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Doctoral thesis, 2013

Occurrence patterns of dead wood and wood-dependent lichens in managed boreal forest landscapes

Svensson, Måns

Abstract

Dead wood is a key resource for biodiversity, on which thousands of forest organisms are dependent. Because of current forest management, there has been a large-scale change in dead wood amounts and qualities, and consequently, many wood-dependent species are threatened. The general aim of this thesis is to increase our understanding of habitat requirements and occurrence patterns of wood-dependent lichens in managed, boreal forest landscapes. We surveyed dead wood and wood-dependent lichens in three study landscapes of managed boreal forest in southern Sweden. The observed occurrence patterns of dead wood in the studied landscapes are to a large extent attributable to management practices, with clear-felling as the main driver of dead wood input. Harvesting forest biomass for bio-fuel production will cause wood-dependent lichens species to decline. Coarse woody debris is important for wood-dependent lichens, but stumps, snags and logs host different species assemblages. Snags are rare in managed forest landscapes and increasing the landscape-scale amount of them would benefit wood-dependent lichens. The previously neglected dead wood type of dead branches on living trees make up a large portion of all dead wood available to wood-dependent species in managed boreal forests. Fine woody debris, including both branches on the ground and dead branches attached to living trees, was, however, found to have a low relative importance for wood-dependent lichens. We modeled species abundance in relation to characteristics of dead wood objects and forest stands, and estimated the landscape-scale abundance of wood-dependent lichens. Young managed forests <60 years of age held the largest populations of these species, because such stands contain more coarse woody debris per hectare than older forests or forested mires, and they occupy a much larger total area. Keeping parts of the landscape outside the forestry system is probably necessary to maintain the landscape-scale persistence of dead wood types that are rarely created within standard management regimes. To conserve the most threatened wood-dependent species, it is necessary to find ways to create and maintain dead wood types and qualities that are currently rare in managed boreal forest landscapes.

Keywords

biodiversity; bio-fuel harvest; coarse woody debris; fine woody debris; habitat requirements; lignicolous; mycobiont; photobiont; saproxylic

Published in

Acta Universitatis Agriculturae Sueciae
2013, number: 2013:84
ISBN: 978-91-576-7906-2, eISBN: 978-91-576-7906-9
Publisher: Department of Ecology, Swedish University of Agricultural Sciences

Authors' information

Svensson, Måns
Swedish University of Agricultural Sciences, Department of Ecology

UKÄ Subject classification

Forest Science
Ecology

URI (permanent link to this page)

https://res.slu.se/id/publ/51860