title: The influence of ants on the survival of mountain birches during an Oporinia autumnata (Lep., Geometridae) outbreak.
abstract: The present study reports the influence of ants on the survival of mountain birch (Betula pubescens ssp. tortuosa) during an Oporinia autumnata (Lep., Geometridae) outbreak. Undamaged "green islands" with a radius of 15-20 m were observed around Formica aquilonia mounds in a defoliated area in Finnish Lapland. The herbivore densities and grazing pressure were shown to be low within this radius. The foraging strategy of ants and their influence on birch growth are discussed.
authors.affiliation: Department of Biology, University of Turku, SF-20500, Turku 50.
authors.forename: Kari J
authors.initials: KJ
authors.lastname: Laine
authors.affiliation: Department of Biomedicine/Zoology, University of Turku, SF-20500, Turku 50, Finland.
authors.forename: Pekka
authors.initials: P
authors.lastname: Niemelä