Biologist: The effects of the warm year on nature become clearly visible

It is a very warm year and this autumn also affects nature, observes biologist Arnold van Vliet of Wageningen University & Research (WUR). For example, trees stay green longer and the notorious hay fever plant wormwood has longer to multiply. "The changes in nature are spectacular," Van Vliet says.

The biologist also notes that some insects remain active longer. "When I ride my bike after work, I see a wasp nest that is still in full swing now. This is despite the fact that it's already early October," he says. "Normally, the new queens would have fledged by now and would be looking for a place to hibernate." De Vlinderstichting also recently reported that some butterfly species are reproducing more frequently each year. Because it's warm, they have time for an extra generation.

"This can become a problem if there is not enough food for all these insects," Van Vliet says. Roadsides are often mowed in preparation for fall and winter. Then the insects can no longer find flowers and nectar, and there are fewer places to hide. "Municipalities should leave more spots unmown now that it's staying warm longer," the biologist says.

Another problem, according to Van Vliet, is that as long as it stays warm, aphids fly around longer. "In the process, they spread all kinds of plant viruses, including viruses to which potatoes are vulnerable." Until August, aphids are monitored by the Dutch General Inspection Service (NAK), but "given climate change, this should be monitored longer."

All in all, Van Vliet sees that a "massive shift" is taking place in nature due to the world becoming warmer. "Plants and animals are slowly shifting to cooler areas in the north, and as a result, their habitat is generally getting smaller. So the pressure on species is increasing, and that makes them vulnerable to all kinds of factors. Also, it takes a long time for plants and animals to move, which sometimes results in species being in poor condition.