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HELPING YOU TO HELP WILDLIFE ON YOUR FARM |
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Management of grass set-aside for wildlife, East Lothian |
01.11.2005 |
Author: Mike McDowall, Managing Director, Townhead (McDowall) Limited
Farm: No farm specified |
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Aims:
Long term grass set-aside was observed to be yielding limited biodiversity benefits on our East Lothian farm. A typical agricultural grass seed mix had been used, and ryegrasses and cocksfoot continue to dominate the sward. Vole numbers developed to a very healthy level, supporting kestrel, buzzard and presumably owls but plant diversity, on which much biodiversity rests, remained low. While adopting new managements such as not cutting some areas allowed seed production and benefits to more species, notably linnets, plant diversity remained low.
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Management:
At this point the farm became involved in the SAFFIE trial and the issue was discussed with the trial botanist, Dr.Duncan Westbury of Reading University. He suggested power harrowing areas to open up the sward and permit other plant species to become established.
Appropriate approvals were obtained from the Scottish Executive Environment and Rural Affairs Division (now the Scottish Government Rural Payments and Inspectorate Division or SGRPID) who were most helpful. Areas were cultivated in spring in rotation and in combination with a reduced mowing programme to create a mosaic of areas which had different combinations of management ranging from no intervention to both late summer mowing and spring power harrowing.
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Achievements:
Small increases in broadleaved plants were noted. Most of the plants were volunteer oil seed rape. While this was disappointing, probably a reflection of a deprived seed bank following years of arable cultivation combined with effective herbicide, spin off benefits did accrue. The area concerned had been, by this farms standards, unattractive to skylark. The block of set-aside, approximately 4 hectares, and neighbouring arable fields in the block totalling another 22 hectares or so had typically supported one or two singing skylark each year (the same as when the set-aside had been cultivated too). After cultivation the numbers quickly rose to 8 and in later years peak numbers have totalled 30 or so within the block of set- aside. Peaks of this order can be found in both summer and winter.
The cultivation management has been hugely beneficial to skylark.
We have added other managements to this block, notably provision of 1 hectare of wild bird cover without apparent detriment to the skylark, but adding benefit for other seed eating species such as linnet, reed bunting and yellowhammer.
Lessons
The SAFFIE trial results have now been published in the Annals of Applied Biology. As well as providing the evidence for skylark plots in arable fields, this research looked at management of grass/wildflower mix margins using cultivation. It appears that invertebrate productivity is highest in thick swards, but birds reliant on invertebrates for chick food, such as skylark, find foraging difficult. Cultivation of some areas provides the important foraging opportunities. We can now see why our previous efforts had such a benefit for skylark.
We used the research to re-design our management of grass set-aside to employ one three yearly cultivation. Again, SGRPID permission has been readily obtained. The block is cultivated in strips. One third is cultivated each spring, moving progressively across the strip to provide a succession of growth stages. We hope this will provide the stages required for invertebrate production and foraging; continue to provide thick grass habitat for voles; and may over the longer term provide opportunities for development of generally greater diversity.
At the same time cost has been minimized by removing the need for annual mowing (dangerous on our stony soils !) and reducing the area to be cultivated to one third of the block annually. We intend to review this after three years with a view to extending the rotation further.
While this management has been carried out on set-aside, it should be appropriate for any block of unproductive improved grassland.
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July 2009 update
Further experience has shown that the 3 year regime is definitely too short, endangering vole populations as the most suitable habitat is the area cultivated. The rotation will definitely need to be lengthened and modified to avoid cultivating too much of the best habitat at one time. |
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| Images ©RSPB, except Greater Horseshoe Bat ©Bat Conservation Trust |
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