Influence of stand and tree attributes and silviculture on cone and seed productions in forests of Pinus pinea L. in northern Tunisia

The present work studied if cone and seed productions were related to tree and stand parameters (age, crown size, stand density and tree social status) in stone pine (Pinus pinea L.) stands in Mekna forest (III), Northern Tunisia. The cones were collected in summer 2011 on 10% of the trees sampled in the different trunk diameter classes. They were counted, weighted and classified according to their age (two or three-year-old) and healthy or damaged. Three cones (three-year-old) with different sizes (small, medium and large) per sampled tree were harvested and brought to the laboratory. Seeds were extracted from the cones and their number and total weight per cone were determined. Filled or empty seeds were recorded. The findings showed that cone and seed productions are conditioned by tree size, especially crown volume, age and social status. The number of filled or empty seeds depends on the cone weight. Data showed that cone and consequently seed productions in Mekna III forest were low to extremely low for the considered year. Problems could arise from this deficiency in the future, not only for nut market but also for stand regeneration and species conservation on a long term scale.