rich hedgerows).
The most dominant species found within the hedgerows were Blackthorn, Hawthorn, Field Maple, Dog Rose, Blackberry, Elder and Hazel.
19% of surveyed hedges are in favourable condition, with most failures (77%) due to basal canopy height.
24% of hedgerows also failed the condition assessment due to the presence of nutrient enrichment indicator species found adjacent to the hedge.
78% of hedges had received some form of management within the past 2 years, most commonly trimming with a flail.
The survey results have been uploaded to the Survey Database on the Hedgelink website. All landowners who had surveys undertaken on their land have received feedback on the findings of the surveys and appropriate hedgerow management advice to enhance the hedges on their land.
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1.0 Introduction
Ancient and/or species-rich hedgerows were identified in the Dorset Biodiversity Strategy under the agricultural theme as a key habitat and of high survey priority. South West England, including Dorset, has a high proportion of species-rich hedges and besides being a BAP habitat in itself, a number of priority BAP species are associated with hedgerows in North Dorset, including the Hazel Dormouse and Brown hairstreak butterfly. Hedgerows are not only of high environmental value but many are also significant in a historical or landscape context. This makes hedgerows of particular conservation importance.
The Dorset Hedgerow Surveys Project collected data on hedge distribution, condition and species diversity within the parishes of Hammoon, Manston, Hinton St Mary and small areas of Marnhull, Sturminster Newton and Okeford Fitzpaine in North Dorset. Surveys were undertaken during 2010 using the Defra survey methodology. The project concentrated on hedgerows in an area dominated by arable farming and which had been identified as a ‘hotspot’ for the Hazel Dormouse by the Peoples Trust for Endangered Species.
The Dorset Hedgerow Surveys Project has been funded by Defra’s Local Hedgerow Survey fund.
2.0 Aims and objectives
The Dorset Hedgerow Surveys Project had three principal aims; to conduct a survey of existing hedgerows, to provide advice to farmers and landowners on appropriate future management and to contribute to the data gathered to other relevant organisations such as the Dorset Environmental Records Centre and The Peoples Trust for Endangered Species Hedgerows for Dormice Project.
Hedgerow survey objectives:
Undertake detailed survey of hedgerows within the parishes Hammoon, Manston, Hinton St Mary and small areas of Marnhull, Sturminster Newton and Okeford Fitzpaine using Defra hedgerow survey methodology.
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Contribute to the Dorset Biodiversity Strategy and UK BAP targets for ancient and species rich hedgerows, which are a priority habitat.
Identify hedges requiring additional management to enhance the habitat available to wildlife or for local landscape character value.
Hedgerow management objectives:
Promote appropriate management and restoration techniques.
Promote grants available for hedgerow management, restoration and planting such as agri-environment schemes.
Awareness objectives:
Provide feedback to farmers and landowners on the key findings from the project.
Raise awareness in the local community about the environmental importance of hedgerows as wildlife corridors and historical features of the landscape, and the benefits of adopting appropriate management techniques.
3.0 Raising Awareness
Awareness of the project and the importance of good hedgerow management was raised by submitting articles to parish magazines and other newsletters. An article about the project was also published in the local FWAG Newsletter.
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4.0 Survey Methodology
The data collected through the Dorset Hedgerow Surveys will contribute towards a national database on hedge condition which is collated by Hedgelink. In order for the data to be comparable with other surveys all surveys have been undertaken using the methodology described in the ‘Hedgerow Survey Handbook’ (Defra, 2007).
4.1 Identifying hedges and landowners
The project area included the parishes of Hammoon, Manston, Hinton St Mary and small areas of Marnhull, Sturminster Newton and Okeford Fitzpaine (see Appendix 1). The Defra methodology for conducting a random survey sample suggests using a hedge density of 9 hedges/km². This was achieved by dividing 1 km² squares on an Ordinance Survey map into 9 x 333 m² blocks. The hedge closest to the centre of each block was then selected for surveying (full details are described in the Defra Hedgerow Survey Handbook).
Landowners were identified using local knowledge and the ‘Nature on the Map’ website (www.natureonthemap.org.uk). Landowners were sent an initial letter explaining the project followed up with a phone call to arrange a suitable survey date. In total 12 landowners had surveys undertaken on their farms. Dorset FWAG has a good relationship with many of the farmers within the project area, so no objection was met towards the project.
4.2 Field survey
The survey method stated in the Defra Hedgerow Survey Handbook 2nd Edition was followed with all of compulsory Part A being completed and the hedgerow management section of optional Part B. All selected hedges were surveyed over a 30m stretch on both sides. Information on hedge length and grid references were obtained from digital maps through a desk based study.
The majority of field work was carried out by a FWAG Farm Conservation Adviser, with support from 2 volunteers during August and September. 135 hedges were surveyed across the 6 parishes.
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4.3 Recording
The survey data has been entered onto the database on the Hedgelink website for collation and analysis. A survey summary form has been completed and can be found in Appendix 2.
5.0 Survey Results
5.1 Adjacent Land Use
Adjacent land use % Arable Land 53 Improved Grassland 47 Woodland 1 Figure 1: Adjacent land use
Within the Project area the most common adjacent land use to the hedges surveyed was arable land, closely followed by improved grassland. This was expected as the surveys were targeted in an area dominated by arable and dairy farming.
5.2 Hedgerow Structure
The full description for each of the structure categories is described in the Defra “Hedgerow Survey Handbook” (Defra, 2007).
84% hedges were classed as shrubby. 2% hedges were classed as a line of trees. 13% hedges were classed as shrubby with a line of trees.
The majority of surveyed hedges have been categorised as ‘shrubby’ which indicates that they have received some form of regular management, most commonly trimming with a flail. However it was noted during the surveys that trimming is not always applied to the whole hedge, with many being sided-up but not trimmed on top.
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5.3 Species Richness
The Defra methodology defines a species rich hedge as one which contains 5 or more native or archaeophyte woody species per 30 m length, not including climbers (other than roses) or brambles.
A total of 23 woody species were found in the 135 surveyed hedges which are listed below in Figure 2.
Of the 135 hedges surveyed 61% were found to be species rich, which is above the 42% national average quoted in the UK BAP for hedgerows.
19% of hedges surveys were found to contain 7 or more species per 30m, which would classify them as important under the Hedgerow Regulations. 12 was the highest number of woody species recorded in a 30m section of hedge, with 5.03/30m being the average number of woody species found in all surveyed hedgerows.
5.4 Species composition
The most common species found within the hedgerows surveyed were Blackthorn, Hawthorn, Field Maple, Dog Rose, Blackberry, Elder and Hazel. Most hedges were dominated by Hawthorn or Blackthorn, with hawthorn being found in 73% of hedgerows and Blackthorn being found in 84%. A full list of all species found and the percentage of hedgerows in which they were found is detailed below in Figure 2.
Common Name Latin Name Percentage of hedges species was recorded
Field Maple Acer campestre 56%
Sycamore Acer pseudoplatanus 1%
Hazel Corylus avellana 36%
Hawthorn Crataegus monogyna 73%
Spindle Euonymus europaeus 1%
Ash Fraxinus excelsior 25%
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Ivy Hedera helix 6%
Privet Ligustrum vulgare 2%
Crab Apple Malus sylvestris 1%
Scots Pine Pinus sylvestris 1%
Blackthorn / sloe Prunus spinosa 84%
Pendunculate oak / Quercus robur 10% English oak
Oak Quercus spp. 7%
Purging buckthorn Rhamnus cathartica 13%
Dog rose Rosa canina agg. 43%
Blackberry Rubus fruticosus 43%
Willow Salix spp. 14%
Elder Sambucus nigra 41%
Lime Tilia x vulgaris 1%
Wych elm Ulmus glabra 1%
English elm Ulmus procera 41%
Guelder-rose Viburnum opulus 1%
Leylandii x Cupressocyparis leylandii 1%
Figure 2: Woody Species recorded throughout the Dorset Hedgerow Surveys (per 30m length.
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5.5 Condition assessment
The “Hedgerow Survey Handbook” (Defra, 2007) details 5 criteria that have to be met in order to classify a hedgerow as in favourable condition. These are:
Undisturbed ground: at least 2m of undisturbed ground from the hedge centre line. Perennial herbaceous vegetation cover: at least1m of herbaceous vegetation cover from the hedge centre line. Nutrient enrichment: less than 20% combined cover of nettles, cleavers and docks. Recently introduced non native species: A maximum of 10% non- native herbaceous species and 10% non-native woody species. Dimensions: at least 1m high, at least 1.5m wide and with a cross- sectional area of at least 3m². Gaps: less than 10% gaps and no gaps greater than 5m. Basal canopy height: base of canopy must be less than 0.5m above ground.
From the 135 hedges surveyed only 19% were found to be in favourable condition. The greatest cause of hedges failing the condition assessments is due to basal canopy height being above 0.5m, with 77% of hedgerows failing on this assessment.
Nutrient enrichment is the second most common cause of failure, with 24% of hedges failing on this criteria. Nutrient enrichment is an optional part of the condition assessment and a number of other surveys have omitted it from their results. For the purpose of this report the decision was taken to include this element as it gives an indication of the floral diversity of the hedge bottom and also an insight into the management of surrounding land. Much of the farmland within the project area is dominated by arable and dairy farming which often have high fertiliser inputs. This can account for the high levels of indicator species of nutrient enrichment within the ground flora.
The full list of all failures is detailed below in Figure 3.
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% Failures Undisturbed ground 1% Herbaceous vegetation 5% cover Nutrient enrichment 24% indicators Recently introduced 0% species Dimensions 7% Gaps 12% Basal canopy height 77% Figure 3: Percentage of hedges which failed against each condition assessment.
5.6 Management
The survey identified whether hedge management had occurred within the last 0- 2 years, 2- 10 years or >10 years. 78% of hedges surveyed had been flailed within the past 2 years and many of the farms surveyed were in an agri-environment scheme, which often includes hedge options such as biannual trimming under Entry Level Stewardship.
No hedges surveyed showed evidence of having been recently laid and it appears there is a lack of this type of management within the project area.
5.7 Hedgerow Trees
The most common species of hedgerow tree recorded was Pedunculate Oak (28%) and Oak Sp. (28%), with Ash (23%), Field Maple (10%) and Willow (7%) trees also being recorded. 40% of isolated hedgerow trees recorded were found to have a diameter at breast height of between 20- 60cm, 28% with a diameter of 60-100cm and 22% with a diameter above 100cm.
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6.0 Hedgerow Management Advice
Feedback given to farmers and landowners in the project area not only provided information on the survey results but also gave management advice for the hedges on their holding.
6.1 On-site advice
During the field surveys surveyors often met the landowners and discussed their current hedgerow management regime as well as advising on the importance of their hedgerows and how best to improve hedgerow condition across the farm.
6.2 Feedback to Landowners
A report was also sent to each landowner who had hedges surveyed on their land detailing what was found during the surveys and how best to manage their hedgerows to benefit wildlife and the environment. Details on sources of funding for hedgerow restoration and planting were also included in this report. An example for this feedback report can be found in Appendix 3.
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7.0 Contribution to the Dorset Biodiversity Strategy for ancient and/or species rich hedgerows
The Dorset Hedgerow Surveys Project has contributed to priorities identified through the Dorset Biodiversity Strategy which indicated hedgerows to be of ‘high’ survey priority. These included:
Raising awareness of importance of hedges and targeting for grant aid.
Targeting grants for planting to sites which link or reinforce existing hedges/ create corridors between other features/ help control run-off, using native species.
Using results of hedgerow surveys to inform hedgerow policies and grants in Dorset, and more widely.
Using results of hedgerow surveys to produce Dorset-specific guidance on habitat quality.
Raising awareness of management issues. Inappropriate management, including too frequent or ill-timed cutting, prevents hedges from producing fruits and berries that are a food source for many species. The type of cutting can also damage hedges.
Increasing the knowledge of the Dorset resource.
(Dorset Biodiversity Strategy, 2003)
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8.0 Conclusions
High proportion of species-rich hedges. It was known before the survey that Dorset held a high proportion of species-rich hedgerows, with 61% being found during this survey project. This figure is above the 42% national average as quoted in the United Kingdom BAP for Hedgerows.
The majority of hedges are in unfavourable condition. Only 19% of the hedges surveyed were in favourable condition. The height of the base of canopy was the most significant cause of hedges failing to be in favourable condition. It was also noted that none of the hedges surveyed had been recently laid and it is likely this is one of the main reasons for a high basal canopy.
Low uptake of good hedge trimming practice. Changes to flail techniques would have a considerable affect on reducing the number of hedges failing on size, particularly by increasing the height progressively over a number of years. By gradually increasing the height at which the hedge is trimmed it will also help to maintain a dense, healthy hedge. Encouraging and advising farmers and landowners to choose hedge options such as biannual trimming in an ELS application may be one method of achieving this.
Many hedges suffer from nutrient enrichment at their base. Despite introduction of Cross Compliance buffer strips, 24% of the hedgerows surveyed suffered from nutrient enrichment indicated by aggressive weed species, such as Nettles, Docks and Cleavers, which can swamp native flora. This is likely to be due to the build up of nutrients over several decades, resulting in a fertility level that will take many years to decline. Provision of advice to farmers and landowners on appropriate field edge management would be beneficial.
Gaps within the hedgerows. 12% of hedges surveyed had gaps within them. This is of particular importance as the area is known to be a ‘hotspot’ for the Hazel Dormouse which lives within hedgerows as well as using them as dispersal corridors. Gaps within hedgerows are of
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particular significance were Dormice occur as they are reluctant to cross gaps. The network of hedgerows could be improved by gapping up the existing hedgerows to enhance these wildlife corridors.
Historic and landscape value of hedgerows. The historic and landscape value of hedges is not assessed as part of the standard Defra survey methodology. It may be beneficial to include such assessments in future surveys.
Future Hedgerow Management. Advice has been given to farmers and landowners on good hedgerow management. It was noted that no hedges surveyed had recently been laid. As a result FWAG are running a hedge laying workshop near the project area in February 2011 to encourage the use of this traditional management technique. Sympathetic management and restoration of hedgerows will safeguard and enhance the valuable hedgerow habitat for the future.
Acknowledgements
The Dorset Hedgerow Surveys Project was funded by Defra’s Local Hedgerow Survey fund. With thanks to the farmers and landowners who granted permission for us to survey their hedges and to the volunteers, Catherine Garman and Adam Kennedy, who assisted with the hedgerow surveying and data input. The Peoples Trust for Endangered Species Hedgerow for Dormice Project also provided their Dormouse ‘hotspots’ GIS layer.
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Appendix 1- Project Area and Parishes
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Survey Summary Form Steering Group for the UK Biodiversity Action Plan for Hedgerows
1. Survey title 2. Year(s) of survey Dorset Hedgerow Surveys 2010 3. Surveyed area
North Dorset- Parishes of Hammoon, Hinton St Mary, Manston and (Place) 1535 ha small areas of Sturminster Newton, Marnhull and Okeford Fitzpaine. 4. Report title, authors, publisher and where it can be obtained 'Dorset Hedgerow Survey Final Report' written by Annabelle Phillips of Dorset FWAG. Available from Dorset FWAG and the Hedgelink website.
5. Lead body Contact name Address Annabelle Phillips Government Buildings
Telephone number (incl. national dialling code) Prince of Wales Road 01305 251742 Dorchester
E-mail Dorset
[email protected] Postcode DT1 1PY 6. Key partners Funded by Defra
7. Survey cost (only include actual expenditure) Total £ 6700 Defra grant £ 5000
8. Overview of objectives and results (100 words max)
FC 2 (02/10) 1 The Dorset Hedgerow Surveys Project surveyed hedgerows in North Dorset during 2010 using the Defra hedgerow survey methodology. The project concentrated on hedgerows in an area dominated by arable farming which had been identified as a ‘hotspot’ for the Hazel Dormouse by the Peoples Trust for Endangered Species.
In total 135 hedges were surveyed, with 61% of hedges found to be species rich (containing 5 or more species in a 30m stretch). This is above the 42% national average (UK BAP for ancient and/or species-rich hedgerows).
19% of surveyed hedges are in favourable condition, with most failures (77%) due to basal canopy height.
9. Survey method Hedgerow Survey Handbook 2nd Edition (without modification) ......
Other (specify)......
10. Survey type Full census ...... Random or near-random sample ...... Non-random sample......
11. Survey level (Refers to different parts of the Field Survey Form – tick all which have been used) Core Assessments (Part A) ...... Associated features/Hedgerow/Margin . management (Part B) ......
Ground flora (Part B)...... Veteran tree features (Part B) ......
12. Hedgerow length & Numbers Length (km) Number Total for surveyed hedgerows 30.26 135
Total in survey area (if different)
13. Main hedgerow types (give rough proportions for each type) Shrubby Shrubby Recently 84 % Lines of trees 2 % 13 % 0 % Hedgerows with lines of planted
Trimmed and Intensively Hedgebanks % 47 % 6 % Untrimmed 21 % dense managed
Tall and Untrimmed with Recently laid 19 % 7 % % leggy outgrowths or coppiced
14. Adjacent land use Arable 53 % Grass 47 % Woodland 1 % Built %
Other
(specify)
15. Average number of connections per hedgerow 3.3
FC 2 (02/10) 2
16. Proportion of species-rich hedgerows 61 % (% of hedgerows with 5 or more native woody spp/30m or 4 or more in N&E England or Scotland)
17.a. Proportion of hedgerows made up of >80% native woody species 98 % (include archaeophytes and sycamore)
17.b. Proportion of hedgerows made up of >80% native woody species 97 % (not including archaeophytes and sycamore)
18. Condition Assessment: (Give % in favourable condition in each box) 1. Dimensions 93 2. Gaps along length 88
3. Basal canopy height 23 4. Undisturbed ground 99
5. Herbaceous vegetation cover 95 6. Recently-introduced species 100
7. Passed all above six criteria 19
8. Nettle, dock and cleaver cover <20% (Nutrient enrichment) 76
19a. Isolated hedgegrow trees % in size classes (cm DBH) (only include large species, e.g. oak, ash, beech and sycamore) <5cm 2 % 5-20 2 % 20-60 40 % 60-100 28 % >100cm 22 %
19b. Number of trees >100cm DBH and other veterans per 1 km of hedgegrow surveyed 0.4
20. Total number of isolated hedgerow trees in survey area 60
21. Data storage Microsoft Access Database ...... GIS......
Other (specify)...... Hedgelink/Fera web-based database......
22. Data held by: Local Records Centre/ Biodiversity Action Biological Records Centre ...... Reporting System......
Other (please specify) ......
23. Volunteers Number of individuals...... 2 Number of volunteer days ...... 10
24. Changes noted from previous surveys (e.g. extent, condition, woody species diversity, new planting, management, connections) (optional)
FC 2 (02/10) 3 N/A
Signature Date 20/12/2010
Name in BLOCK LETTERS Annabelle Phillips Contact telephone number 01305 251742
FC 2 (02/10) 4