Distribution of oak tree-ring widths

What is the average ring width in big (above 1 m in diameter) southern Swedish oaks? The tree-ring increment in 69 big oaks analysed showed considerable variation (Fig. 2). The lower 5% and the higher 95% limits of the ring width distribution were 0.54 and 3.38 mm/year, respectively, and the 10% and 90% limits were 0.68 and 2.76 mm, respectively.

On average, ring width was about 1 mm.

Figure. Distribution of ring widths in oak trees larger than 1 m in diameter in Southern Sweden. Arrows point to (1) the average annual increment of large oaks (jätteekar) over the period 1953-2002 (Blomberg 2003), 0.49 mm/year; and (2) average ring width in 250-year old upland oak forests at the forest-steppe border in Europe (Neshataev et al. 1974a), 0.85 mm/year. Grey area indicates central 80% of ring width distribution.