Does snail grazing affect growth of the old forest lichen Lobaria pulmonaria?

Grazing marks from snails are frequently observed in populations of the old forest epiphyte Lobaria pulmonaria. However, grazing marks are more numerous in thalli from deciduous broadleaved forests than in thalli from boreal Picea abies forests, due to higher populations of lichen-feeding molluscs in deciduous stands. Here we tested for deleterious effects of snails on the lichens by transplanting 600 more or less grazed L. pulmonaria thalli from deciduous forests to snail-free P. abies forests. Subsequent measurements showed that growth rates were as high in thalli with many grazing marks as those without, suggesting that growth of mature lobes of L. pulmonaria are not inhibited by the recorded grazing pressure imposed by lichen feeding snails.