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Scottish Natural Heritage

Commissioned Report No. 367

Species audit and appropriate

management of conservation

verges in Orkney


COMMISSIONED REPORT

Commissioned Report No. 367

Species audit and appropriate management of

conservation verges in Orkney

For further information on this report please contact:

Tim Dean

Scottish Natural Heritage

54-56 Junction Road

Kirkwall

Orkney

KW15 1AW

Telephone: 01856 875302

E-mail: Tim.Dean@snh.gov.uk

This report should be quoted as:

Crossley, J. 2010. Species audit and appropriate management of conservation verges in

Orkney. Scottish Natural Heritage Commissioned Report No.367.

This report, or any part of it, should not be reproduced without the permission of Scottish Natural Heritage. This

permission will not be withheld unreasonably. The views expressed by the author(s) of this report should not be

taken as the views and policies of Scottish Natural Heritage.

© Scottish Natural Heritage 2010.

i


COMMISSIONED REPORT

Summary

Species audit and appropriate management of

conservation verges in Orkney

Commissioned Report No. 367 (iBids No. 1440)

Contractor: John Crossley

Year of publication: 2010

Background

Orkney’s road verges support a wide range of habitat types, many regarded as of great

wildlife interest. The best of them, dubbed ‘Conservation Verges’, have in recent years

received no management and there are now fears that they are losing some botanical

diversity and interest. This report details the methods and results of a survey of these

verges carried out in July and August 2008 and makes recommendations for their future

management.

Main findings

A total of 66 miles of Conservation Verges was surveyed. 33 miles (50%) of this length was

found to support very or moderately herb-rich forms of Unimproved neutral grassland,

corresponding to the UKBAP Priority habitat Lowland Meadow. 27 miles (40%) was found

to support Semi-improved neutral grassland or a coarse and relatively species-poor form

of Unimproved neutral grassland. A further 12 Phase 1 habitats accounted for the

remaining 10%. Of particular interest among these, for species-rich vegetation and

uncommon plants, are Unimproved calcareous grassland, Coastal heath and grassland,

and Open dune. These also correspond to some UKBAP Priority habitats.

Individual verges were usually of mixed quality, i.e. they could be seen as linear mosaics of

habitat types. There were a small number of longer sections of verge with vegetation of high

conservation value.

Plants recorded that are unusual in a national or local context included Scottish primrose

(Primula scotica), field gentian (Gentianella campestris), hybrid St John’s-wort (Hypericum

desetangsii), two species of fragrant orchid (Gymnadenia borealis and Gymnadenia

densiflora), oysterplant (Mertensia maritima) and holy grass (Hierochloe odorata) .

Much of the vegetation appeared to be increasingly dominated by coarser species of grass

or other plants. This is put down to the lack of any mowing. In order to counteract this, it is

recommended that a programme of managed mowing be carried out. The recommendation

is supported in this report by an ecological explanation of the responses of grassland and

other habitats to mowing or the absence of it.

Recommendations for future management chiefly comprise:

1. annual mowing of most of the Conservation Verges;

2. mowing less often, or avoiding mowing altogether, exceptional vegetation that would

not benefit or would be harmed: this chiefly comprises naturally very short, herb-rich

grassland; dwarf shrub; and dune grassland;

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3. twice-annual mowing of some of the most overgrown Conservation Verges.

The recommendations may be implemented by a change in management that will apply to

all Conservation Verges except those supporting vegetation of exceptional quality and the

most overgrown ones. Management other than the norm may be implemented in two ways:

1. by specific management instructions for some longer and more distinct sections,

(identified in this report); and

2. more generally, and applying to verges of more mixed quality, by instructions to mower

operators as to how to recognise vegetation that should be treated differently.

However, annual mowing is an imperfect management solution, because cut plant material

has a smothering effect on the vegetation on which it lies, particularly of course where the

vegetation has become rank. The effect is greater on more sensitive and desirable plant

species. Therefore while mowing is better than no mowing for most grassland, removal of

cuttings afterwards is much better. Removal also has the great longer-term benefit of

reducing soil nutrient levels and with them the vigour of coarse and less desirable species. It

is recognised that the cost of removing cuttings from all Conservation Verges is unlikely to

be acceptable, but it is recommended that it be carried out on selected Conservation Verges

as a pilot project.

For further information on this project contact:

Tim Dean, Scottish Natural Heritage, 54-56 Junction Road, Kirkwall, Orkney, KW15 1AW

Tel: 01856 875302

For further information on the SNH Research & Technical Support Programme contact:

DSU (Policy & Advice Directorate), Scottish Natural Heritage, Great Glen House, Inverness, IV3 8NW.

Tel: 01463 725000 or pads@snh.gov.uk

iii


1. INTRODUCTION ................................................................................................................ 1

2. AIM AND OBJECTIVES..................................................................................................... 1

3. METHODS .......................................................................................................................... 1

3.1 Survey methods and reporting...................................................................................... 1

3.2 Habitat classifications ................................................................................................... 2

3.2.1 Phase 1 .................................................................................................................. 2

3.2.2 UK Biodiversity Action Plan Priority Habitats ......................................................... 5

4. RESULTS ........................................................................................................................... 7

4.1 Vegetation and habitats ................................................................................................ 7

4.2 Less common species .................................................................................................. 8

4.3 Quality of vegetation ..................................................................................................... 8

4.4 Outstanding verges....................................................................................................... 9

4.5 Poorer verges ...............................................................................................................9

5. DISCUSSION and RECOMMENDATIONS...................................................................... 10

5.1 General principles and rationale ................................................................................. 10

5.2 Recommendations ...................................................................................................... 11

5.3 Further suggestions .................................................................................................... 11

6. REFERENCES ................................................................................................................. 13

Appendix 1 - Verges data ................................................................................................. 14

Appendix 2 Sample quadrat data for main vegetation types..................................... 22

iv


Acknowledgements

In carrying out this contract I have received excellent support from Tim Dean, the SNH

nominated officer. I had a useful consultation with him before writing up the results and he

has made several suggestions for improving the clarity of the final report.

v


1. INTRODUCTION

Orkney has c.1750 km of roadside verge, amounting to at least 525 ha owned or managed

by Orkney Islands Council. Roadside verges are included as a locally important habitat in

the Orkney Local Biodiversity Action Plan (LBAP) (Orkney Biodiversity Steering Group,

2002). The verges include a wide range of habitat types, many regarded as of great wildlife

interest. Survey work within the last twenty years has highlighted the ‘best’ of these verges

and they have subsequently been designated as Conservation Verges. By necessity the

initial verge survey took a very broad approach to identification and simply graded verges

into five categories with those of Definite Conservation Value at the top of the list and those

of Little Conservation Value at the bottom with three grades in between. Most of those

verges that were deemed of Definite Conservation Value became “Conservation Verges”.

While now protected from indiscriminate cutting, these verges are not fully reaping the

rewards of their status. Those verges that are deemed Conservation Verges receive no

management whatsoever. Consequently, some of these verges are losing their botanical

diversity.

A further issue is whether some of the verges can be considered UK Biodiversity Action Plan

(UKBAP) Priority Habitats, in particular ‘Lowland Meadow’, as seems likely. If this is the

case, their importance is increased and achievement of favourable condition can contribute

to local and UK Action Plan objectives.

2. AIM AND OBJECTIVES

The main aim of this work is provide information that will inform management to conserve

and enhance the wildlife value of Orkney’s Conservation verges.

The objectives have been to:

1. Carry out a Phase 1 habitat survey, as described in the Handbook for Phase 1

Survey (JNCC, 1993), identify species of particular interest and further assess and

evaluate the quality of Conservation verges;

2. provide recommendations for management.

3. METHODS

3.1 Survey methods and reporting

A list of all Conservation Verges and a map depicting them was provided with the contract.

A preliminary visit to discuss methods, outcomes and any constraints was made to some

road verges on 6 June, with the SNH nominated officer and Orkney Islands Council staff.

Subsequently all the Conservation Verges were walked between 10 July and 7 August. The

first day was spent examining and recording vegetation in detail in order to understand the

range of vegetation types present and usefully classify them. Further recording was carried

out at intervals throughout the survey.

A standard form was used for reporting on each verge. The information recorded comprised

a verge reference, date, Phase 1 category/sub-category, target notes and tentative

recommendations for management (this last to be later revised).

The presence of Phase 1 habitats on each Conservation Verge was approximately

quantified on a scale of 1 – 10, 10 being 100% cover.

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The contract specification included a requirement for a simple ‘species audit’ for each

Conservation Verge as well as Phase 1 classification, i.e. a short list of representative

species. This would provide a necessary further level of detail below the rather broad Phase

1 category. However, it soon became clear that variation in the vegetation conformed to a

consistent pattern and it was thought this would be better represented by a set of projectspecific

categories. The ones used are the Phase 1 categories, and in some cases subcategories

of them, but refined to the particular form in which they were found to occur on

the Orkney road verges. Descriptions are given in Table 1. Target notes are then used to

describe the approximate distribution of the habitats over the length of the Conservation

Verge, and to provide other detail e.g. unusual habitat features or less common species

present.

Evaluation of habitats has been mainly in terms of the UKBAP. Correspondence between

the Phase 1 categories and sub-categories used and UKBAP Priority habitats, adapted from

Jackson (2000) is given in Table 2, and further comment has been made on the local

context.

3.2 Habitat classifications

3.2.1 Phase 1

As noted above, the vegetation found conforms to Phase 1 habitat categories but is locally

distinctive. Descriptions of these habitats given in Table 1 differ in some respects from the

standard ones designed to apply to the UK as a whole. This is partly due to the specific

environment of the road verges (likely to be affected by the application of salt to the roads

and leaching of the road material itself), and partly to the local climatic conditions in Orkney

(especially, comparing northern with southern forms of the same broad habitat type it is

common in the north to find more species associated with cool, damp conditions and less

with warm, dry ones).

One Phase 1 category, Unimproved neutral grassland, has been sub-divided for the

purpose of this survey. This was the commonest type of habitat found, but included an

obvious variety of grassland, from short and herb-rich to coarse and grass-dominated. These

differences are relevant to recommendations for management.

2


Table 1: Description of Phase 1 categories and sub-categories used

Phase 1 Habitat Description

Unimproved

Neutral

Grassland

Semi-improved

Neutral

Grassland

Variable, has mixed grass species including those with finer leaves

especially red fescue (Festuca rubra), sweet vernal-grass

(Anthoxanthum odoratum) and bents (Agrostis sp) usually a little

Yorkshire fog (Holcus lanatus), and often some coarser species,

especially cock’s-foot (Dactylis glomerata) or false oat-grass

(Arrhenatherum elatius), which can become more prominent where

grassland is unmanaged. Therefore can be short (20 cm) or relatively

tall and coarse (70 cm). Usually has crested dog’s-tail grass

(Cynosurus cristatus) where soil is well drained, but often not where it is

wetter.

Has little if any rye-grass (Lolium perenne) or timothy (Phleum

pratense), and is not dominated by cock’s-foot (Dactylis glomerata).

White clover (Trifolium repens) is not abundant. Has few if any coarse

weeds characteristic of nutrient-rich soil, especially docks (Rumex sp)

and creeping thistle (Cirsium arvense).

Has characteristic dicotyledons frequent or abundant. These include

red clover (Trifolium pratense), bird’s-foot trefoil (Lotus corniculatus)

and yellow rattle (Rhinanthus minor), as well as an abundance of others

such as ribwort plantain (Plantago lanceolata) that often occur in more

improved grassland but are less plentiful there. Sea plantain (Plantago

maritima) can be locally frequent. Usually has some sedges, especially

glaucous (Carex flacca) and carnation (Carex panicea) sedges.

May be species-rich (30 species/4m 2 ) or less so (20 species/4m 2 ).

For the purpose of this survey Unimproved Neutral Grassland is divided

into three sub-habitats:

1. Herb-rich, damp

No coarse grasses. Little if any Yorkshire fog (Holcus lanatus). Sedges

are very common. Other herbs include - as well as red clover (Trifolium

pratense), bird’s-foot trefoil (Lotus corniculatus) and yellow rattle

(Rhinanthus minor) - devil’s-bit scabious (Succisa pratensis), tormentil

(Potentilla erecta), eyebright (Euphrasia agg), self-heal (Prunella

vulgaris), northern marsh orchid (Dactylorhiza purpurella), primrose

(Primuls vulgaris), field/many-headed woodrush (Luzula campestris),

marsh (Equisetum palustre) and field horsetail (Equisetum arvense).

2. Standard

Similar in appearance to the herb-rich type, but more grass-dominated

and with fewer species of other herbs.

3. Coarse, tall

Obviously taller vegetation including false oat-grass (Arrhenatherum

elatius) and/or cock’s-foot (Dactylus glomerata) but still including much

red fescue (Festuca rubra)and other characteristic grasses. Still has red

clover (Trifolium pratense) and bird’s-foot trefoil (Lotus corniculatus)

and often some sedges. Damper stands have some meadowsweet

(Filipendula ulmaria)(but see Marsh/marshy grassland).

Similar in general appearance to the ‘coarse, tall’ form of Unimproved

Neutral Grassland, but more cock’s-foot (Dactylis glomerata), some

rye-grass (Lolium perenne), white clover (Trifolium repens), often much

hogweed (Heracleum sphondylium), and sometimes weeds including

docks. Still has finer grasses, especially red fescue (Festuca rubra),

and a scattering of the dicotyledons associated with Unimproved

Neutral Grassland, especially red clover (Trifolium pratense) which is

often frequent. Damper stands have some meadowsweet (Filipendula

ulmaria) (but see Marsh/marshy grassland).

3


Unimproved

Calcareous

Grassland

Marsh/marshy

Grassland

Tall Herb and

Fern – Tall

ruderal

Tall Herb and

Fern – Nonruderal

Dry Dwarf Shrub

Heath – basic

Dry Dwarf Shrub

Heath – acid

Dry Heath/Acid

Grassland

Mosaic

Wet Heath/Acid

Grassland

Mosaic

Coastal

Grassland

Coastal

Heathland

Open dune:

yellow dune

A damp form of calcareous grassland that may or may not include

thyme (Thymus polytrichus), the usual key indicator for this type of

grassland. Short, exceedingly species-rich (c40 species/4m 2 ) grassland

with abundant sedges, especially glaucous (Carex flacca) and

carnation (Carex panicea) sedges.

In the absence of thyme (Thymus polytrichus) a good representation of

certain herbs and some mosses distinguish this grassland from the

‘herb-rich’ form of Unimproved Neutral Grassland. These herbs include

purging flax (Linum catharticum), lesser club-moss (Selaginella

selaginoides), lady’s mantle (the diminutive Alchemilla filicaulis not the

coarser common species) and flea sedge (Carex pulicaris).

Vegetation with a high proportion of rushes (Juncus sp) and/or

meadowsweet (Filipendula ulmaria).

Note that almost all vegetation classed as Marsh/marshy grassland is

distinguished only by a high cover of meadowsweet (Filipendula

ulmaria) and not by other wetland plants. Such vegetation may be seen

in ecological terms as a damp form of neutral grassland (as it is in

NVC) and therefore at the dry end of Marsh/marshy Grassland. Similar

stands with meadowsweet (Filipendula ulmaria) occurring patchily at

less than 25% overall cover is classed as Neutral Grassland.

Rose-bay willowherb (Chamerion angustifolium) dominant

Greater woodrush (Luzula sylvatica) dominant

Herb-rich heath with heather (Calluna vulgaris) and crowberry

(Empetrum nigrum). Herbs similar to Unimproved Calcareous

Grassland.

At some sites, plants characteristic of Coastal Heathland (see below)

were common, though the coast was not close by. Phase 1 convention

requires that only heathland by the sea is defined as Coastal.

Heath with heather (Calluna vulgaris) and crowberry (Empetrum

nigrum), lacking richness of herbs, with no sphagnum and little if any

deer-grass Trichophorum cespitosum), purple moor-grass (Molinia

caerulea) or Common Cotton-grass (Eriophorum angustifolium).

Dry heath and acid grassland mixed. Dry heath with heather (Calluna

vulgaris), bell heather (Erica cinerea) and crowberry (Empetrum

nigrum). Dry Acid Grassland with tormentil (Potentilla erecta), heath

bedstraw (Galium saxatile), fine grasses and sedges (Carex sp).

Wet heath and acid grassland mixed. Wet heath with heather (Calluna

vulgaris), cross-leaved heath (Erica tetralix) and crowberry (Empetrum

nigrum), with a little sphagnum and some deer-grass (Trichophorum

cespitosum) and/or purple moor-grass (Molinia caerulea) and/or

Common Cotton-grass (Eriophorum angustifolium). Wet Acid Grassland

with heath rush (Juncus squarrosus), mat-grass (Nardus stricta),

Common Cotton-grass (Eriophorum angustifolium).

Grassland by the sea, with abundant sedges (Carex sp) and sea

plantain (Plantago maritima), and occasional sea pink (Armeria

maritima) and spring squill (Scilla verna).

Herb-rich heathland by the sea, with dwarf shrubs very short and not

dominant. Sea plantain (Plantago maritima) is frequent or abundant.

Partially stabilised sand dune with marram grass (Ammophila arenaria)

4


Dune Grassland

Grassland on coastal sand, including:

short, red fescue (Festuca rubra) grassland with herbs including

lady’s-bedstraw (Galium verum), bird’s-foot trefoil (Lotus

corniculatus), field woodrush (Luzula campestris), sand sedge

(Carex arenaria), eyebright (Euphrasia agg); and

coarser grassland with red fescue (Festuca rubra), Yorkshire fog

(Holcus mollis) cock’s-foot (Dactylis glomerata)and couch grass

(Elytrigia repens), with fewer of the above herbs.

Some sample quadrat data for the main vegetation types is given in Appendix 2.

3.2.2 UK Biodiversity Action Plan Priority Habitats

Note that the correspondence between Phase 1 habitats and UKBAP Priority Habitats given

here again relates to the specific context of this survey.

Table 2: Table of correspondence between BAP Priority Habitats and Phase 1 categories

and sub-categories

UKBAP Priority Habitat

Lowland Meadow

Lowland Meadow is defined by

National Vegetation (NVC)

communities, the relevant one

here being MG5. The MG1

grassland community,

characterised by the coarse

grasses false oat-grass

(Arrhenatherum elatius) and/or

cock’s-foot (Dactylis glomerata)

is not included in Lowland

Meadow

N/A

Lowland Calcareous

Grassland

N/A

N/A

Upland Heathland

Maritime Cliff and Slope

Phase 1 interpretation

Parts of the Phase 1 Unimproved neutral grassland

described are MG5 and thus Lowland Meadow. These

are the ‘herb-rich’ sub-habitat (1) and the ‘standard’ subhabitat

(2). The ‘poorer’ sub-habitat (3) is excluded:

much of it is MG1, while the remainder being relatively

species-poor is transitional to semi-improved grassland

and not of sufficient quality or conservation importance

to merit inclusion in Lowland Meadow. However, as

explained later in this report, this ‘poorer’ sub-habitat as

whole, may be enhanced and with appropriate

management become Lowland Meadow.

Semi-improved Neutral Grassland

Unimproved calcareous grassland.

No interpretation needed – Lowland Calcareous

Grassland is a form of Unimproved calcareous grassland

Marsh/marshy Grassland.

As explained later in this report, some Phase 1 Marshy

Grassland may with appropriate management become

MG5 and thus Lowland Meadow.

Tall Herb and Fern

Dry dwarf shrub heath – basic.

Dry dwarf shrub heath – basic is a component of Upland

Heathland.

Dry dwarf shrub heath – acid.

Dry dwarf shrub heath – acid is a component of Upland

Heathland.

Heath/acid grassland mosaic: the mosaics found in

this survey were generally herb-rich in character rather

than a ‘run-down’ form of heathland, and as such can be

considered part of the UK Priority habitat.

Coastal grassland

Coastal grassland is a component of Maritime Cliff and

5


Maritime Cliff and Slope

Coastal Sand Dunes

Slope

Coastal heathland

Coastal heathland is a component of Maritime Cliff and

Slope

Dune grassland

Dune grassland is a component of Coastal Sand Dunes

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4. RESULTS

4.1 Vegetation and habitats

The full survey data for all verges is contained in the tables in Appendix 1.

The quantity and share of cover of each of the habitats is summarised in Table 3.

Table 3. Quantity and share of cover of habitats

Phase 1 Habitat Length

miles*

%* UKBAP

Priority

Habitat

Unimproved 44.7 65.5

neutral

grassland, of

which

1. Herb-rich 13.3 19.5

2. Standard 20.4 29.9

3. Poorer 11.0 16.1

Semi-improved 15.8 23.1

neutral

grassland

Unimproved

calcareous

grassland

Marsh/marshy

grassland

Tall herb and

fern – nonruderal

Tall herb and

fern – tall ruderal

Dry dwarf shrub

heath – basic

Dry dwarf shrub

heath – acid

Dry heath/acid

grassland

mosaic

Wet heath/acid

grassland

mosaic

Coastal

grassland

Coastal

heathland

Open dune:

yellow dune

Lowland

Meadow

2.1 3.1 Lowland

Calcareous

Grassland

2.9 4.2

0.2 0.3

0.2 0.3

0.3 0.4

0.1 0.1

0.1 0.1

0.1 0.1

0.6 0.9

0.1 0.1

0.4 0.6

Dune grassland 0.6 0.9

* figures rounded to one decimal point.

Upland

Heathland

Maritime Cliff

and Slope

Coastal Sand

Dunes

Length*

Miles

%*

33.7 49.4

2.1 3.0

0.6 1.0

0.7 1.0

1.0 1.5

7


4.2 Less common species

The following records are especially noteworthy:

1. Scottish primrose Primula scotica (Nationally Scarce), c.200 east of the Yesnaby parking

area (including one plant growing through the tarmac);

2. Field gentian Gentianella campestris (RDB ‘Vulnerable’), at the start of the Roundadee

road (off the Yesnaby road);

3. Hybrid St John’s-wort Hypericum desetangsii at Glims Moss near Dounby. A new County

record, though for a plant common elsewhere in Britain. An apparently thriving group of

plants, seeding into peaty soil disturbed by ditch maintenance;

4. Fragrant orchid Gymnadenia borealis (locally uncommon), at Olad brae viewpoint, South

Ronaldsay;

5. Fragrant orchid Gymnadenia densiflora (locally uncommon), along the Bigswell road,

Stenness, c.200m past the Anderswick road end;

6. Oysterplant Mertensia maritima (RDB ‘Near Threatened’), on the 4 th Barrier;

7. Holy grass Hierochloe odorata (Nationally Rare), almost opposite the Ring of Brodgar.

The occurrence of the above species, with the exception of the St John’s-wort, is restricted

to habitats that are not or are only slightly modified by human activity (most importantly, soil

nutrient enrichment). Scarcely less noteworthy are some other species that are less rare

than the above but whose distribution is similarly restricted to unmodified and scarce

habitats. These include common twayblade Listera ovata, purging flax Linum catharticum,

wild thyme Thymus polytrichus, Limestone bedstraw Galium sterneri, ox-eye daisy

Leucanthemum vulgare, grass-of-Parnassus Parnassia palustris and Alchemilla filicaulis.

Of special value also are native willows. They are unusual on verges, but there are some

along the Bigswell road and the Waulkmill road.

4.3 Quality of vegetation

The ‘herb-rich’ and ‘standard’ types of Unimproved neutral grassland, and the

Unimproved calcareous grassland, are of great conservation value. Unimproved neutral

grassland is rare nationally and in Orkney because it exists in lowland situations and on

soils that are very favourable for enclosure and intensive agriculture. Very little has escaped

that process. What survives is mainly in fragments, especially along track and roadsides,

much more rarely in extensively managed enclosures. The occurrence of Unimproved

calcareous grassland (upland or lowland) is restricted nationally to areas with calcareous

rock and has also been much reduced by agricultural improvement. In Orkney, such rocks

are uncommon and the climate tends to counter-act the raised calcium (and/or other base

e.g. magnesium) level they induce, so this type of grassland occurs more rarely than

Unimproved neutral grassland.

It is probable that salt used on the roads and/or the road material itself contains base

minerals that modify edaphic conditions and thereby contribute to the occurrence or spread

of plants typical of Unimproved neutral grassland and Unimproved calcareous

grassland.

The Semi-improved neutral grassland, mostly with coarser vegetation, has developed on

more nutrient-enriched soils. It is more common, both nationally and locally. The particular

form, i.e. with coarse grasses and hogweed (Heracleum sphondylium), occurs mainly on

roadsides.

The ‘poorer’ type of Unimproved neutral grassland, intermediate between the above forms

of neutral grassland, has corresponding value. It has the potential to develop into a more

herb-rich and less grass-dominated habitat with appropriate management (see section 5

below).

The Marsh/marshy grassland may be seen as a wetter form of the ‘poorer’, or the

‘standard’ type of Unimproved neutral grassland, where meadowsweet (Filipendula

ulmaria), often with coarse grasses, has increased in the absence of cutting or grazing. With

8


appropriate management it too has potential to develop into a more herb-rich habitat less

dominated by taller plants.

The Tall herb – ruderal habitat is represented by a single stand of rosebay willowherb

(Chamerion angustifolium) together with thistles (Cirsium sp). This has developed on

disturbed, more or less neutral soil with raised nutrient levels, probably with an added effect

from dumping of garden waste and throw-outs. It has negligible conservation value.

The various heathland and heath/grass habitats identified are somewhat modified examples

(by road drainage and probable mineral enhancement) of heathland habitats that have a

high conservation value both nationally and locally. However, these habitats are, with one

exception, common in Orkney and the value of particular sites is largely dependent on their

size and ‘naturalness’. Therefore these fragmentary and modified examples are of minor

conservation value. The exception is the Dry dwarf shrub heath – basic, an unusual and

herb-rich form of heath related to Unimproved calcareous grassland and of equal

conservation value.

Coastal grassland and Coastal heathland are represented by fine, species-rich examples

in the Yesnaby area, each supporting less common species.

Dune grassland and Open dune are represented by single sites in Burray, neither of them

outstanding, except for the oysterplant (Mertensia maritima) on the 4 th Barrier.

4.4 Outstanding verges

Road verges supporting particularly good examples of unmodified vegetation with

uncommon species and frequent ‘indicator’ species include the following.

Section

1 South of the Loch of Hundland

2 Most of the higher parts of the Lyde

Road

Habitats

‘Herb-rich’ Unimproved neutral grassland;

Unimproved calcareous grassland

‘Herb-rich’ Unimproved neutral grassland;

Unimproved calcareous grassland

3 North-east of Wilderness ‘Herb-rich’ Unimproved neutral grassland

4 Part of the Roundadee road

5 The western end of the Yesnaby road Coastal grassland

6 Much of the Bigswell road

Shorter sections of similar quality occur elsewhere.

Coastal heath;

‘Herb-rich’ Unimproved neutral grassland;

Unimproved calcareous grassland

‘Herb-rich’ Unimproved neutral grassland;

Unimproved calcareous grassland

4.5 Poorer verges

Sections of verge with poorer vegetation were found throughout the survey area.

Commonly, these sections are mixed in with others of better quality. Longer sections with

poorer vegetation include:

1. the Viewforth-Southbreck road, Burray;

2. part of the Hurtiso to North Ocklester Rd, Holm;

3. most of the Vensilly to A961 road in S Ronaldsay;

4. part of the Stymilders road, Stenness.

All these sections have abundant cock’s-foot (Dactylis glomerata) and much hogweed

(Heracleum sphondylium). The one in Holm has creeping thistle (Cirsium arvense).

9


5. DISCUSSION and RECOMMENDATIONS

5.1 General principles and rationale

The method of managing the conservation verges has been to cease mowing, in order to

allow plants to freely flower and set seed. Unfortunately, the response seen in the grassland

vegetation has been an apparent increase in the quantity of grasses, particularly of taller,

leafier species, and a few species of coarser broad-leaved plants, at the expense of the

smaller wildflowers. Such a development is predictable. It will be helpful to refer very briefly

to the ecology behind it, as this will be the basis for recommending future management.

Vegetation changes on the road verges result from interactions between the plant

communities involved, soil nutrient levels and management (or no management). Where

grassland on moderately fertile soils is left unmanaged, coarse, fast-growing plants benefit

and quite quickly occupy most of the space available below and above ground, suppressing

many smaller plants. Typically, these coarse plants include cock’s-foot (Dactylis

glomerata), false oat-grass (Arrhenatherum elatius), hogweed (Heracleum sphondylium)

and cow parsley (Anthriscus sylvestris). This is the effect seen in the Semi-improved

neutral grassland and the ‘poorer’ form of Unimproved neutral grassland. In damper

conditions, meadowsweet (Filipendula ulmaria) is one plant that can take over, and this is

the effect seen in much of the Marsh/marshy grassland and damper examples of neutral

grassland.

In less fertile soil the effect on the balance between coarser plants and smaller ones is much

reduced and the process slower, while, additionally, there are many plant species that have

evolved to take advantage of this environment. The conditions are therefore favourable for

many smaller species including colourful wildflowers and sedges to co-exist – as in

Unimproved calcareous grassland and the ‘herb-rich’ form of Unimproved neutral

grassland. The ‘standard’ form of Unimproved neutral grassland occupies a position

between these contrasting situations. In the least fertile soils and/or harsh environments the

end-point is often a different form of dominance – of one or very few ‘specialist’ species that

have evolved to cope with the stressful conditions, for instance heather (Calluna vulgaris) in

Dwarf-shrub heath and marram (Ammophila arenaria) in Open dune.

The effect of cutting (or grazing), appropriately managed, on the more fertile types of

grassland is to check the dominance of the coarser plants including grasses; or to put it

another way, grassland with an abundance of smaller wildflowers persists in more fertile

environments only where there is management, i.e. cutting or grazing, that inhibits the

dominance of coarser plants. In less fertile environments, the effect, and the necessity to cut

or graze in order to conserve species-richness, is less. The appropriate management

referred to is seasonal cutting or grazing that allows the smaller wildflowers to flower and set

seed. In the case of cutting this is usually once a year in autumn or thereabouts, possibly

twice a year in more fertile, growthy environments. (Heavy grazing or frequent, regular

cutting selectively favours some species that can withstand the treatment, especially grasses

because they re-grow almost immediately.) In the harsher, stressed environments

intervention to modify plant communities may be undesirable (for instance where marram

grass (Ammophila arenaria) stabilises sand dunes), unnecessary, or arguably necessary in

some cases to achieve certain aims (for instance in many heathlands).

The above summary indicates an approach to the management of each of the vegetation

types. However, if seasonal cutting is to be the chief action, because 93% of verges are

composed of neutral grassland of some kind and marsh/marshy grassland, it is an imperfect

solution, because cut grass material lying on the verge will tend to smother smaller, slowgrowing

plants, while more vigorous grasses and others will more quickly push through.

Clearly this will be more of a problem on the coarser verges where a quantity of material has

accumulated over the years. Removal of cuttings would therefore be highly beneficial. Also,

to move to a position where verges are much less coarse and more species-rich, a reduction

in soil nutrient status is necessary, and this requires cuttings to be removed. This summary

has not dealt with the more fertile and coarser verges that currently have no conservation

10


status, but these too would benefit from removal of cuttings, which should result in their

needing to be cut less frequently.

Further information on grassland habitat enhancement and creation can be found in ‘Habitat

Creation and Repair’ (Gilbert & Anderson, 1998).

5.2 Recommendations

1. It should be standard practice to cut all verges, but for a few exceptions, once a year in

autumn. Anytime after 1 st September is appropriate, though it is recognised that some may

have to be cut earlier for operational reasons: if so, it should not be the same verges every

year.

2. The method of ensuring that exceptions to the annual cut rule are made should be

twofold:

a) by identifying particular lengths of verge that will receive different treatments. These

are given in sections 4.4 and 4.5 above and fuller details are contained in Appendix 1.

Treatments for these will vary, and comprise cutting every two years, not cutting, and

the possibility of cutting twice in a year; and

b) by training of operators to recognise and appropriately treat some special kinds of

vegetation that have greater conservation value. They comprise:

• naturally very short grass;

• heather and other dwarf-shrubs;

• native willow (Salix sp) bushes.

It is not envisaged, for practical reasons, that operators travel all the Conservation

verges looking for poorer vegetation to be cut twice a year

In respect of a) cutting twice a year, this is offered as suggestion rather than a firm

recommendation. Two cuts may have slightly more effect in enhancing species-richness

than one late cut, especially if the first cut is in May (early enough to allow many plant

species to recover and flower later), but it will not be much in the absence of measures to

reduce soil nutrient levels, and this is dealt with in section 5.3 below.

In respect of b) training of operators, this should not present any real difficulties. The short

grass and heather are easily recognisable. The recommendation in the case of short grass

is that it is cut every 2 years, but if it were cut less or more this would not be critical: what is

important is that it is only cut late in the year and that it is not scalped (there is probable a

tendency on the part of operators to lower the cutter on shorter vegetation). In the case of

dwarf shrubs, the importance of not scalping is greater, as this will suppress these shrubs in

the longer term. For native willows (Salix sp), the recommendation is to trim them only as

much as necessary for road safety. The recommendation extends to other native bushes

including wild rose (Rosa agg) and honeysuckle (Lonicera periclymenum), though neither

was encountered on the Conservation Verges. Gorse (Ulex europaeus) (non-native) can be

cut back where necessary: it soon recovers.

It is envisaged that a half-day training session for operators would be sufficient. The main

points could be printed onto laminated cards to be kept in tractor cabs.

A remaining issue is weed control, especially of docks (Rumex sp) and thistles (Cirsium sp).

It is suggested that hand held-weed wiping is investigated, with advice taken from a qualified

adviser.

5.3 Further suggestions

As explained earlier, there are drawbacks to cutting without removing cuttings, and removal

has the great benefit of reducing soil nutrient levels. It is the standard management for

species-rich meadows on soil of moderate fertility. However, where nutrients are already

raised significant reductions in plant mass as a result of removing cuttings will take several

years. Where nutrients levels are lower the effect will be quicker.

11


It is recognised that the cost of removing cuttings on a large scale will be prohibitive, though

it should pay dividends in reducing cutting in the future. It is suggested that it is tried on

some sites. The most useful to try would be those of mixed quality, where the aim would be

to move the entire verge towards a more consistent quality and cutting regime in the future.

12


6. REFERENCES

Gilbert, O.L. & Anderson, P. 1998. Habitat Creation and Repair. OUP

Jackson, D.L. 2000. Guidance on the interpretation of the Biodiversity Broad Habitat

Classification (terrestrial and freshwater types): Definitions and the relationship with other

Habitat classifications. JNCC Report No. 37

Joint Nature Conservation Committee. 1993. Handbook for Phase 1 habitat survey.

Orkney Biodiversity Steering Group. 2002. The Orkney Local Biodiversity Action Plan.

Orkney Environmental Partnership

13


Appendix 1 - Verges data

Verge

no.

Road

no.

Name Parish Total

Length

(miles)

Survey

date

1 A966 Costa Hill, north verge only Birsay 0.21 10/07/08 U Neutral Grass (standard): 5

U Neutral Grass (poorer): 4

S-i Neutral Grass: 1

2 Durkadale Rd from Kirbuster

road junction to Deasbreck

corner, both sides

Birsay 2.23 30/07/08 U Calcareous Grass: 1

U Neutral Grass (herb-rich): 5

U Neutral Grass (standard): 3

Marsh/marshy grassland: 1

3 Hundland Rd (Kirbuster) from

A966 Twatt junction and

Durkadale road, both sides

Birsay 1.16 10/07/08 U Neutral Grass (poorer): 3

Marsh/marshy grassland: 7

4 Nisthouse Rd, both sides Birsay 1.24 10/07/08 U Neutral Grass (herb-rich): 4

U Neutral Grass (standard): 5

U Neutral Grass (poorer): 1

Phase 1 categories Target notes, comments Management

recommendations

Meadowsweet in coarse Unimproved

Neutral Grassland.

Northern marsh orchids in Unimproved

grassland.

One of the 2 or 3 ‘best’ verges surveyed,

especially the section nearest Hundland

Loch, with orchid species, grass-ofparnassus,

butterwort frequent. Also

downy oat- grass and hybrid jointed rush x

sharp-flowered rush.

Greater bird’s-foot trefoil abundant

between Hundland and Deasbreck corner.

There appears to have been ‘voluntary’

verge cutting for 300m west from

Guttersquoy westwards: to be

discouraged!

Meadowsweet almost throughout

A drier verge with very little meadowsweet

Poorest section furthest west on south

side

Annual late cut

Annual late cut,

except the section

both sides next to

Hundland, which

should be cut once

every 2 years

Annual late cut

Annual late cut

5 Littlequoy Rd, except first

500m from the A 961, both

sides

6 Northfield Rd, except first 300

m from A961, both sides

Burray 2.58 04/08/08 U Neutral Grass (herb-rich): 4

U Neutral Grass (standard): 4

S-i Neutral Grass: 1

Dry dwarf shrub heath –

basic: 1

A very mixed quality verge.

First 1 km westwards from start nearest

A961 is herb-rich on south verge, standard

on north.

Grassland around ND455968 for 200m

both sides approaches herb-rich maritime

grassland in quality.

Heath for 50m around ND454968 is close

to herb-rich coastal heath.

Last section south-west is semi-improved,

almost improved, with cock’s-foot

dominant.

Burray 0.7 04/08/08 Dune grassland: 9 First 100 m to electricity station is coarse.

Then shorter dune grassland

14

Annual late cut. Lift

mower over the

heathy bits.

Semi-improved

coarse grassland at

end could be cut

twice a year.

Annual late cut.


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

7 Viewforth-Southbreck Rd,

except first 50m at Southbreck

end, both sides

Survey

date

U Neutral Grass (poorer): 1

Burray 1.34 04/08/08 U Neutral Grass (poorer): 1

S-i Neutral Grass: 9

Phase 1 categories Target notes, comments Management

recommendations

A poor verge with much cock’s-foot and

hogweed. Red clover only occasional

8 No. 4 Barrier, east side only Burray 0.39 04/08/08 Open dune: yellow dune: 10 Mixed red fescue, sea couch and marram

with bare sand. At northern end, some

fore dune and strandline plants, including

sea sandwort and oysterplant (55 plants

between ND47919524 and ND47959529).

Scots Lovage at ND47999536

9 Jubidee Rd, except at junction

with A966, both sides

10 Whitemire Rd, Whitemire to

Breckan, both sides

11 B9057 Hillside Rd, from Borgie

houses to Wilderness, both

sides

1. from Wilderness to

Durkadale road junction

Evie 0.89 30/07/08 U Neutral Grass (herb-rich): 2

U Neutral Grass (poorer): 8

Evie 1.45 30/07/08 U Neutral Grass (herb-rich): 5

U Neutral Grass (standard): 2

S-i Neutral Grass: 3

Marsh/marshy grassland:


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

11 Hillside Rd, from Borgie

houses to Wilderness, both

sides - continued

2. from Durkadale road

junction to Borgie houses

12 Lyde Rd, from A966 to Lyde,

both sides

Survey

date

Evie/Birsay c. 4.69 2.

U Neutral Grass (herb-rich): 2

U Neutral Grass (standard): 7

S-i Neutral Grass: 1

Dry dwarf shrub heath –

basic:


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

Survey

date

14 Breck Rd, both sides Orphir 0.81 31/07/08 U Neutral Grass (standard): 6

U Neutral Grass (poorer): 2

S-i Neutral Grass: 2

15 Linnadale Rd, both sides,

except house frontage

16 A964 Orphir Rd, between Lintie

Brae and Smoogro Rd, south

verge only

Orphir 0.47 31/07/08 U Neutral Grass (herb-rich):


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

Survey

date

21 Waulkmill Rd, both sides Orphir 0.85 31/07/08 U Neutral Grass (herb-rich): 5

U Neutral Grass (standard): 1

Wet heath/acid grassland

mosaic: 1

Tall herb: non-ruderal: 1

Tall herb: ruderal: 2

22 Brodgar Rd, Ring of Brodgar

to Lyking road, both sides

Sandwick 3.24 28/07/08 U Neutral Grass (herb-rich): 2

U Neutral Grass (standard): 2

U Neutral Grass (poorer): 2

S-i Neutral Grass: 4

23 Roundadee Rd, both sides Sandwick 0.54 28/07/08 Coastal heath: 1

U Calcareous Grass: 2

U Neutral Grass (standard): 3

U Neutral Grass (poorer): 3

S-i Neutral Grass: 1

24 Yesnaby Rd, except for the

first 300m from the B9056

junction, both sides

Sandwick 3.25 28/07/08 Coastal grassland: 2

U Neutral Grass (herb-rich):


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

25 A961 Lythes Rd to Tomison’s

Academy, both sides

26 B9044 A961 – South Cara except for

the first 300m from the A961,

both sides

27 Aikers Rd, South Cara to

Vensilly, both sides

27 Aikers rd, Braehead corner –

A961 at Widewall, both sides

28 Haybrake Rd, Brandyquoy –

Aikers Rd, both sides

29 Kirkhouse Rd, Aikers Rd to

Wheems, both sides

South

Ronaldsay

South

Ronaldsay

South

Ronaldsay

South

Ronaldsay

South

Ronaldsay

South

Ronaldsay

Survey

date

Phase 1 categories Target notes, comments Management

recommendations

4.8 02/08/08 U Calcareous Grass:


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

30 Lowertown Rd, Gill –

Heatherbell, both sides

31 Uppertown Rd, quarry – end

of road, both sides

32 Windwick Rd, A961 –

Mossetter, both sides

33 Heathery Loan, except

between A960 and the

quarries, both sides

South

Ronaldsay

South

Ronaldsay

Survey

date

Phase 1 categories Target notes, comments Management

recommendations

1.05 03/08/08 Dry heath/acid grassland

mosaic: 1

Tall herb: non ruderal: 1

U Neutral Grass (standard): 1

U Neutral Grass (poorer): 1

S-i Neutral Grass: 6

0.96 03/08/08 U Calcareous Grass: 1

U Neutral Grass (herb-rich): 1

U Neutral Grass (standard): 8

South

Ronaldsay

0.36 02/08/08 U Neutral Grass (herb-rich): 8

U Neutral Grass (standard): 2

St Ola 0.68 30/07/08 U Calcareous Grass: 1

U Neutral Grass (herb-rich): 5

U Neutral Grass (standard): 3

U Neutral Grass (poorer): 1

A very mixed quality verge, with sections

of different quality inter-mixed.

Heath/acid grassland is quite rich, almost

a basic heath/calcareous grassland

mosaic.

Herb-rich sections at western end.

Unimproved calcareous grassland is close

to being a rich form of acid grassland

room for interpretation!

Herb-rich from A961 to West Mossetter L-

bend. Poorer after.

Some mown by householders.

Eastern section mainly herb-rich, poorer

by quarry

Annual late cut, but

avoid very short

heath/grass.

Annual late cut,

Annual late cut.

Annual late cut.

34 Stymilders Rd, both sides

except house frontages

Stenness 1.07 29/07/08 U Neutral Grass (standard): 4

U Neutral Grass (poorer): 1

S-i Neutral Grass: 5

Rank and weedy with much cock’s-foot at

the Stymilders end

Annual late cut.

Stymilders end could

be 2 cuts per year

35 Bigswell Rd, except for first

500m from A965, both sides

Stenness 2.97 29/07/08 U Calcareous Grass:


Verge

no.

Road

no.

Name Parish Total

Length

(miles)

Survey

date

36 Ireland Rd, both sides Stenness 2.95 07/08/08 U Neutral Grass (herb-rich): 1

U Neutral Grass (standard): 4

U Neutral Grass (poorer): 2

S-i Neutral Grass: 3

Phase 1 categories Target notes, comments Management

recommendations

Section from A964 to Settersquoy road,

and at other end 200m from Stenness

community centre westwards is mown.

A mixed verge with short and longer

sections of all grades of neutral grassland

Annual late cut.

21


Appendix 2 – Sample quadrat data for main vegetation types

Site Lyde road, west of Bluebraes brig Lyde road, just east of Bluebraes brig Smoogroo, east side of road

Veg height 80 cm 80 cm 35 cm

Phase 1 Neutral Grassland – semi-improved Marsh/marshy grassland Neutral Grassland – Unimproved

Phase 1 sub-category N/A N/A ‘Poorer’

BAP Priority Habitat None None None

NVC MG1a MG1b MG5a

DOMIN DOMIN DOMIN

Arrhenatherum elatius 7 6

Heracleum sphondylium 7 4

Festuca rubra 5 5 8

Dactylis glomerata 4 2

Lolium perenne 4 2

Holcus lanatus 4 4 2

Poa trivialis 4 4 4

Agrostis capillaris 3 4

Lathyrus pratensis 4 4 5

Ranunculus acris 4 2 4

Angelica sylvestris 4 1

Trifolium repens 4 4 3

Plantago lanceolata 2 4

Filipendula ulmaria 1 8

Trifolium pratense 1 4 4

Agrostis stolonifera 3

Leontodon autumnalis 3

Plantago major 3

Vicia cracca 1 1

Equisetum palustris 3

Taraxacum sp 1

Ranunculus repens 2

Anthoxanthum odoratum 3

Cynosurus cristatus 4

Poa subcaerulea 3

Rumex acetosa 2

Cerastium fontanum 2

Rhinanthus minor 1

Lotus corniculatus 3

Cardamine pratensis 3

Number of species 15 18 20

22


Site

Wheems X-roads to Brandyquoy, S

Ronaldsay

Wilderness, Dounby

Lyde road, west of summit

Veg height 25 cm 15 cm 10 cm

Phase 1 Neutral Grassland - Unimproved Neutral Grassland - Unimproved

Calcareous Grassland -

unimproved

Phase 1 sub-category ‘Standard’ ‘Herb-rich’ N/A

BAP Priority Habitat Lowland Meadow Lowland Meadow Upland Calcareous Grassland

NVC MG5a (/c) MG5c CG10b

DOMIN DOMIN DOMIN

Agrostis capillaris 4 3 3

Festuca rubra 7 5 4

Holcus lanatus 4

Lolium perenne 1

Anthoxanthum odoratum 4 4

Cynosurus cristatus 1

Poa subcaerulea 3 4 2

Trifolium repens 5 3 3

Lathyrus pratensis 4

Trifolium pratense 3 2 4

Plantago lanceolata 4 4 4

Ranunculus acris 3 3 3

Cerastium fontanum 3 3 1

Vicia cracca 4 3

Rhinanthus minor 5

Lotus corniculatus 5 5 4

Carex flacca 4 4 7

Plantago maritima 4 3 4

Carex panicea 3 5 5

Luzula multiflora 2 2 3

Euphrasia sp 4 4

Prunella vulgaris 1 1 4

Hypochaeris radicata 2

Bellis perennis 1 2

Leontodon autumnalis 2

Angelica sylvestris 4 2

Agrostis vinealis 4 4

Agrostis stolonifera 4 4

Carex nigra 5 3

Carex pulicaris 1 4

Potentilla erecta 3

Succisa pratensis 3 4

Lychnis flos-cuculi 1

23


Cardamine pratensis 1

Juncus articulatus 2 3

Juncus effusus 1

Dactylorhiza purpurella 1 3

Linum catharticum 2 4

Filipendula ulmaria 3

Equisetum palustre 4

Calluna vulgaris 3

Empetrum nigrum 3

Nardus stricta 4

Viola riviniana 4

Selaginella selaginoides 4

Hypnum jutlandicum 3

Alchemilla filicaulis 4

Danthonia decumbens 2

Pinguicula vulgaris 1

Galium verum 1

Ctenidium molluscum 1

Number of species 24 30 38

24


www.snh.gov.uk

© Scottish Natural Heritage 2010

ISBN: 978-1-85397-676-6

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Leachkin Road, Inverness IV3 8NW

T: 01463 725000

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