Revaluing unmanaged forests for climate change mitigation

We deduce that the use of CO2 flux measurements alone does not allow conclusions on a superiority of unmanaged to managed forests for mitigation goals. This is based on the critical consideration of uncertainties and the application of system boundaries. Furthermore, the consideration of wood products for material and energetic substitution obviously overrules the mitigation potential of unmanaged forests. Moreover, impacts of nitrogen immissions, CO2 enrichment of the atmosphere, increasing temperatures and changed precipitation patterns obviously lead to a meaningful increase in growth, even in forests of higher age.An impact of unmanaged forests on climate change mitigation cannot be valued by CO2 flux measurements alone. Further research is needed on cause and effect relationships between management practices and carbon stocks in different compartments of forest ecosystems in order to account for human-induced changes. Unexpected growth rates in old-growth forests – managed or not – can obviously be related to external impacts and additionally to management impacts. This should lead to the reconsideration of forest management strategies.Following the FAO definition, “unmanaged forests” are characterized by the lack in formal management, e.g. in the preference of natural development of forests for nature conservation purposes [1]. Forest Europe, UNECE and FAO reported 1.476 million hectares of the forest area in central Europe as “undisturbed by man” in 2012 [2]. In core areas of German national parks and German forest nature reserves at minimum 0.1 million hectares of unmanaged and mainly old-growth forests can be found in which logging and thinning are not allowed [3]. Although these strictly protected areas represent less than one percent of the total forest area in Germany, they meaningfully contribute to carbon storage in forests. However, unmanaged forests are not part of the reporting on carbon stocks in forests under the Kyoto Protocol (but to regular UNF