This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Municipalities are increasingly mowing dikes and verges in stages, so that insects can make longer use of the plants growing there. Mowing is essential to keep a dike strong, explains ecologist Constant Swinkels of Radboud University.
"If you don't mow, trees or sturdy shrubs such as blackberries may start to grow. You don't want that, because their roots are so thick that they can cause dikes to collapse." That is why mowing generally takes place twice a year in the Netherlands. Increasingly, this is done in phases, so that strips of vegetation remain for insects to feed and live in.
However, Swinkels' research shows that this does not work equally well for all insects. "Immediately after mowing, all the insects flock to that strip, and it becomes much busier. There are twice as many flower visits and far more insects, but after four days, they leave the dike and the community collapses completely.
Only strong bees, such as honeybees, remain." Rare species are therefore unable to cope well with partial mowing. For his research, Swinkels and 40 students counted 30,000 flower visits and identified 5,000 wild pollinators down to the species level. They studied dikes in the Ooijpolder near Nijmegen where nothing had been mowed, and a number of dikes where around 70% of the plants had been mowed.
Other dikes were left undisturbed. The paper is published in the journal Insect Conservation and Diversity. The difference between mowed and unmowed dikes was significant.
"Although partial mowing is better than mowing everything, it is not a silver bullet. There are many species that still fly away, even with partial mowing, in search of a safe haven." The solution lies in taking a much broader view, argues the ecologist. "We need to take a landscape-level view of these kinds of problems.
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