2 MATERIALS AND METHODS
Study area and trees
The study area was a permanent 27-ha research plot (564 m × 480 m) located on the northern slope of the Babia Góra massif (49°35'00.6"N 19°31'10.2"E) in the Western Carpathian
Mountains (Fig. \ref{336753}). The altitude ranged 1170–1310
m a.s.l. At the timberline (around 1400 m a.s.l.) the mean annual temperature was approximately 2°C, and the annual precipitation was just above 1400 mm \cite{Szwagrzyk_2015,b2004}. The dominant vegetation is an old-growth Norway spruce forest (Plagiothecio-Piceetum), with a large variation of local openings, due to climate-change amplified disturbances \cite{_ywiec_2012,Holeksa_2017}. The site is strictly protected within a national park.
The study rowan trees (mean stem diameter: 14.4 ±4.7 cm) were 131 fruiting individuals, a subsample of all rowans present in the research plot (228-310 individuals, depending on census year), monitored since the year 2000 \cite{Kondrat_2024}. The distribution of rowans was clumped, which is related with the spruce stand gap dynamics, and the tendency of rowans to thrive near gap edges \cite{_ywiec_2012b} (Holeksa and Żywiec 2005).