For a long time, scientists assumed that newly established plants in Europe served less often as food or hosts for native animals and fungi, since they share no common evolutionary history with local fauna and could therefore spread particularly aggressively. According to Staude, the study confirms this initial phase. However, the study also showed that this changes over time: after a few centuries, many of these plants are increasingly used by plant parasites. Unlike pollinators, plant parasites are usually highly specialised in native plants – which makes the findings all the more surprising, according to Staude. "We also observe in this context that the plant parasites interacting with non-native plant species tend, on average, to be more generalist and to exploit a broader range of host plants than those interacting with native species," Staude explains. This means, on the one hand, that nature can adapt to new plants better and faster than previously assumed – but on the other hand, that native plant species are essential for maintaining the high diversity of highly specialised microherbivores.
"Our study is based on a data synthesis in which we combined various sources of information. We had access to a pan-European database documenting over 127,000 interactions between 12,000 plant species and 26,000 microherbivore species. We supplemented this data with additional information about the plants, including their distribution in Europe, time of introduction, geographical origin and relatedness to native species," says Lara Schulte, who conducted the study together with Miriam Wahl as part of their bachelor's theses at Leipzig University. "Using statistical models, we were able to investigate which of these factors determine how strongly non-native plants integrate into ecological networks," adds Wahl.
The findings will make it easier to assess how new plant species become embedded in existing ecosystems. The study shows that ecological networks can adapt over time to changing floras – an important insight for understanding species migration, particularly as climate change progresses. "This knowledge can help to assess the risks posed by non-native species in a more nuanced way. In this way, the study will contribute to adapting conservation and management strategies to a changing species composition," says Staude.
In their research, the scientists examined how many different animals come into contact with non-native plants. They did not investigate which specific types of microherbivores are involved, how severely they damage the plants, or what implications this may have for native species. These questions could help to improve understanding in future of how non-native plants integrate into existing ecosystems.
Original title of the publication in Ecology Letters:
" Non-native plants attain native levels of microherbivory richness with time and range expansion" , DOI: 10.1111/ele.70247
