Limited sink but large storage: biomass dynamics in naturally developing beech (Fagus sylvatica) and oak (Quercus robur, Quercus petraea) forests of northwestern Germany

1. Currently, the dynamics underlying the storage and acquisition of biomass, and thus carbon, in naturally developing forests are under debate. A better understanding of the biomass dynamics of forests is needed to clarify the role played by naturally developing forests in the mitigation of climate change.

2. Long-term monitoring data from unmanaged strict forest reserves (SFRs) in northwestern Germany were used to analyze the biomass dynamics of pure beech, mixed beech, and mixed oak forests. A complete balance of aboveground woody biomass (biomass) and growth, density-dependent and -independent mortality, as well as deadwood decay was derived. Density-independent mortality served as a proxy for disturbance severity.

3. After a time of abandonment (TSA) of 50 years, the average biomass ranged between 334 t ha-1 in mixed oak and 478 t ha-1 in pure beech stands. The net change in biomass was positive in all forest types. Density-independent mortality and decay rates were much lowe...