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Published in Issue No. 154, page 1 to 5 - (23332) characters
Hebridean and Shetland oat (Avena strigosa Schreb.) and Shetland cabbage (Brassica oleracea L.) landraces: occurrence and conservation issuesM. Scholten Nigel Maxted B.V. Ford-Lloyd N. Green
In 2003, the Department of Environment, Food and Rural Affairs (DEFRA) of the UK commissioned a national inventory of genetic resources for food and agriculture (GRFA). For Scotland, the inventory identified several Scottish landraces: Scots, a Phleum pratense L. landrace, produced in the Stirling area and included in the UK National List; bere barley (Hordeum vulgare L.) and black oat (Avena strigosa Schreb.) varieties in the Hebrides as well as the Shetland and Orkney Islands; Shetland Black potato; Lewis Black potato; and Shetland Cabbage (Brassica oleracea). With the exception of the Scots forage landrace, all extant landraces were restricted to the Northern and Western Islands of Scotland, and for some there was anecdotal evidence of threat. Shetland cabbage, which has been cultivated on the Shetland Islands for centuries, was considered seriously threatened. A. strigosa seed production on the Western Isles had been described by several observers as hampered by increasing numbers of greylag geese eating and soiling the crop. Data on the exact extent of cultivation were not available, and fieldwork to determine the actual extent of cultivation of the landraces fell outside the scope of the National Inventory of 2003. Two research projects in 2006, one as part of an MSc research project (Lever 2006), had therefore as their objectives to assess the extent of current cultivation and to assess conservation issues and needs of A. strigosa and Shetland Cabbage.
A. strigosa has been found in archaeological sites in Great Britain dating back to the 15th century (Dickson 1996). At the end of the 18th century, the diploid A. strigosa was almost entirely replaced by hexaploid A. sativa types (Hunter 1924), and A. strigosa became restricted to the poorer soils on the higher grounds in Central Scotland, the Northern and Western Isles (Findlay 1956), and Wales (Chater 1993). It was used for feed, thatch, baskets, furniture and as famine food (Findlay 1956; Fenton 1978, 1999).
On the Shetland Islands, replacement of A. strigosa by A. sativa types did not start until the 1930s, and some crofters retained A. strigosa, especially in north Mainland and Yell (Scott and Palmer 1987). Its cultivation almost ceased a few years ago, apart from a couple of farmers, and a project has recently been initiated on the islands to encourage and increase the cultivation of heritage crops such as bere and Shetland oat (http://www.organics.shetland.co.uk).
Current cereal cropping on the Hebridean islands is restricted to the Machair coastal grasslands, a UK priority habitat, listed in Annex 1 of the EU Habitat Directive (Angus 2001; http://www.ukbap.org.uk/habitats). A. strigosa mixed with rye was the dominant cereal on the Machair soils in the late 1980s, due to its modest requirements for fertilizer, its ability to stand manganese and copper deficiencies, and the cheapness of its home-produced seed (NOSCA undated). However, official agricultural statistics have shown severe declines in (unspecified) cereal crop production for the Western Isles in recent years, especially on Harris and Lewis, and to a lesser extent on North Uist (http://www.cne-siar.gov.uk/biodiversity). Depopulation because of a lack of local employment and an ageing farming population are major social issues affecting cereal production, with increased sheep husbandry replacing cattle being one of the major agronomic causes of decline. Most of the farming is part-time and the main source of income is off-farm employment.
As a weed, A. strigosa Schreb. has shown a dramatic UK-wide decline in the last thirty years because of changing agricultural practices (Preston et al. 2002). It is not included in the UK threatened plant list because it does not naturalize (Cheffings et al. 2005; Preston 2005 pers. comm.). In Ireland, it is part of the Heritage Cereal Project and has been sampled for the Irish Threatened Plant Genebank (www.issa.ie). Beyond the British Isles, it is a species in severe decline (Podyma 1993, 1994; Weibull 2001; Kiec 2003; Bettencourt 2005, pers. comm.).
A. strigosa: Materials and methods
The field survey concentrated on the southern islands of the Outer Hebrides, north-western Scotland, North Uist, Benbecula and South Uist, which form the main area of A. strigosa cultivation. Fields were visited starting mid-August 2006, when the crop was maturing. Crofters were contacted through local conservation and agricultural extension agencies or directly, and were questioned about their agronomic practices and the Hebridean local A. strigosa in particular. Conservation concerns and plans were discussed with the local biodiversity officer, local branches of conservation groups such as the Royal Society for the Protection of Birds (RSPB) and Scottish Natural Heritage (SNH), and the local area office of the Scottish Environment and Rural Affairs Department (SEERAD).
A. strigosa: Results
The location of the Scottish Islands is shown in Figure 1 and the major area of A. strigosa cultivation is indicated by the box. All main cereal growing areas of North Uist (Berneray included), Benbecula and South Uist were visited, and over 350 cereal fields were observed. Of these, only two fields were found with A. sativa, both in a mixture with A. strigosa. Most cereal fields observed were therefore A. strigosa in mixture with rye or rye and bere barley.
While silage, and to a lesser extent combining, prevail as harvesting methods, the traditional method of binding into sheaves and stacks is still practised by a minority of crofters.
In comparison with the Hebridean Islands, the scale of A. strigosa cultivation on the Shetland Islands is small: of the four known growers of A. strigosa, only three grew A. strigosa in 2006, on a total of 0.8 ha, for thatch for heritage buildings, for basketry and chairs.
It was beyond the scope of this study to assess the number of seed plots for the Hebridean A. strigosa. Seed saving is risky due to the short window of opportunity, and the risk of greylag geese eating or spoiling the ripe seed. The small seed growing areas are especially vulnerable to greylag geese damage, after the main fields have been cut as silage. One of the driving forces behind the transition to silage has been earlier harvest to avoid goose damage. The greylag geese population on the Outer Hebrides, protected by law and two large nature reserves, has doubled in the last ten years and is a problem for crofters as well as conservation agencies. The now predominant harvesting method of silage may have reduced the number of seed producers, and the seed shortages observed in recent years have to be attributed to the complex of factors of threats arising from geese, weather, and changing harvesting methods. Farmers interviewed saw the main problems of continued cultivation of the oat being diseases and greylag geese. Smut has been a problem, having wiped out part of the seed crop some years ago. The other widespread problem is greylag geese eating the crop when it is maturing, and soiling the silage. Asked about the future of the oat, interviewees would relate this to the future of farming in general, the problem of depopulation of the islands, an ageing farmer population, and the increase in sheep husbandry.
The first reference to cabbage on the Shetlands can be traced back to 1615 (Fenton 1978). It has traditionally been grown as winter feed for cattle, and its cultivation has contributed two distinct structures to the Shetland landscape: ‘plantie crubs’ and ‘kale yards’. Plantie crubs are small stonewalled nurseries (Figure 2), used for growing seedlings. The plantie crubs are situated on wind-sheltered, low fertility soils to prevent young plants from growing too tall and affected by the high winds. Young cabbage plants are transplanted to the larger kale yards, which traditionally had natural stone walls to exclude grazing animals. In contrast to the plantie crubs, the kale yards are situated on richer soils and are fertilized, usually with manure.
A collection mission for Shetland cabbage had been undertaken in the 1980s, resulting in a dozen accessions for ex situ storage and an evaluation study into disease resistance, showing moderate tolerance for clubroot (NOSCA undated).
Shetland cabbage: Materials and methods
Cabbage growers were contacted through the agricultural extension division of the Scottish Agricultural College and the Farming and Wildlife Advisory Group. The survey was also announced through BBC Radio Shetland. Visits to islands where cultivation was expected to occur resulted in direct observations of kale yards and direct additional contacts. Growers were informed about the purpose of seed collection, and were interviewed in a semi-structured form about their motives for growing the cabbage, the origin of their stock, and their horticultural practices.
Shetland cabbage: Results
Of the Shetland Islands, north, west and south Mainland, Foula, Bressay, Whalsay, Yell and Unst were visited, and the islands of Papa Stour and the Outer Skerries were assessed by telephone. An estimated 50 kale yards in use were observed, spread over these islands, and 37 cabbage growers were interviewed. Up to the 1970s, kale yards of thousands of plants had been normal, but now only 6 out of 50 were of this size, while half of the kale yards had less than 500 plants. The number of active seed and transplant producers was even smaller: less than half of the growers interviewed had grown their own seed and seedlings this year; the others had obtained transplants from neighbours or relatives, or purchased through advertisements or commercial outlets. However, there was a small group of active seed growers, each with three active plant nurseries. These growers were retired from other activities, and many were in their eighties. One plantie crub can produce ten thousand young cabbages, provided the plants survive the critical winter period. One commercial outlet in Lerwick sold 7200 cabbage plants this spring—out of a total observed or estimated 56 000 plants on the islands, i.e. about 12% of all cabbages. As in the case of A. strigosa, this restriction of seed production to a small number of seed growers may have an adverse impact on genetic diversity.
The traditional usage of cutting and feeding cabbage leaves to dairy cows in winter had been largely replaced by feeding whole cabbages to lambs or cows during the winter months. Some growers would use the cabbage in traditional ‘tattie’ soup with potatoes, and one grower used the cabbage for demonstration purposes – for tourists. Crofter motivations to grow the Shetland cabbage were based on its adaptation to Shetland’s climate and the fact that it was a good source of vitamins and minerals. Some growers would emphasize its value as inexpensive home-grown winter feed, while others concluded it was more expensive than commercial synthetic feeds if labour costs were included. Many growers would emphasize the hobbyist nature of growing cabbages and the traditional nature of working the plant nurseries. Most growers were retired and grew plants for their children, who themselves having full-time jobs off-farm, had no time for cabbage cultivation.
Shetland cabbage: collecting seed for ex situ conservation
Seventeen seed samples were collected from Shetland Mainland, Foula, Yell and Whalsay for ex situ conservation in the seed bank at the Scottish Agricultural Science Agency (SASA) in Edinburgh, UK. Germination tests on the collected material showed one dead sample, three samples with germination rates of <50%, but five of the samples had germination >85%. Seed donors received confirmation of their donation, information about the germination test, and were requested to return a letter of consent to SASA to allow other users access to their material. This protocol was developed as part of the Scottish Landraces Protection Scheme (SLPS), launched at SASA last year (Green 2006 pers. comm.). Landrace seed donors can request some of their seed back in the event of a bad seed harvest, so the SLPS provides a seed safety deposit system.
No information on either A. strigosa or Shetland Cabbage could be found in official agricultural statistics. Cereal production for the Outer Hebrides has been listed as either barley, oat or mixed grain without further specification. For both crops, field work was required to determine the extent of occurrence. Field work verified official agricultural statistics listings for the Western Isles: 99% of oat found on the Western Isles was A. strigosa, while in two fields, A. sativa was mixed in. The 318 ha of total cereal cultivation listed in SEERAD statistics for the Western Islands for 2005 are therefore almost entirely A. strigosa landraces mixed with rye and bere.
Weibull et al. (2001) gave an overview of work done on A. strigosa in the rest of Europe and reported it extinct in Denmark but present at four locations in Lithuania. It is a very rare crop for Portugal, grown on very poor soils (Bettencourt 2005, pers. comm.) As such, North Uist, South Uist and Benbecula are probably the largest areas of cultivation and occurrence in north-western Europe. However, its cultivation on the Outer Hebrides has decreased considerably since the 1980s: from about 1400 ha to about 400 ha in the last five years. Although still widely grown, a future decline seems inevitable, with a rapidly decreasing and ageing population, a seed production system losing resilience because of fewer seed producers, increased use of silage, a short harvesting period, and high greylag geese numbers.
Although differing in extent of cultivation, both A. strigosa and B. oleracea landrace seed production may be declining faster than the cultivation itself, and for Shetland cabbage it has become largely an activity of the oldest growers. Knowledge of seed production is likely to be lost as dissemination to the next generations of farmers and growers will become more limited. This has serious implications for genetic erosion, as well as for conservation actions. Shetland cabbage cultivation is now restricted to very few growers. Of the 1200 agricultural units, less than 5% were involved in cabbage cultivation. It seems likely that transplants sales will become more concentrated in a few commercial outlets, and this is likely to have a negative impact on genetic diversity.
The Hebridean oat seed production system appears to have become less resilient, as indicated by incidences of disease, seed shortages in recent years, fewer active crofters and a possibly decreasing window of opportunity for harvesting seed due to climate change, i.e. wetter summers. No seed safety multiplication programme is currently in place. Targeting seed production for the Hebridean A. strigosa local varieties seems a crucial measure for its longer-term in situ conservation. The RSPB has recently funded traditional harvesting methods (RSPB and SCF 2004), but this project is a short-term measure. Local seed production is also an Action Point of the Local Biodiversity Action Plan for cereal field margins of the Machair on the Western Isles, in which integrating local seed production in Land Management Contracts is proposed (http://www.cne-siar.gov.uk/biodiversity).
Weibull (2001) has argued that in situ conservation measures for A. strigosa would best be done by subsidies. Accrediting growers of landraces through EU Single Farm Payment Schemes as proposed for the Western Isles may be the most efficient mechanism for ‘on-farm’ conservation. The case of the Scottish landraces shows that the seed production, in particular, of landraces should be targeted in these schemes. Beyond subsidies however, additional market incentives may be needed to motivate farmers, and perhaps the most beneficial conservation action would be a review of the marketing potential of the Scottish landraces if one wishes to conserve this unique European resource.
A first necessary step will be the recognition of landraces as ‘local varieties in need of conservation’. There is limited awareness of the existence of local varieties or landraces in current national conservation planning. National recognition of landraces would stimulate and support local conservation initiatives, such as the Local Biodiversity Action Plan for the Machair on the Outer Hebrides, or the Community Biodiversity Action Plan for the Yell area, which listed Shetland oats and Shetland kale (Shetland cabbage) as Species of Concern (Grey 2003).
Fieldwork on A. strigosa was funded by a Science and Research Grant from the Botanical Society of the British Isles (BSBI). Shetland cabbage fieldwork was funded by the University of Birmingham (UOB) and Mr Andrew Lever was co-worker. ArcView maps were prepared by J. Magos Brehm (UOB). The National Inventory of UK GRFA was initiated and funded by the Department of Environment, Food and Rural Affairs (DEFRA - CSA6461).
Professor G. Dixon; Dr D. Astley, HRI; Mr Graham Fraser, SAC Lerwick; Mrs Sue White, Mr R. Eunson, FWAG Lerwick; Mrs Anna NicGill’Fhaolain, Biodiversity Officer, Balivanich; Mr W. Muncaster, SEERAD, Balivanich; Mr C. MacPhail, SAC, Balivanich; Mr Jamie Boyle, RSPB, North Uist; Mr Gwyn Jones, EFNCP, Steve Duffield, South Uist; and Mr W. Scott, Scalloway, are acknowledged for advice and information. Crofters and farmers on the Shetland Islands and the Outer Hebrides are kindly acknowledged for their time, information and hospitality.
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