Recording cereal field margins in Countryside Survey 2000  Module 3 final report (part 1)

by
L.G. Firbank, L.R. Norton and S.M. Smart
Contact: Les Firbank (lgf@ceh.ac.uk). CEH Merlewood, Windermere Road, Grange-over-Sands, Cumbria, LA11 6JU, UK

Note: Module 3 consists of two surveys of key agricultural habitats: cereal field margins and hedgerows. This report relates to part 1, the survey of cereal field margins. The report on part 2, the hedgerow survey, will be available separately.

Contents

• Executive Summary - HTML
• Full report - PDF, 83 Kb
  

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Executive Summary

1. This project involved a new survey of arable field margins across Great Britain, undertaken as part of Countryside Survey 2000 (CS2000), introduced to provide information on the plant species occurring within this Priority Habitat.

2. The vegetation of 569 1 km squares was surveyed in 1998 – 99, selected on a stratified random basis. Arable field margin plots were established adjacent to a CS2000 boundary plot, whenever it was located within an arable field.

3. The arable margin plots measured 100 m along the cultivated edge (this may involve including a second or third side of the field and one or two corners) x 1 m extending into the crop from the boundary of the cultivated land. All plant species were recorded within the plot, along with other observations, notably the crop type (nb. some of these other observational data are missing, reducing the sample size for certain analyses). The field surveys took place between June and October 1998, except for 18 plots surveyed in late spring 1999.

4. A total of 547 plots were recorded. 40 plots included neither crops nor other arable plants; these may have been sterile strips or, more likely, were surveyed shortly after cultivation. These plots are excluded from all further analyses. The remainder were found mostly in Zone 1, that includes the largely arable areas of eastern England and Wales; Zone 2, that includes the western lowlands of England and Wales, and Zone 4, the lowland of Scotland. In addition, five plots were recorded in Zone 3, the uplands and marginal uplands in England and Wales, and one in Zone 5, the marginal uplands of Scotland. All plots are included in the GB analyses, but only Zones 1, 2 and 4 are reported separately.

5. The mean species richness per plot (excluding crops and volunteers) was 14 across the whole of GB, showing substantial variation in each of the Zones. Species richness was in general greatest in Zone 2 (mean of 15.5, as opposed to 13 for the other zones). There were significant differences between the major crop categories (F_5,451 = 5.64, P < 0.001), but with much overlap (Fig 3); cereals had significantly fewer species per plot than root crops and vegetables (p < 0.05).

6. A total of 294 non-crop species were recorded on the arable margins. Of these, only 110 were recorded ten times or more, and 117 occurred in only one or two plots. The most frequent were Cirsium arvense, Galium aparine, Elytrigia repens, Poa annua, Urtica dioica, Anisantha sterilis, Rumex obtusifolius, Arrhenatherum elatius, Convolvulus arvensis, Stellaria media, Polygonum aviculare agg. and Veronica persica. Of the other major arable weeds, Avena fatua and Alopecurus mysoroides were ranked 28 and 37 in frequency. No species listed in the UK Biodiversity Action Plan were recorded, nor were any of the species listed as extinct, rare or scarce species. Nevertheless, some species were of conservation interest, including Kickxia spuria, K. elatine and single records of Chrysanthemum segetum and Silene noctiflora. There were frequent records of species that are important food plants for birds, e.g Stellaria media and Polygonum aviculare agg.

7. The most frequent weeds are those plants that are typical of nutrient-rich situations, including Cirsium arvense, Galium aparine and Urtica dioica. Many of the species are likely to have appeared in the crop edge from the field boundary; they include, again, G. aparine and U. dioica, as well as woody species that will not be able to establish in this habitat (e.g. Crateagus monogyna). There were several species typical of grassland; they include Holcus lanatus, Ranunculus repens and Bellis perennis. The broad-leaved weeds that are considered as important food for animals (e.g. Polygonum spp.) remain widespread. Some of the more unusual arable plants were recorded, but none of the scarce or rare plants, suggesting results suggest that the scarcity of such plants is genuine, and does not simply reflect under-recording.

8. The vast majority of arable field margins contain between five and 20 non-crop plant species, and, secondly, that these species are likely to contain a high proportion of perennial weeds, including those that may be difficult to control. The differences in species-richness between crops may reflect differences between farming systems, regions and sowing dates, and are unlikely to have agronomic consequences in themselves. Multivariate analyses of species composition suggest no other patterns strong enough to influence weed management to any great extent.

9. The weed florae of western England are, in general, more species-rich and richer in broad-leaved weeds than those in eastern GB. The changing rank order of weed frequency may suggest a decline in those species of importance to animals. In particular, Stelleria media, a food plant for birds including finches appears to have declined in rank order of occurrence compared with previous whole field surveys.

10. A full assessment of changes in the weed flora for GB since 1978 will be considered separately, as part of the analysis of the other CS2000 plots. In the meanwhile, these results present the clearest information about the current status of crop edge vegetation, and they also provide an important baseline for assessing changes in the future. Given the rapid changes in farm management, and the conservation importance of the arable margin habitat, such a baseline will prove invaluable in the future.