TemaNord 2013:507 TemaNord Ved Stranden 18 DK-1061 Copenhagen K www.norden.org Biodiversity, carbon storage and dynamics of old northern forests Biodiversity, carbon storage and dynamics of old northern forests Forests play a key role in the global climate system. The Nordic countri- es have extensive forests with large and growing tree biomass that captures substantial amounts of the greenhouse gas carbon dioxide. Nordic forests are also important for biodiversity, with complex eco- systems providing habitats for about half of all known native species and threatened species in Finland, Norway, and Sweden. Forests also supply the basis for the economically important forest sector. In this report we review current knowledge on the role of old forests in the carbon cycle, their natural dynamics and importance for biodiversity. Based on evidence in the literature, it is clear that old forests continue to accumulate carbon for a long time, well past the normal logging age. The carbon uptake of old forests represents an important co-benefit for the well-documented value of old forests for biodiversity. TemaNord 2013:507 ISBN 978-92-893-2510-3 TN2013507 omslag.indd 1 24-01-2013 11:18:04 Biodiversity, carbon storage and dynamics of old northern forests Erik Framstad, Heleen de Wit, Raisa Mäkipää, Markku Larjavaara, Lars Vesterdal and Erik Karltun TemaNord 2013:507 Biodiversity, carbon storage and dynamics of old northern forests Erik Framstad, Heleen de Wit, Raisa Mäkipää, Markku Larjavaara, Lars Vesterdal and Erik Karltun ISBN 978-92-893-2510-3 http://dx.doi.org/10.6027/TN2013-507 TemaNord 2013:507 © Nordic Council of Ministers 2013 Layout: NMR Cover photo: Erkki Oksanen, Metla Print: Rosendahls-Schultz Grafisk Copies: 130 Printed in Denmark This publication has been published with financial support by the Nordic Council of Ministers. However, the contents of this publication do not necessarily reflect the views, policies or recom- mendations of the Nordic Council of Ministers. www.norden.org/en/publications Nordic co-operation Nordic co-operation is one of the world’s most extensive forms of regional collaboration, involv- ing Denmark, Finland, Iceland, Norway, Sweden, and the Faroe Islands, Greenland, and Åland. Nordic co-operation has firm traditions in politics, the economy, and culture. It plays an im- portant role in European and international collaboration, and aims at creating a strong Nordic community in a strong Europe. Nordic co-operation seeks to safeguard Nordic and regional interests and principles in the global community. Common Nordic values help the region solidify its position as one of the world’s most innovative and competitive. Nordic Council of Ministers Ved Stranden 18 DK-1061 Copenhagen K Phone (+45) 3396 0200 www.norden.org Content Preface........................................................................................................................................................ 7 Summary ................................................................................................................................................... 9 1. Background and objectives ...................................................................................................... 15 1.1 Background and knowledge gaps ............................................................................. 15 1.2 Objectives .......................................................................................................................... 18 2. Approach and methods .............................................................................................................. 21 3. Nordic forests ................................................................................................................................ 27 3.1 Natural dynamics of Nordic forests ......................................................................... 27 3.2 Past and present human impacts on Nordic forests .......................................... 33 3.3 Ecological factors and variation in forest types................................................... 39 4. Main determinants of forest biodiversity ........................................................................... 45 4.1 Intact forest ecosystems and critical properties for biodiversity ................. 46 4.2 Forest types or habitats of particular conservation value ............................... 50 5. Forest carbon pools and fluxes ............................................................................................... 57 5.1 Definitions of ecosystem carbon accumulation ................................................... 57 5.2 Methods for studying forest carbon accumulation ............................................ 58 5.3 Driving factors of forest biomass growth .............................................................. 61 5.4 Driving factors of soil organic matter pools.......................................................... 64 5.5 The role of northern forests in the global carbon cycle .................................... 68 5.6 Effects of forest management on forest carbon sequestration ...................... 71 5.7 Old forests – carbon sources or carbon sinks?..................................................... 76 6. Old forest conservation: relevance for biodiversity and climate change mitigation........................................................................................................................................ 91 6.1 Forest carbon stocks and sequestration ................................................................ 91 6.2 Forest biodiversity and the carbon cycle ............................................................... 96 6.3 Albedo and other biophysical climate impacts of forest management .......... 98 6.4 Gaps in knowledge ....................................................................................................... 100 6.5 Implications for forest policy and management................................................ 102 References ........................................................................................................................................... 105 7. Sammendrag ................................................................................................................................ 119 8. Yhteenveto ................................................................................................................................... 125 9. Appendix ....................................................................................................................................... 129 9.1 Abbreviations and acronyms ................................................................................... 129 9.2 Tree species and their scientific names ................................................................ 129 Biodiversity, carbon storage and dynamics old northern forests 5 6 Biodiversity, carbon storage and dynamics old northern forests Preface Forests represent important ecosystems in the Nordic countries, for biodiversity, carbon sequestration, and amenity values like outdoor rec- reation. The significance of old forests for maintaining forest carbon stocks has recently come into stronger focus in the discussions of cli- mate mitigation policies. This has made it important to assess what is known about the amount and variation of carbon stocks in old and man- aged forests under various environmental conditions. In this report we give a scientifically based overview of the role of old forests in the car- bon cycle and how carbon uptake may represent co-benefits for the well-documented value of old forests for biodiversity. Our focus has been on the variation in forest carbon stocks and uptake of CO2. We have not considered the wider climate effects of forest management, e.g., re- lated to changes in albedo or the use of forest biomass for energy or various products. Such total system and life cycle studies would go far beyond the scope and resources available for this assessment. The responsibilities of the writing team have been divided as follows. Erik Framstad (NINA) has drafted the text for chapters 1–4 and 6, as well as being responsible for overall editing and project management. Heleen de Wit (NIVA) has drafted the text for chapter 5, except sections 5.3 and 5.6 which were drafted by Markku Larjavaara and Raisa Mäkipää (Metla), respectively. Lars Vesterdal (Skov og landskab, University of Copenhagen) and Erik Karltun (SLU) have contributed with input of studies, data, and text to various parts of the report. The work involved in producing this report has been supported by the Terrestrial Ecosystems Group under the Nordic Council of Ministers. We appreciate valuable input from colleagues in NINA to chapters 3 and 4 in particular, and contributions of photos from various colleagues (see credits per photo). We also wish to thank The Norwegian Mapping Au- thority, the Finnish Forest Research Institute (Metla), the Swedish Uni- versity of Agricultural Sciences (SLU), The Norwegian Forest and Land- scape Institute, and the Forest and Landscape Centre of the University of Copenhagen for permissions to reproduce figures 3.2 and 5.2. Oslo, October 2012 Erik Framstad Biodiversity, carbon storage and dynamics old northern forests 7 8 Biodiversity, carbon storage and dynamics old northern forests Summary Forests are key terrestrial ecosystems in the global climate system, rep- resenting major components of the carbon cycle. The Nordic countries have extensive forests with large