Barton Fields Review - 2011

Yellow Rattle restricts growth of tall grasses

For the last two years we have surveyed the newly established wildflower meadow, recording all the flowering plants and grasses in one metre square quadrats.This year, despite the weird weather pattern, an estimated 5400 flowering plants were recorded in the 47 quadrats we surveyed, an increase of 96% over 2010. Fifty flowering plant species were recorded in the meadow this year, of which 22 were introduced by seeding or planting in 2009. It is very encouraging that some of the introduced species such as Bird's-foot Trefoil, Knapweed and Lady's Bedstraw are now widespread and doing well. Yellow Rattle, the annual,semi-parasitic plant is easily the most common plant in the field having increased each year since it was sown in 2008. This has had a dramatic effect in reducing the vigour of grasses, allowing herb species to thrive and increase.

A group of us take turns in doing weekly butterfly transect in Barton Fields and also in the Radley Lakes area. In Barton Fields 888 butterflies were record this year, including two species new to our list: Grizzled Skipper and Small Blue. The tiny Grizzled Skipper had not been observed in this part of Oxfordshire for about 30 years but was photographed at Radley Lakes for the first time this Spring. It was recorded later in Barton Fields by three people. The single Small Blue recorded by Adrian Allsop, is Britain's smallest butterfly.
The wildflower meadow is particularly good for butterflies, particularly Meadow Brown, Gatekeeper, Common Blues and Brown Argus. In fact the number of butterflies recorded per 100 metres was 2.8 times higher than the number in an adjacent un-enhanced area of the field. These insects benefit from the provision of food plants for their caterpillars, the flowers providing nectar, and the low  vegetation and sparse grass cover which creates a warm microclimate.

We have continued with the introduction of native plant species. This year we have planted two patches of Kidney Vetch in sunny sheltered positions and also a number of areas planted with Viper's Bugloss. Kidney Vetch is the food plant of the Small Blue butterfly, which we are hoping to attracting as a breeding species. It is encouraging that one insect was recorded this year, though we do not know where it came from. This year's low rainfall has lowered the water table and some of our groundwater fed ponds dried out. We took the opportunity to dig these out further and have been rewarded by seeing frogs, toads and egg laying dragonflies in the clear water of these deepened ponds.