Accounting of Forest Carbon Sinks

Today, forests in the northern hemisphere are a sink for carbon dioxide (CO2) from the

atmosphere, partly due to changes in forest management practice and intensity. Parties of

the Kyoto Protocol had the option to elect to account for direct human-induced carbon (C)

sources and sinks from land management activities since 1990. The effect of age–class

structure of a forest landscape resulting from past practices and disturbances before the

reference year 1990 should be excluded, but methods for ‘‘factoring out'' the effects of this

age–class legacy on carbon emissions and removals are lacking. The legacy effect can be

strong and can even overwhelm effects of post-1990 management. It therefore needs to be

‘‘factored out'', i.e., removed from the direct human-induced post-1990 effects. In this study

we examine how the contributions to forest biomass carbon stock changes of (1) past (pre-

1990) disturbances and harvest and (2) recent (post-1990) changes in forest management can

be differentiated in present and future observable carbon dynamics in managed forest

ecosystems. We also calculate the consequences of different accounting rules for the

magnitude and direction of accountable C stock changes in European countries in the

period 2013–2017.

Different accounting approaches are compared in terms of applicability and their ability

to provide incentives for management changes to increase carbon sinks and reduce carbon

sources. We demonstrate implications of the various ways of