New arthropod herbivores on trees and shrubs in iceland and changes in pest dynamics: A review

This paper is a review of the history of the introduction of arthropod herbivore species to Iceland since the beginning of the 20^th century. A total of 27 new arthropod herbivore species on trees and shrubs have become established in Iceland during this period. One of the introduced pest species, the pine woolly aphid, has been considered to be the major cause of the almost total eradication of the introduced Scots pine in Iceland. The rate of introduction was found to be highest during warm periods. Outbreaks of pests in birch woodlands were also found to be most severe during warm periods. Other pest species have shown changes in outbreak patterns since 1990. The consequences of these findings for isolated native forest ecosystems and a growing forest resource in Iceland are discussed.