Individual study: Uncropped, cultivated margins and conservation headlands without fertilizer are the best options for conservation of arable plant in field margins in the UK
Critchley C.N.R., Walker K.J. & Pywell R.F. (2007) The contribution of English agri-environment schemes to botanical diversity in arable field margins. Aspects of Applied Biology, 81, 293-300
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Leave cultivated, uncropped margins or plots (includes 'lapwing plots')
A replicated site comparison study in the UK (Critchley et al. 2007) found that uncropped, cultivated margins had more plant species than other field margin types, and increased plant species richness over time in one (but not all) areas. In a national survey of field margins under the Countryside Stewardship Scheme, 39 uncropped regularly cultivated field margins had more plant species (31 species/margin) than 72 control margins (8 species/margin) and 78 conservation headlands (11-17). Thirty-nine margins that were uncropped and cultivated for one year (called ‘spring fallow’) had 20 plant species on average. In the pilot Arable Stewardship Scheme in two English regions (East Anglia and the West Midlands), 24 uncropped cultivated strips had greater numbers of perennial plants and pernicious weeds after four years (measured in 1999 and 2003), but the total number of species did not increase (7-8 plant species/margin). By contrast, there was a substantial increase in number of plant species in 32 uncropped cultivated margins in the Brecklands Environmentally Sensitive Area (ESA) between 1996 (12 species/margin) and 2004 (18 species/margin). Here the number of pernicious weed species did not increase. Plants were surveyed in either thirty 0.025 m2 quadrats within a 100 m sampling zone or twenty 10 x 10 cm quadrats (only used in Brecklands ESA). Percentage cover and plant species were recorded in each quadrat.
Plant wild bird seed or cover mixture
A replicated site comparison study in 1999 and 2003 in the UK (Critchley et al. 2007) found that 33 field margins sown with a locally specific ‘wildlife seed mixture’ had greater numbers of perennial plants and pernicious weeds after four years, but the total number of plant species did not increase (7-8 plant species/margin). This option was not considered the best option for the conservation of arable plants. The most commonly sown plant species were brassicas (sown at 14 sites). Cereals, maize Zea mays, buckwheat Fagopyron esculentum, borage Borago officinalis, grasses, legumes, teasel Dipsacus fullonum and phacelia Phacelia tanacetifolia were also sown at some sites. Plants were surveyed in thirty 0.025 m2 quadrats within a 100 m sampling zone. Percentage cover and plant species were recorded.
Plant grass buffer strips/margins around arable or pasture fields
A replicated site comparison study in the UK (Critchley et al. 2007) found that sown grassy margins more than two years old had 87-95% cover with grasses. Those sown with wildflowers had on average 28% cover with non-grass broadleaved plants, compared to 14% cover in margins sown with a simple grass seed mix. This option was not considered the best option for conservation of arable plants. A total of 75 sown grass margins were surveyed in 2004. Twenty-two of them were sown with some non-grass flowering species, as well as grasses. Margins were randomly selected from eight UK regions. Plants were surveyed in thirty 0.025 m2 quadrats within a 100 m sampling zone of each margin and percentage cover across all quadrats estimated. This study was part of the same experimental set-up as (Critchley et al. 2006).
Leave headlands in fields unsprayed (conservation headlands)
A replicated site comparison study in 2004 and 2005 in the UK (Critchley et al. 2007) found that conservation headlands without fertilizer had more plant species (17 species/margin) than standard conservation headlands (reduced pesticide only, 11 species/margin) and significantly more species than control margins in all plant groups except grasses. Standard conservation headlands did not have significantly more plant species than control margins (11 and 8 species/margin on average), but they did have a higher percentage of spring germinating plant species (63% of plant species were spring germinating, compared to 48% in control margins). Thirty-nine of each type of conservation headland managed under the Countryside Stewardship Scheme, were surveyed in 2005, and compared with 72 conventionally cropped field margins surveyed in 2004 or 2005. Margins were randomly selected from eight UK regions. Plants were surveyed in thirty 0.025 m2 quadrats within a 100 m sampling zone of each margin and percentage cover across all quadrats estimated.