PRACTICAL ARABLE WILD FLOWER CONSERVATION

...Practical Arable Wild Flower Conservation on the Kemerton Estate - By J Clarke & C C Morgan July 2000

Summary
Kemerton Estate is in south Worcestershire – on the flanks of Bredon Hill – on soils varying from Limestone Brash, through heavy clays to sand and gravel soils and valley silt. Kemerton Conservation Trust (KCT) is a charity set up to promote nature conservation in the Bredon Hill area.  It advises the estate on conservation matters and manages specific conservation sites.

Other research at Kemerton and elsewhere has focussed on benefits for wildlife and costs of arable margins. This paper concentrates on the practical implications of establishing new sites and enhancing the botanical richness and diversity of existing sites.  The following points were considered:

We found that arable wild flower conservation margins were more easily established on sites with a basic, existing arable flora and without pernicious grass weeds. Kemerton follows a policy of using, whenever possible, seed sourced from within the estate boundaries. To achieve this and to obtain sufficient seed, KCT operates a wild flower nursery and has found that the period between initial seed collection and final sowing/planting covers from three to four years. It is important that seed collection, seed batches and later destinations are accurately recorded. It is also important to obtain accurate baseline data as well as ongoing monitoring of the project. Arable wild flower conservation margins may require additional management to control pernicious weeds or to clean the crop. To date it  appears that soil types (i.e. fertility) may influence the amount of management required to control pernicious weeds.  Success rates for sowing direct and planting plugs were similar.  The use of ‘cages’ to protect ‘introductions’ is important.  Costs of growing or purchasing seed will govern sowing rates but we aim to sow as much as possible.


Oathill Arable Margin

Introduction
The Kemerton Estate is owned by the Darby Family and is managed by Adrian Darby, formerly chairman of the Royal Society for the Protection of Birds and currently chairman of Plantlife. Since the early eighties it has tried to integrate farming and nature conservation and to set an example to other landowners and farmers. The estate comprises some 950 acres and is situated on the southwest slopes of Bredon Hill in Worcestershire, overlooking the Avon and Severn Valleys. It contains a diverse range of habitats and species.  These have been maintained and improved through sympathetic management of the farmed areas and by the establishment of specific estate ‘nature reserves’.

Since the early eighties, a full time conservation officer has been employed to manage conservation sites, monitor the wildlife of the estate and to work closely with the farm manager, P. Doble. This post is funded by the Kemerton Conservation Trust, a charity established by Mr Darby in  1989 to promote nature conservation on the estate and its surroundings.  

Aims
To investigate practical ways of enhancing existing ‘rich’ arable wild flower conservation margins and of establishing new sites.  

Background
Much research has already carried out by the Game Conservancy Trust and others into the effects on wildlife of arable conservation margins.

An earlier Conservation Officer at Kemerton, (Deane 1989), combined a great deal of earlier research to produce a report which described ‘expanded field margins’, including arable wild flower margins – comparing costs involved and benefits to wildlife.

Having accepted that much is to be gained by managing these margins, when establishing new sites and enhancing the botanical richness and diversity of existing sites the following questions were considered:

1 Selection of Margins
Robert Deane surveyed most arable margins  on the estate and identified two on Limestone Brash that were particularly rich.  Over the next few years, work continued on managing (farming) and monitoring the flora of these sites.

In 1997, as part of the restoration of a gravel pit on the estate into a nature reserve, a one hectare area that was unable to be quarried, due to the archaeological interest underneath was restored as a spring sown arable area, which is not harvested but left as a food source for wintering birds.

In 1998 two six-metre margins on wet, clay ground (Runway and Lakeside) were selected as possible arable conservation wild flower margins. They were chosen as they were on a different soil type and because there had been historical records for Corn Buttercup Ranunculus arvensis and both Sharp–leaved Fluellen Kickxia elatine and Round-leaved Fluellen Kickxia spuria in Lakeside. In 1999 Lakeside continued but as a 1/3 hectare sown wild bird cover under Set-aside.

In 1999 a 1/3 hectare headland on lighter soil – in Chapel field – was also selected under Set-aside.  A range of arable wild flowers had been identified on the overlapping ground between a wet-grassland conservation area and the arable crop.  The records included Petty Spurge Euphorbia peplus, Corn Mint Mentha arvensis and K. spuria.

In 1999 a six-metre margin on sandy soils in Welsh Furlong was selected to be investigated and was left unsprayed.  The margin is adjacent to a busy public footpath which is annually topped so does not have a Black-grass Alopecurus myosuroides problem.

This margin is currently under a two-year investigation. To date although no rarities have occurred, it has a good, basic flora with potential for enhancement.  As with the limestone headlands, numerous favourable comments have been received from people using the footpath.

In 2000 three further six-metre margins on the Limestone Brash and adjacent to the existing arable wild flower conservation margins, were selected under a Whole Estate Countryside Stewardship agreement.  

2 Provenance
 The Trust believes that seed should be sourced as close as possible to its intended destination.  This retains the genetic integrity. At Kemerton, wherever possible seed is taken from the estate.  However, for Shepherd’s Needle Scandix pecten – veneris, Corn buttercup Ranunculus arvensis and Field Gromwell Lithospermum arvense our nearest source is within ten miles - near Pershore. Corn Salad Valerianella locusta and V. dentata have been collected elsewhere on Bredon Hill.

3 Obtaining Sufficient Seed 
At Kemerton we have found that the viability and germination rate of arable wild flowers is unpredictable and therefore it is better to have as much seed as is realistically possible.  To achieve this, the Trust takes seed and grows the plants in ‘controlled conditions’.  For many plants a small patch of ground is used as an arable wild flower nursery.  The seeds of these species are easier to harvest.  It must also be considered that most arable plants flower and seed over a long period and harvesting will require numerous, time-consuming visits.  Poppy Papaver species shed seed when the seed pod is shaken and therefore must be harvested more frequently in windy conditions.  When harvesting seedpods of Night-flowering Catchfly Silene noctiflora it is important to check for the presence of larvae of moths such as Hadena confusa and Hadena bicruri which feed on the seeds of Silene species!  Some plant species, such as V. locusta, Venus’ Looking Glass Legousia hybrida and Scarlet Pimpernel Anagallis arvensis readily drop their small seeds.  These are grown in pots or trays in a cold greenhouse.  When flowering begins the pots are stood on sheets of paper that catch the seeds as they fall.  Every few days, the seeds can then be easily collected  The collected seed is stored carefully in individually labelled bags, within metal containers in cool conditions.

Some arable wild flowers germinate in autumn, some winter/spring and others in spring (Fitter & Attenborough, 1987) – and this must be born in mind when planning planting.

When planning a scheme of this type it must be noted that it may take three to four years to before sufficient seed has been produced.  At Kemerton, the plants have been introduced into sites both as seed and as ‘plugs’.

4 Recording
Each batch of seed collected from the wild is allocated a code number.  This comprises a number for the year, the Latin initials of the species and collection number.  For example 98/PA/1 is the code number for seed from Papaver argemone, collected in 1998 – from a particular site.  Further details are recorded on computer spreadsheets.  Subsequent seed collections from the original 98/PA/1 will be allocated a related code (e.g. 99/PA/1) and entered on computer. Example:

Scientific Name Common Name Provenance Date Collector Germination Sown Where Code No. Planted Out
Papaver argemone Prickly Poppy Oathill 5/7/98 JC Spring pot1/2/99 98/PA/1 Chapel Field

The spreadsheet also contains a space for notes.  

If Papaver argemone was also collected from a second site in 1998, then the code number allocated would be 98/PA/2.

5 Monitoring

a.  Existing Sites
As part of a ten-year monitoring strategy for the estate, these non-Stewardship margins are intensively surveyed in years 1,6 & 10. These intensive surveys are supported by annual casual observations.

The method used for intensive survey will be a fixed transect along the complete length of the margin, with a 1 metre quadrat 1 metre in from the edge, every 50 metres along the transect line. Presence and  % cover will be recorded for each species within the quadrat.  

b.  New/Stewardship Sites  
These will be monitored as above, but more frequently.  

This work is part of an estate-wide monitoring strategy supported under English Nature’s ‘Biodiversity Grant Scheme’.  

6 Management

a. Kemerton Lake  – Nature Reserve – sandy soils
The site is spring-sown with a mixture of Linseed, cereal and Quinoa as wild bird winter feed.  In addition, for two years attempts have been made to ‘bulk up’ the existing diverse arable wild flower population and to introduce other desirable species.  Aside from any direct wildlife benefits, this ‘reservoir’ of Kemerton plants has two other functions – to act as a ‘reserve’ population should disaster occur elsewhere, and to provide a demonstration area for visitors.

As the site is on a nature reserve, several problems have been identified.   Sowing dates usually follow on from the main farm spring sowings, thus providing later grazing for pigeons and rabbits.  The site supports a large rabbit population.  Efforts are being made to fence out and cull the rabbits.  It is interesting to note that rabbits appear to locate and selectively feed on the native, introduced plants.  In addition, up to 50 Canada Geese attempt to breed in or near the reserve and heavily graze the arable area.  In future culling will take place under licence.

Attempts to protect seed and plants of introduced arable wild flowers by use of individual wire cages have been partially successful – geese can reach inside and rabbits and hares may pull them over. An improved design trialled in Chapel field (see below) will be used in the future. Common Couch Elymus repens  is a problem on the site. The method that will be trialled later this year is spraying of ‘ Roundup’ on the affected area once all the cover crops and arable wildflowers have set seed. This will kill all the plants, including the E. repens, but leave unaffected the shed arable wildflower seed and the seed on the crop which will be eaten by the wintering birds.

b.  Chapel Field – heavy soils
In autumn 1999 this headland was sown with a ‘Wild Bird Cover Crop’ under set-aside and will therefore not be harvested.  A light dressing of fertiliser is permitted. A. myosuroides was not sprayed in 2000 but will need to be controlled in the future.  As mentioned earlier, this site had already been identified as a ‘good’ arable wild flower site. Trials are taking place to introduce further suitable species.  These have been planted as seed and/or plugs in 2m square wire exclosures, ½ metre high - low enough to avoid the spray boom.  This method has proved hugely successful by eliminating grazing problems and in providing a favourable microclimate for germination and growth.  To protect any genetic integrity, it was decided that should any introduced species be found outside the cages during the first year, then the introduced plants would be destroyed.  This cage design will be used on other sites.  Chapel Field is proving to be an important arable wild flower area on the heavier soils.  

c.   Runway Field and Lakeside – Heavy clays
In autumn 1998, these headlands were planted with wild flower seed.  In spring 1999 wild flower plugs were planted.  The extreme soil conditions in this wet clay and rabbit grazing resulted in apparent complete failure.  In autumn 1999 a further attempt was made in Lakeside, using the larger cages (as described for Chapel Field).   This has been a partial success – Scandix pecten - veneris and R. arvensis  thrived best.  In addition, several plants of the former were found outside the exclosures – probably seed from 1998. A. myosuroides was not sprayed in 2000 but will need to be controlled in the future.  Lakeside would appear to have limited potential but trials should continue.

d.  Welsh Furlong – Sands and silts
This trial headland is not included in any current conservation or agri-scheme.  Because of its possible floristic interest no species introductions will be tried until the end of a two-year monitoring period.  

e.   Stewardship Sites – Limestone brash
Existing (pre-2000) sites – Oathill North and Westmancote Piece East.

These headlands had been identified by Deane (1989) and have been managed for their arable wild flower interest since then.  Indeed, they have been the main seed source for the arable wild flower project at Kemerton.  They are sited next to grass margins/footpaths, and invading grass has been a localised problem but can be controlled with sprays.  Some of the seed and plants produced in the nursery have been planted back into the headland – to ‘bulk up’ the existing seed bank.  Apart from regular monitoring it is unlikely that further management will be required.  These headlands are used as demonstration sites for visitors to Kemerton Estate.  

New (post-2000) sites – Westmancote Piece South, Westmancote Piece North, Oathill East and Pad Piece North – Limestone brash.

Because of the botanical importance of the neighbouring arable headlands, the opportunity to increase the number of conservation headlands was taken under the Countryside Stewardship Scheme.  Kemerton Countryside Stewardship margins are different from ‘normal’ Countryside Stewardship margins as the headland can be cropped. Once the monitoring programme has assessed their floristic value, a decision on whether to carry out ‘bulking up’ or an introduction programme will be made.  From experience gained on the existing sites, it is likely that some control of invasive grasses will be necessary.  

Conclusions/Recommendations
It is not always easy to produce a good arable conservation margin – particularly on heavy/wet ground or where few arable wild flower species occur naturally.  Generally, a soil of low fertility will ensure that the site is not dominated by pernicious weeds and that the arable wildflowers do not compete too much with the crop. (P. Doble pers. com.)

Broad-leaved crops such as brassicas and beans in a crop rotation provide a good opportunity to control A. myosuroides and Wild Oat Avena fatua using graminicides whilst leaving arable wildflowers relatively unaffected.  However, graminicides sometimes seem to affect wildflower seedlings (P.Doble. pers. com.)

Grass adjacent to arable wildflower conservation headlands should be regularly cut to prevent the grass seeding into the headland.

Spring-sown cereals tend to have a less dense canopy than autumn sown crops.  However, some arable wildflower seeds germinate in the autumn.

Rabbits appear to selectively graze ‘native’ plants in preference to planted crops.

Where rabbit populations are high, establishing an arable wildflower conservation margin may be very difficult.

Growing arable wildflowers in nursery or greenhouse conditions is labour-intensive.  However, harvesting is easy and the maximum quantity of seed can be collected.

Our results show that success rates for planting seeds directly into newly sown headlands and planting out pot grown plugs are similar.  Therefore in most circumstances it is preferable to sow direct.

The use of cages to protect seedlings during the first year or two of introductions is preferred, however only small sections need protection.

It is not possible to recommend sowing rates.  However, to avoid repeating the process it is better to sow as much seed as is practical and affordable.

At Kemerton it is recommended that suitable sites for arable wild flower conservation margins be eventually established on examples of all soil types.  The area available for conservation will always depend on current farm practice and policy.  Meanwhile, in the next few years trials should take place on sites that still retain some interesting plant species, or from where past records indicate potential. Sites already identified include a section of Runway Field (old record of Cornflower Centaurea cyanus), other sections of Lakeside, Deer Field (80’s records of R. arvensis and both Kickxia spp.), Butchers, Long Ground, and Welsh Furlong (already being investigated).

Ideally, other farmers should be encouraged to follow Kemerton’s example regarding the sourcing and growing of wild flower seeds.  As arable wildflower conservation margins are now part of Countryside Stewardship and (indirectly) affected by Set-aside rules, additional financial support should be made available for farmers who retain the local genetic integrity of arable wild flowers.

Some farmers may not have the resources to collect and grow seed in the way that Kemerton does - nor may they be aware of local seed sources. Therefore both local and centralised information is required.  This could be compiled and held at national level by Plantlife, Flora Locale or at local level, by FWAG.  Additionally, a network of regionally appointed nurseries could supply seed of local provenance.  

Acknowledgements
Thanks to A.M.G.Darby and P.Doble for comments on the early draft and M.J.Morgan for reading final draft.    

Bibliography

Appendix 1                              Kemerton Arable Wildflower Trials

a.  Aims - To ‘Bulk Up’ Existing Conservation Sites

Year One

Collect Seed From Existing Site
Label and Record

Year Two

Plant Seeds in ‘Controlled Environment’
Sow ‘Fine’ Seeds in Greenhouse in trays and in plugs
Plant out Plugs in Headlands - in Spring - Record
Harvest Seed from Greenhouse and Nursery in Summer – Label and Record  

Year Three
Sow some (or all) Seed Direct into Headlands

Year Four
Sow Direct Into Headlands

b.   Aims - To Introduce/Re-introduce Arable Plant Species into New/PreviousSites

Year One
Collect Seed From Nearest Local Source - Label and Record                                       

Year Two
Plant Seeds in ‘Controlled Environment’
Sow ‘Coarse’ Seeds in Nursery and some in Greenhouse as Plugs
Plant out Plugs in Headlands - in Spring - Record
Harvest Seed from Greenhouse and Nursery in Summer – Label and Record

Year Three
If more Work is Required  - Repeat Year Two

Year Four
Sow Direct Into Headlands  

Appendix 2      Arable Wildflower Species List For Kemerton Estate

Scientific Name Common Name

Aethusa cynapium   

Fool’s Parsley

Agrostemme githago   

Corn Cockle (introduced)  

Alliaria petiolata   

Garlic Mustard

Alopecurus myosuroides   

Black Grass

Anagallia arvensis   

Scarlet Pimpernel

Aphanes arvensis   

Parsley Piert

Atriplex patula   

Common Orache

Barbarea vulgaris

Wintercress

Brassica nigra

Black Mustard  

Bromus sterilis

 Sterile Brome

Capsella bursa-pastoris

Shepherd’s Purse

Centaurea cyanus

Cornflower

Cerastium fontanum

Common Mouse-ear

Chaenorhinum  minus

Small Toadflax

Chenopodium album

Fat Hen

Cirsium arvense

Creeping Thistle

Conium maculatum

Hemlock

Coronopus didymus

Lesser Swinecress

Coronopus squamatus

Swinecress

Dactylis glomerata

Cocksfoot Grass

Euphorbia exigua

Small Spurge

Euphorbia helioscopia

Sun Spurge

Euphorbia peplus

Petty Spurge

Fallopia convolvulus

Black Bindweed

Fumaria officianalis

Common Fumitory

Galium aparine

Cleavers

Geranium dissectum

Cut-leaved Cranesbill

Geranium molle

Dove’s Foot Cranesbill

Hypericum perforatum

Perforate St.John’s Wort

Kickxia elatine

Sharp-leaved Fluellen

Kickxia spuria

Round-leaved Fluellen

Lamium amplexicaule

Hen-bit  Deadnettle

Lamium purpureum

Red Dead-nettle

Legousia hybrida

Venus’ Looking Glass

Lepidum campestre

Field Pepperwort

Lithospermum arvense

Field Gromwell (introduced)

Matricaria matricarioides

Pineappleweed

Matricaria recutita

Scented Mayweed

Medicago lupulina

Black Medick

Mentha arvensis

Corn Mint

Papaver argemone

Prickly Poppy

Papaver dubium

Long-headed Poppy

Papaver hybridum

Rough Poppy

Papaver lecoqii

Babbington’s Poppy

Papaver rhoeas

Common Poppy

Persicaria maculosa

Redshank

Ranaunculus arvensis

Corn Buttercup (re-introduced)

Raphanus raphanistrum

Wild Radish

Reseda lutea

Wild Mignonette

Reseda luteola

Weld

Scandix pecten-veneris

Shepherd’s Needle (introduced)

Sheradia arvensis

Field Madder

Silene alba

White Campion

Silene noctiflora

Night-flowering Catchfly

Sinapsis arvensis

Charlock

Sison amomum

Stone Parsley

Sonchus asper

Prickly Sow Thistle

Stellaria media

Common Chickweed

Thlapsi arvense

Field Pennycress

Triplospermum inodorum

Scentless Mayweed

Urtica dioica

Common Nettle

Urtica urens

Small Nettle

Valerianella dentata

Narrow-fruited Corn Salad (introduced)

Valerianella locusta

Corn Salad  (introduced)

Veronica agrestis

Green Field Speedwell

Veronica arvensis

Wall Speedwell

Veronica persica

Field Speedwell

Veronica polita

Grey Field Speedwell

Viola arvensis

Field Pansy

Viola tricolor

Wild Pansy

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