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This larvae destroyed 10.000 km² of forest

Larvae of birch moth is a common sight in the forests of the northern parts of Norway, Sweden and Finland.

One third of all the birch forest in Northern Fennoscandia has been ruined by moth larvae in the period 2002-2009. Climate change brings new types of pest insects to the Arctic region.

Location

10.000 square kilometers of the birch forest in the northern parts of Norway, Sweden and Finland has been destroyed by moth larvae since 2002. Huge areas of forest have been left brown and leafless and it can take decades before new trees have grown up to replace the dead ones.

The birch forest in the north has from time to time during the centuries been attacked by outbreaks of the Autumnal Moth (Epirrita autumnata). The larvae eat shoots and leaves. After the attacks the forest is brown and is badly shaken, but most of the trees have survived. But now two other moths have moved in from the south and occupied a place in the northern ecosystem next to the Autumnal Moth, scientists say.

During the large outbreak in 2002 it was the Autumnal Moth that first attacked the forest. In many areas the Winter Moth (Operopthera brumata) had an outbreak only one or two years later. “The forest being attacked by two different species consecutively, made the attack last longer and the impact on the forest more severe than in earlier attacks”, Jane U. Jepsen at NINA (Norwegian Institute for Nature Resarch) says to forskning.no. “In the last years we have also seen that the Scarce Umber (Agriopis aurantiaria) has reached northern Norway. This species has settled in large parts of the coastline, but has so far only resulted in local outbreaks.

“A birch tree can survive even if it loses all leaves, but it will not survive it it happends year after year,” Jepsen says to Aftenposten. “Our birch has adapted to the normal, short attacks of larvae, but repeated attacks by different species will give the forest serious problems.”

Changes flora and fauna
The moth larvae outbreaks result in changes in the rest of the flora and fauna in the forest. Heather gives way to grass, while reindeer give way to mouse and lemming, forskning.no reads.