Decade of dataset provides key clues to support Ireland’s valuable pollinators

Ecologists from Trinity College Dublin have found important clues about how we can best support Ireland’s precious pollinators after querying a ten-year dataset containing information from 119 sites across the country.

Overall, the results confirm the importance of plant (and thus floral) diversity in supporting a hodgepodge of pollinating species, and while they underscore the invaluable role of bumblebees, they also shed light on the importance of other species – including hoverflies especially more frequent as flower visitors than expected.

The dataset contains detailed plant-pollinator interaction data from sites across Ireland across habitat types such as built and developed land; coastal areas; semi-natural and swampy grassland; hedges; and forests and scrub.

It has grown and grown over the past decade thanks to the work of Trinity Professor Jane Stout and her staff, with much work by PhD students supported by the Environmental Protection Agency, Irish Research Council, Trinity and EU sources.

The six key findings from research recently published in the journal ecology and evolutionare:

• More flowers = more insect pollinators, regardless of habitat
• Flies are underrated in their posts; half of all flower visitor species were hoverflies, and these species account for over 33% of all visits
• Rich, widespread floral species such as bramble, white clover, knapweed and creeping buttercup are visited by many insects, but rare plants are important to rare pollinators
• Natural meadows are particularly important; They had the most pollinator species and visits, and the communities were the most ‘distinct’, meaning they differed from other sites and contained the rarest species
• Bumblebees are a central part of Ireland’s pollinator fauna
• Intensively managed habitats (urban, crop and silage/dairy) have low pollinator diversity, despite abundant ornamental plants in urban areas

The researchers behind the work — led by Professor Stout and Laura Russo, now a professor of ecology and evolution at the University of Tennessee Knoxville — hope these findings can be used to guide conservation and land management practices in key areas.

Jane Stout, Vice President for Biodiversity & Climate Action Sustainability and Professor of Botany at Trinity College, said: “One of the key conclusions from this work is that Irish semi-natural grasslands are essential for the protection of pollinators of most species, including the rarer species , which do not occur in more heavily managed habitat types, and a higher proportion of threatened bee species, but also a lower proportion of non-native plant species, are also important for the protection of native plants.

“Given that most of Ireland is covered by heavily managed habitats such as agricultural crops, silage and dairy pastures, and urban and suburban gardens and flower beds, it is worrying that these habitats supported relatively fewer insect species. Urban habitats had more non-native plant species, which is not surprising given that most garden plants are not native to Ireland. But this increase in non-native plant species has not matched an increase in insect diversity. How native plant diversity has been brought back to our highly managed land Habitats is important to supporting pollinator communities and represents a measure thousands of us can take fairly easily to increase pollinator numbers.

This work feeds into the All-Ireland Pollinator Plan, which aims to provide food, shelter and security for bees and other pollinators in Ireland so they can survive and thrive.