Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

The effects of different crop stubbles and cereal straw disposal methods on wintering birds and arable plants - BD1610

Description
Background
Many species of farmland bird have undergone rapid population declines and range contractions in the last 25 years. Annual plant species associated with arable land are proportionally the most threatened group in the UK Red List of Vascular Plants. Many of these cornfield flowers have become rare and some are extinct. There is growing evidence to suggest that these changes have been caused, either directly or indirectly, by agricultural intensification. One of the most widespread and dramatic agricultural changes that has taken place is a switch from spring-sown to autumn-sown cereals with the subsequent loss of winter stubbles. It seems likely that this switch in cropping regime has had a detrimental impact on farmland birds for a number of reasons; stubbles (including those created by rotational set-aside) are known to be important and preferred winter feeding areas for many species; declines of many farmland birds are linked to changes in survival, probably related to over-winter mortality, rather than breeding success; trends in abundance of finches and buntings (seed eaters) are particularly strongly associated with changes in sowing regimes which reflect stubble availability; and the specific re-introduction of stubbles in south-west England for cirl buntings has reversed the population decline of this species. Many of the cornfield flowers are spring germinating and do not appear in winter crops. A range of these plants are also susceptible to herbicides and have been adversely affected by improved seed cleaning techniques, which reduce seed return. Over-wintered stubbles are usually followed by spring cropping, which will encourage many of the rarer cornfield flowers, if they are present in the soil seed bank.

Thus much evidence suggests the loss of stubble may have particularly serious implications for farmland birds. Recognition of this is highlighted by the inclusion of over-wintered cereal and linseed stubbles as an option under the Arable Stewardship Pilot Scheme. Despite their apparent importance, the relative value of different stubble types for plants (particularly arable weeds) and birds is unknown. Stubbles of winter cereals may be rather different to break crops, e.g. legumes, or root or other crops. Straw is usually disposed of by baling or chopping and the seed-containing chaff either spread or left in swaths. The impacts of these operations on arable plants and on seed availability for birds are likely to differ markedly. However, there has been no detailed consideration of the benefits, for plants and birds, of different methods of straw disposal.

Main objective
This project will assess primarily the ecological, and also agronomic, impacts of different stubble types and straw disposal methods by (a) quantifying bird utilisation and foraging; (b) quantifying plant and seed abundance and diversity; (c) relating the results of (a) and (b) to agronomic implications associated with different stubble types and straw disposal methods.

Policy relevance and use of results
The results will provide a strong scientific basis for policy decisions related to current or future agri-environment schemes, notably Arable Stewardship. The research will also assess the practicality to the farmer of the different management options. A particular focus will be on the information needs of MAFF as the lead agency responsible for implementing the UK Biodiversity Action Plans (BAP) for several species associated with farmland. There is a particular need for research on the wintering ecology of many passerines, including BAP species skylark, linnet and tree sparrow. Results from the project should also contribute to the conservation of several Short and Middle List BAP plant species, such as cornflower and small alison.
Objective
1. Quantify seed availability and weed populations on stubbles of different crop types under two herbicide regimes, (i) conventional herbicide treatment and (ii) restricted herbicide treatment.
2. Determine broad utilisation of different stubble crops by birds on a national scale throughout the winter from a survey of birds on farmland overwinter, organised outside this project.
3. Determine detailed utilisation of different stubble crops by birds, in relation to disposal methods and seed abundance, on a local landscape scale throughout the winter.
4. Quantify the pattern of seed availability and vegetation composition and cover on sub-samples of fields within a local landscape through the winter.
5. Quantify the agronomic implications, in relation to the environmental benefits, of the options trialled in Objective1.
6. Provide guidelines for policy decisions related to current or future agri-environment schemes such as Arable Stewardship.
Project Documents
• Final Report : The effects of different crop stubbles and straw disposal methods on wintering birds and arable plants   (8843k)
• Annual Report : The effect of different crop stubbles & cereal straw disposal methods on wintering birds & arable plants   (71k)
• Annual Report : The effect of different crop stubbles & cereal straw disposal methods on wintering birds and arable plants   (4988k)
• Final Report - Annex : The effects of different crop stubbles and straw disposal methods on wintering birds and arable plants   (220k)
• Final Report - Annex : The effects of different crop stubbles and straw disposal methods on wintering birds and arable plants   (56k)
• Final Report - Annex : The effects of different crop stubbles and straw disposal methods on wintering birds and arable plants   (60k)
• Final Report - Annex : The effects of different crop stubbles and straw disposal methods on wintering birds and arable plants   (6166k)
• Final Report - Annex : The effects of different crop stubbles and straw disposal methods on wintering birds and arable plants   (126k)
Time-Scale and Cost
From: 1999

To: 2002

Cost: £208,957
Contractor / Funded Organisations
Rothamsted Research (BBSRC), British Trust For Ornithology
Keywords
Agricultural Land              
Biodiversity              
Environmental Protection              
Land              
Fields of Study
Environmental Stewardship