Impact of Heracleum species on bird communities in forested areas
Heracleum mantegazzianum (Apiaceae: EPPO List of Invasive Alien Plants) and H. sosnowskyi (EPPO A2 List) (Apiaceae) are invasive in managed and unmanaged ecosystems in the EPPO region, being a threat to biodiversity, eroding riverbanks, decreasing recreational resources, causing economic losses, and posing a health risk to humans as the sap can cause skin blistering on contact. H. mantegazzianum is native to the Western Greater Caucasus (Russia, Georgia) and H. sosnowskyi is native to the Eastern and Central Caucasus, Eastern and Southern Western Transcaucasia, and Northeast Anatolia (Turkey). Due to their large size (up to 3 m in height), these plants can threaten bird species living in forest stands by changing the structural diversity of below canopy vegetation. A study was conducted in areas invaded by the two species in forest communities in the south-east of Poland. The study set out to assess if the invasion of the two Heracleum species affects bird species composition and diversity. The forest bird community was estimated in 38 sites with varying levels of invasion and compared to similar habitats that were uninvaded. Bird surveys were conducted five times at each site during 2020-2021. All birds that were seen and heard were included in the survey. In total, 69 species of birds including 1 366 individuals were recorded from control sites and 65 species of birds including 1 065 individuals were recorded from Heracleum sites. The negative effect of Heracleum spp. on the abundance of forest birds was more important in severely invaded areas with anthropogenic habitats. Surveyed bird communities had a lower diversity in invaded sites compared to the control, with 895 forest birds and 471 non-forest birds on control sites, compared to 713 forest birds and 352 non-forest birds on Heracleum sites. The study highlights that invasive alien plant species can cause negative impacts at a community level and the impacts can reach higher trophic levels.
Sources
Grzedzicka E (2022) Impact of invasive weeds on the diversity and dissimilarity of bird communities in forested areas. Diversity 14, 229. https://doi.org/10.3390/d14030229