Pedunculate oak decline in southern Belgium: a long-term process highlighting the complex interplay among drought, winter frost, biotic attacks, and masting

Since 2013, pedunculate oak (Quercus robur L.) mortality has been observed in the Ardennes region of Belgium. We aimed to understand the current decline by retrospectively (1945–2015) studying radial growth patterns of trees classified by three health statuses (reference, declining, and dying) and by linking them to abiotic and biotic hazard history, which we recorded and quantified. Our results show that oak mortality in the Ardennes is a long-term process, with 1987 as a tipping point for growth trajectories of declining and dying trees. That year was preceded by two growth crises (1976–1981... Mehr ...