Pinus pinea L. plant trait variations in response to tree age and silvicultural management and carbon storage capability

Pinus pinea plant trait variations in response to tree age and silvicultural practices were analyzed. Samplings were carried out in stands with trees of different ages inside the Presidential Estate of Castelporziano (Italy). The results highlight the largest structural changes occurring between 15- and 45-year-old trees when the ratio between tree height (H) and crown height (CH) largely increased (from 1.45 to 3.48). The CH decrease (tree stands older than 45 years) was due to the transformation of the crown from a spherical shape in young trees to an umbrella-shaped in adult trees when most of the basal branches were lost. Leaf area index (LAI) changed with stand density and in response to the stone pine developmental stage showing the largest value in 34-year-old tree stands. The biomass was the largest in 104-year-old tree stands (241.1 ± 9.8 t ha−1) and carbon stored (Cst) varied from 0.01 ± 0.005 to 1.63 ± 0.07 t (15- and 104-year-old trees, respectively). Morphology varied significantly between 1- and 2-year-old needles, with the specific needle weight (SNW) having the highest values in 2-year-old needles. LAI was correlated (p < 0.05) to H/CH ratio and crown volume (Vc) which changed in response to stone pine growth and silvicultural treatments. The long-term monitoring of P. pinea stands could be easily achieved by LAI measurements.