Relative contributions of set-asides and tree retention to the long-term availability of key forest biodiversity structures at the landscape scale.
Over previous decades new environmental measures have been implemented in forestry. In Fennoscandia, forest management practices were modified to set aside conservation areas and to retain trees at final felling. In this study we simulated the long-term effects of set-aside establishment and tree retention practices on the future availability of large trees and dead wood, two forest structures of documented importance to biodiversity conservation. Using a forest decision support system (Heureka), we projected the amounts of these structures over 200 years in two managed north Swedish landscapes, under management scenarios with and without set-asides and tree retention. In line with common best practice, we simulated set-asides covering 5% of the productive area with priority to older stands, as well as ∼5% green-tree retention (solitary trees and forest patches) including high-stump creation at final felling. We found that only tree retention contributed to substantial increases in the future density of large (DBH ≥35 cm) deciduous trees, while both measures made significant contributions to the availability of large conifers. It took more than half a century to observe stronger increases in the densities of large deciduous trees as an effect of tree retention. The mean landscape-scale volumes of hard dead wood fluctuated widely, but the conservation measures yielded values which were, on average over the entire simulation period, about 2.5 times as high as for scenarios without these measures. While the density of large conifers increased with time in the landscape initially dominated by younger forest, best practice conservation measures did not avert a long-term decrease in large conifer density in the landscape initially comprised of more old forest. Our results highlight the needs to adopt a long temporal perspective and to consider initial landscape conditions when evaluating the large-scale effects of conservation measures on forest biodiversity.
Department of Wildlife, Fish and Environmental Studies, Faculty of Forest Sciences, Swedish University of Agricultural Sciences (SLU), SE-90183 Umeå, Sweden. Electronic address: Jean-Michel.Roberge@slu.se.
Jean-Michel
JM
Roberge
Department of Forest Resource Management, Faculty of Forest Sciences, Swedish University of Agricultural Sciences (SLU), SE-90183 Umeå, Sweden. Electronic address: Tomas.Lamas@slu.se.
Tomas
T
Lämås
Department of Forest Ecology and Management, Faculty of Forest Sciences, Swedish University of Agricultural Sciences (SLU), SE-90183 Umeå, Sweden. Electronic address: Tomas.Lundmark@slu.se.
Tomas
T
Lundmark
Department of Ecology, Faculty of Forest Sciences, Swedish University of Agricultural Sciences (SLU), P.O. Box 7044, SE-75007 Uppsala, Sweden. Electronic address: Thomas.Ranius@slu.se.
Thomas
T
Ranius
Southern Swedish Forest Research Centre, Faculty of Forest Sciences, Swedish University of Agricultural Sciences (SLU), P.O. Box 49, SE-23053 Alnarp, Sweden. Electronic address: Adam.Felton@slu.se.
Adam
A
Felton
Department of Forest Genetics and Plant Physiology, Faculty of Forest Sciences, Swedish University of Agricultural Sciences (SLU), SE-90183 Umeå, Sweden. Electronic address: Annika.Nordin@slu.se.
Annika
A
Nordin
D044822:Biodiversity; D003247:Conservation of Natural Resources; D017753:Ecosystem; D016468:Forestry / Q000379:methods*; D006801:Humans; D013548:Sweden; D014197:Trees; D014934:Wood
Biodiversity conservation; Dead wood; Forest management; Landscape simulations; Large trees; Tree retention