The birds and the bees

Hedgerow fruit such as sloes and hawthorn berries are an important winter food for many birds and other wildlife, and are also appreciated by people as a form of wild food. 

Abundance of pollinating insects has declined on farmland over past decades, but little is known about the effect this may have on fruit set by hedgerow shrubs. 

This PhD project, carried out by Jenny Jacobs at Loddington and Rothamsted, explores this issue.  As well as the influence of pollinating insect species and abundance on fruit set, the project also investigates the effect of hedgerow orientation and the proximity of flowering crops such as oilseed rape. 

For example, if there is an increase in the area of oilseed rape grown in response to demand for biofuels, will this influence the numbers of pollinating insects in hedges, and subsequently the fruit set, or will those insects be drawn away from the hedge by the crop?

Initial findings suggest that, while the abundance of pollinating insects has no effect on fruit set of some hedgerow species, for blackthorn and hawthorn there is a very considerable effect.  This was particularly the case for blackthorn.  Fruit set was higher on warm (south-facing) hedges than cooler ones, possibly reflecting greater insect activity on the warmer hedges.  Initial results suggest that there is no effect of adjacent crop on hawthorn fruit set.