Authors: Hämäläinen, Aino; Fahrig, Lenore;Strengbom, Joachim;Ranius, Thomas;

Habitat loss is a major threat for biodiversity, but the scales on which its effects occur are poorly understood: is the amount of available habitat important for species occurrence on both local and landscape scale? Recognizing the correct scale is critical for successful nature conservation. We studied the importance of local and landscape-scale habitat amount for deadwood-dwelling lichens in Swedish boreal forests. We surveyed lichen assemblages in 90 forest stands that differed in the local (stand-scale) dead wood amount, and in the landscape-scale habitat amount (estimated as the amount of dead wood or old-growth forests, on scales 300 m – 5 km). Lichen species density increased with the landscape-scale, but not with the local habitat amount, whereas species composition was not affected by the habitat amount on any scale. The best measure for landscape-scale habitat amount was the proportion of old (> 100 years) forests on 5 km scale. The results indicate that to benefit the studied species, the amount of old forests in managed forest landscapes should be increased and dead wood restoration or retention should be directed to landscapes with a higher proportion of old forest. Increasing only the local dead wood amount would not benefit the species.