Can a fundamental change in forest management improve the forest carbon balance of mixed oak forests in Central Europe?

The potential of altering forest management strategies to support the European Union’s (EU) climate-mitigation goals has been widely debated. However, evidence is particularly scarce for direct comparisons between alternative management strategies under comparable site conditions, making it challenging to design robust forest management recommendations. In this study, we investigated mixed oak forests in a dry region of Bavaria, Germany, (i) to evaluate how fundamentally different management strategies effect the in situ carbon balance and (ii) to identify possible drivers of carbon storage and sequestration. We assessed total ecosystem carbon storage and aboveground carbon sequestration in 93 plots (31 stands), comparing High Forests (HF), Coppice-with-Standards (CWS) and an unmanaged Nature Reserve (NR). Using a model averaging approach for multiple linear regressions, we assessed the drivers of carbon storage and sequestration. Total carbon storage differed only marginally and was not statistically significant (p > 0.05) among the three management strategies with, on average, 173.8 t C ha⁻¹ in HF, 191.4 t C ha⁻¹ in CWS, and 192.1 t C ha⁻¹ in NR. Aboveground carbon sequestration was, on average, highest in CWS (3.51 t C ha⁻¹ yr⁻¹) compared to HF (2.40 t C ha⁻¹ yr⁻¹) and NR (2.16 t C ha⁻¹ yr⁻¹), yet these differences were also not statistically significant. Indicators of structural diversity, including maximum tree height, and variation in diameter at breast height, were significantly positively associated with carbon storage. We did not identify any statistically significant variables explaining carbon sequestration. Our results indicate that a fundamental shift in management from HF to CWS or ceasing management entirely (NR) is unlikely to yield large mid-term carbon benefits in mixed oak forests. We conclude that even a fundamental change in the management of mixed oak forests is unlikely to substantially contribute to achieving national and EU climate targets. • Similar carbon storage in oak forests despite diverging management strategies. • Coppice-with-standards might exhibit the highest carbon sequestration rates. • Structural diversity is positively correlated with carbon storage. • Limited potential to enhance the carbon balance by changing the management approach.