Quantifying climate impacts and biodiversity effects of increased forest biomass harvests – an integrated assessment

Abstract

Increasing forest biomass harvests to combat climate change by replacing fossil fuels with bioenergy may pose a trade-off with climate regulation services of forests and biodiversity conservation. Previous forest bioenergy studies focus mainly, either on effects on carbon cycle or biodiversity impacts (1–3). These studies show that increased extraction of branches, stumps and other residual biomass from current levels decreases the carbon stock and the carbon sink capacity of forests, and has negative effects on species depended on deadwood. Nevertheless, still little is known how climate regulation services or biodiversity indicators respond to a large scale removal of harvest residues in the long term, and at the landscape level. We provide an integrated, dynamic, assessment to quantify the effects of forest residue harvesting on forest carbon balance and biodiversity in boreal forest landscapes. Through a modeling framework we simulated forest development in four real watersheds located in central Finland with three scenarios: i) with and ii) without forest residue harvesting for bioenergy, and iii) set aside to study the conservation potential of these landscapes in the future without management. We simulated changes in the forest carbon stocks and the quality and quantity of deadwood resources for 100 years, and combined this information with the information of species habitat associations based on expert judgments. This study reveals how extensive forest harvest residue extraction for bioenergy affects forest carbon balance and the availability of suitable habitats for red-listed, saproxylic species. Furthermore, the results indicate a conflict between areas of high bioenergy potential and high conservation potential. We also discuss whether current recommendations for energy wood harvesting encourage to the least harmful harvesting practices. The findings of this study can be used in developing guidelines, practices and criteria to ensure the sustainability of forest bioenergy. The work is part of the Sumforest project FutureBioEcon.

References 1. Schulze, E.-D., Körner, C., Law, B. E., Haberl, H. & Luyssaert, S. Large-scale bioenergy from additional harvest of forest biomass is neither sustainable nor greenhouse gas neutral. GCB Bioenergy 4, 611–616 (2012). 2. Bouget, C., Lassauce, A. & Jonsell, M. Effects of fuelwood harvesting on biodiversity — a review focused on the situation in Europe. Canadian Journal of Forest Research 42: 1421-1432 (2012). 3. Riffell, S., Verschuyl, J., Miller, D. & Wigley, T. B. Biofuel harvests, coarse woody debris, and biodiversity – A meta-analysis. For. Ecol. Manage. 261, 878–887 (2011).