What’s Nibbling On Iceland’s Forests?

Tree growth in Iceland has risen almost exponentially in the last few decades. In part due rather unfortunately to rising temperatures, but also because of proactive reforestation efforts. Taller trees and thicker forests are good for the environment and create new living spaces for animals that couldn’t establish themselves in Iceland before. And yes, that includes bugs. But with the rapid increase in new creepy crawlies, Mother Nature might have some trouble keeping up with the demand. We went to Dr. Brynja Hrafnkelsdóttir of the Icelandic Forest Service Skógræktin to learn more about what’s eating the forests.

Photo by Art Bicnick

“We have plenty of pests. Maybe not as much as in the south of the world, but a lot of them are coming because of global warming,” Brynja explains. “Some of them are also causing more damage than in other countries because they’re new here and there’s a lack of natural enemies.” The lack of predators, such as certain species birds or wasps, makes Icelandic greenery something of an all you can eat buffet for incoming insects.

Recent field research conducted by Brynja and Skógræktin has drawn attention to browning birch tree leaves, as they are being eaten from the inside by two to three newly discovered (in Iceland) species of insects: Scolioneura betuleti or sawflies (birkiþéla in Icelandic), Heringocrania unimaculella or British leafminers (birkikemba in Icelandic), and Fenusella Nana, another sawfly that does not have an Icelandic name yet. All so-called leafminers. Another new pest is the Phratora vitellinae aka brassy leaf beetle or asparglytta in Icelandic, which can be rather aggressive. One of the new natural enemies that have been found, though, is the Carabus nemoralis or bronze carabid (varmasmiður), a big beetle that eats snail eggs or even whole snails.

Apart from that, Icelandic forests still have to deal with larvae of many moth species that do a lot of damage, as well as sap-sucking aphids (aka plant louse). Plus, the research shows that not only are new bugs coming faster and having an easier time establishing themselves due to global warming, already native bugs are changing and spreading northward too, which could overwhelm the local flora.

“Birch is the only native tree species that forms forests here,” Brynja says. “We don’t have many native tree species, like in other countries, and we are a little bit worried about more and more pests coming in, for example on imported tree species or plants. It’s not legal to import tree species in soil but some bugs could come in when they are still in their pupae stage in soil that can come with other plant species that are commonly sold in regular plant shops.”

“There’s some imbalance here. The trees are also not used to it,” Brynja explains. “We’re looking into whether we can potentially import some natural enemies of these bugs. We could work with people in Switzerland for instance who have done this before, with biological controls etc. They would maybe collect natural enemies of the same species there but I don’t know if that will happen.” The importing process is, of course, a lot more complicated than stuffing a bunch of wasps in a box and putting a stamp on it. Though that would also prove difficult and not entirely painless.

“What works quite well is introducing species in greenhouses here, though introducing them to the natural environment is a lot trickier and needs to be handled carefully.” Not to mention that Iceland is known for being rather strict when it comes to any animal coming into or leaving the country (except fish, maybe). But it still beats using insecticides, Brynja says, as that would also just kill whatever natural predator might be trying to establish itself.