Transient trade‐off between climate benefit and biodiversity loss of harvesting stumps for bioenergy

• Published in: Global change biology. Bioenergy 2017-12, Vol.9 (12), p.1751-1763
• Main Authors: Snäll, Tord, Johansson, Victor, Jönsson, Mari, Ortiz, Carina, Hammar, Torun, Caruso, Alexandro, Svensson, Måns, Stendahl, Johan
• Format: Article
• Language: English
• Subjects: Biodiversity; Biodiversity loss; Clearcutting; Climate; Climate change; Climate change mitigation; Coal; Coarsening; Colonization; Cooling effects; Dead wood; deadwood; Ecology; Ekologi; epixylic lichens; Forest management; Fossil fuels; Global temperatures; harvest residues; Harvesting; Landscape; Lichens; Life cycle analysis; life cycle assessment; Life cycle engineering; Life cycles; metapopulation dynamics; Metapopulations; net global temperature change; Reduction; Renewable energy; Species extinction; Temperature effects; Tradeoffs
• ISSN: 1757-1693; 1757-1707; 1757-1707
• DOI: 10.1111/gcbb.12467

To replace fossil fuel and thereby mitigate climate change, harvesting of wood such as stumps for bioenergy will likely increase. Coarse deadwood is an important resource for biodiversity and stumps comprise the main part of the coarse deadwood in managed forests. We provide the first integrated analysis of the long‐term climate and biodiversity impacts of a whole landscape. We simultaneously project climate and biodiversity impacts of harvesting stumps to substitute for fossil coal, assuming scenarios with different proportions of the landscape with stump harvest (10, 50, 80%) the coming 50 years. A life cycle approach was used to calculate future global temperature changes and future metapopulation changes in six epixylic lichens. Metapopulation dynamics were projected using colonization and extinction models based on times series data. Harvesting stumps from ≥50% of the clear‐cut forest land benefits climate with a net global temperature reduction >0.5·10−9 K ha−1 after 50 years if assuming substitution of fossil coal. For all scenarios, using stump bioenergy leads to immediate (within 1 year) reductions in temperature of 50% compared to using fossil coal, increasing to 70% reduction after 50 years. However, large‐scale stump harvest inflicted substantial metapopulation declines for five of six lichens. High stump harvest levels (≥50%) put common lichens at risk of becoming red‐listed following the IUCN criteria. The net temperature reduction (cooling effect) from substituting fossil coal with stumps harvested for bioenergy increased over time, while lichen metapopulations stabilized at lower equilibria after two to three decades. This indicates that trade‐offs between climate and metapopulations of commons species are transient, where climate benefits become more prevalent in the long term. As both objectives are important for meeting (inter‐)national climate and biodiversity targets, integrated analyses such as this should be encouraged and urged to guide policymaking about large‐scale implementation of stump harvest. Trade‐offs between increasing climate benefit resulting from increasing the proportion of stands where stumps are harvested and the future metapopulation size of lichen species. The high rates of metapopulation decline suggest that some species may become red‐listed. However, the trade‐offs seem transient, with metapopulations levels reaching new equilibria and climate benefits become more prevalent in the long term.