Non-native plant species are becoming increasingly common in the streetscapes of Helsinki. For instance, studies in the United States have shown that migratory birds can primarily disperse the seeds of alien plants. To investigate whether this trend holds true in Helsinki, researchers at the University of Helsinki conducted a study on bird-plant interactions. Additionally, in northern regions, rapid climate change is reshaping these interactions.
– As autumns become warmer due to climate change, birds are delaying their migration or becoming more resident in Finland. This, combined with longer fruiting periods for plants, could lead to increased dispersal of alien plants. Moreover, a warmer climate could enable currently benign alien species to become invasive, explains post-doctoral researcher Purabi Deshpande.
The study found that birds are not particularly selective in their choice of fruits in Helsinki, showing no clear preference for native fruits over alien ones. For example, seeds dispersed by blackbirds did not show a higher frequency of native seeds compared to alien seeds. Then again, the study also documented six alien plant species in forest fragments, indicating their spread from streetscapes into more natural habitats – likely facilitated by seed dispersers.
Understanding the interactions between seed dispersers and plants in urban areas is critical for predicting which alien species might become invasive. It also highlights the importance of identifying plants that serve as valuable food sources for urban wildlife. Supporting urban biodiversity can be achieved by planting trees and plants that provide nourishment for animals.
– This research is highly relevant in our increasingly urbanized world, where biotic interactions in cities greatly influence surrounding natural areas, Deshpande concludes.
Original Article:
Research group:
Postdoctoral Researcher Purabi Deshpande, purabi.deshpande@utu.fi
Dr. Edward Kluen