What type of landscape is best for pollinators?
SINCE the Second World War, advances in machinery, widespread use of chemicals such as pesticides, genetic research and new agricultural policies have led to more intensive farming.
So, over the years, the agricultural environment has undergone substantial change as humans have reshaped the landscape according to their needs.
For instance, modern agriculture promotes a small number of highyielding crop species, which dominate the landscape: flower-rich grasslands have been converted to crop fields and fields have become larger with the removal of hedgerows to make the harvest easier and quicker.
The landscape is a complex structure, characterised by its configuration and composition – in other words the size and shape of a particular area and the purpose for which it is used, such as arable crop, grassland, lake, hedgerow, stone wall or building.
But, has the changing landscape structure influenced the diversity of flower-visiting insects, which provide important pollination services to plants?
Pollinators are mobile and dependent on the availability of flowers, nest sites and overwintering sites in the landscape to meet their needs.
Each pollinator species has its own specific needs and does not find food in the same range of plants as another pollinator species. Nor does one pollinator species need the same site for overwintering and nesting as another.
Through our research, we are trying to investigate what landscape structure is the best for the overall pollinator community, but also for each pollinator group, such as the bumblebee, butterfly solitary bee and hoverfly.
We know that a landscape with a higher proportion of flower-rich grasslands has a favourable impact on the overall pollinator community. These grasslands harbour a high diversity of plant species and so cover a wider range of resources for pollinators.
A landscape with a higher number of stonewalls may be beneficial for bumblebees as pollinators might find nest sites under walls.
We have also seen that the size and shape of patches of habitat in the landscape is important also for pollinators. In extensive agricultural landscapes, the shape and size of particular elements are less regular than in systems designed for intensive farming and this is good for pollinators.
In our research, we are gathering data in different types of habitat and different areas of Ireland to provide an overview of how different landscapes affect pollination. For instance, could even the length of a stretch of hedgerow be important?
Our research will allow us to determine conservation measures for different pollinating insects and to recommend strategies to promote pollination of both crop and wild plants in agricultural landscapes.