Insects contribute to ecosystem services by pollinating crops, but their populations have been declining for years. The new study, published in Science, shows that changing the management of existing semi-natural habitats – such as hedgerows, small woodlands, and extensively managed grasslands – helps reduce pollinator loss by improving quality. However, increasing the area of these habitats can be just as, or even more, effective.
“The study highlights the benefits of preserving and expanding the amount of habitat with flowering plants in agricultural landscapes, such as hedges, field margins and pastures,” says Henrik Smith, professor at CEC and the Department of Biology and one of the researchers behind the study.
Current targets
The EU’s biodiversity strategy aims to reintroduce landscape elements with high biodiversity on 10% of agricultural land. The current study, based on data from 59 studies worldwide, shows that pollinators benefit most when the amount of these habitats is increased to between 16% and 37% of the agricultural landscape, depending on the species group. Beyond these percentages, improving the quality of existing habitats becomes more effective.
“In intensively farmed areas, the proportion of semi-natural habitats is small, often just a few percent, so there is great potential to increase habitat area – and of course preferably of good quality,” says Maj Rundlöf, associate professor at the Department of Biology, who also contributed to the study.
Area and Quality Must Increase
The study examined how the area and quality of semi-natural habitats affect populations of wild bees, bumblebees, hoverflies, and butterflies. For all species groups, one simple rule applied: the more flower-rich habitats, the more pollinators in the agricultural landscape. Habitats with more flowering plants did host more pollinators than areas with few flowers, but the study’s results show that increasing the total area of semi-natural habitats may have a greater impact than improving management alone.
“However, it’s important to note that many individual species have high demands on their habitats, which means that quality is also important,” says Henrik Smith.
Long-Term Commitment from Farmers
Pollinator conservation in Europe largely focuses on temporary measures on small parts of productive land, such as flower strips along fields. Previous research has shown that this can lead to an increase in insects and pollinators, especially if the measures are ongoing for several years. The new study shows that expanding the area of such habitats is an effective way to reverse negative trends for pollinators.
“To truly make a difference, it should be possible to reward farmers for creating and maintaining new semi-natural habitats on their farms in the long term. Through long-term commitments, farmers can gain sufficient security while also benefiting pollinators,” says Henrik Smith.
Politically Relevant
There is growing evidence that biodiversity is important – not just for nature, but also for people. Pollinators, for example, are beneficial for the production of many crops we depend on. The recently adopted EU regulation on nature restoration therefore aims to halt biodiversity loss in general and pollinator decline in particular. Restoring or protecting semi-natural habitats in agricultural landscapes is a key tool in that strategy. EU member states are currently developing concrete action plans for how this will be achieved.