The short-term effects of wildfire on heathland flowering plant communities as a resource for insect pollinators: a case study at Killarney National Park, Ireland

Thomas Robert Howells , Kilian Kelly, Aifionn S. Evans, Eoghan Phelan, Patrick Gleeson, Christina Maloney, Domonkos Boka, Alannah Warren, Rachel Dowling, Siún Ní Cheallaigh, Jaimie Maidwell, Joanne Monaghan, Darren M. Evans

Fire is a globally important driver of ecosystem diversity and functioning, yet the frequency and behaviour of wildfire has become increasingly unpredictable as a result of climate change, posing risks to ecosystems, societies, and economies. Post-fire plant and animal community dynamics are often shaped by ecological, landscape, and fire characteristics, but as risk factors change, understanding community responses, rather than individual species, is critical for predicting post-fire trajectories and informing management.

Temperate heathlands are of cultural, ecological, and economic importance in Europe but face heightened wildfire risk due to changing land management and climate. In April 2021, a wildfire burned extensive areas of mixed heathland within Killarney National Park, Ireland. Here, we used a paired burnt–unburnt experimental design to quantify the effects of this event on floral community composition and the availability of food resources for pollinating insects in heathland habitats.

Results demonstrated a decrease in the number of insect pollinated flowers (floral units) during the first year post-fire, despite an overall floral unit increase driven by certain wind-pollinated species. However the effects became weaker two years post-fire, with increased compositional similarity between Fire and Control communities and an increase in insect-pollinated floral units, although responses varied seasonally. Some species occurred more frequently in Fire or Control sites, indicating distinct post-fire “winners” and “losers”. While there is evidence of post-fire floral recovery, proportional increases in certain fire-favouring species suggest potential shifts in community structure and resource availability for pollinators following wildfire. This has implications for the resilience of this landscape under altered fire-regimes and potential cascading effects on pollination services.