Is south-side partial harvesting the key to improving oak seedling height growth when accounting for vegetation cover and browsing pressure?

A challenge in continuous cover forestry is converting even-aged stands to uneven-aged stands, which can be achieved by releasing advance regeneration through partial harvesting. Partial harvesting increases light and reduces competition, but its effects on oak seedling growth depend on harvesting intensity, direction, understory vegetation, and browsing pressure. Here, we conducted a three-year experiment (2016–2019) in central France, applying partial harvesting with varying intensities (7–30% of the initial basal area) within an 18 m radius around 217 naturally regenerated sessile oak ( Quercus petraea (Matt.) Liebl.) seedlings in fenced and unfenced plots. We monitored seedling height growth, understory vegetation, and browsing impacts. Results showed that south-side harvesting uniquely influenced seedling growth, with positive effects only above a threshold of understory vegetation cover and for taller seedlings. Browsing exclusion further enhanced growth. Understory vegetation cover remained unaffected by partial harvesting, possibly due to drought conditions. These findings suggest that targeted south-side harvesting, combined with assessing seedling height and understory competition, can improve oak regeneration. Still forest managers should consider climatic conditions and may need complementary understory interventions to optimize outcomes.