Stand, tree and crown variables affecting cone crop and seed yield of Aleppo pine forests in different bioclimatic regions in Tunisia

摘要

In Tunisia, the Aleppo pine seed has a great importance, since in the last decades human consumption has risenconsiderable. Thus its regeneration and seed production capacities are important factors to take into account to reachthe necessities of the country. To study the production of cones and seeds of Aleppo pine, Tunisia’s native Aleppo pineforests were surveyed in summer 2006, using 79 plots (40 × 25 m: 1,000 m²) spread over four bioclimatic zones. Standand tree characteristics, crown dimensions and cone/seed variables were measured from an average tree of each plot(i.e. a total of 79 trees). Recorded data were submitted to simple and multiple regression analyses for explaining thevariability in crown volume and crown surface, cone number and seed yield per average tree. Results showed a negativecorrelation between the stand density, crown characteristics and number of cones and seeds harvested from theaverage tree. For crown volume and surface, age, stand density, tree height, diameter at breast height, crown diameterand crown height were important explanatory variables under multiple regression analyses. For cone number per tree,only the age, stand density and total height were the most determinant variables. Matures cone number per tree andcone mass per tree were the most informative parameters for the total seed yields per tree. Finally, forest managersshould know that crown size affects cone and seed crop of the Aleppo pine individual tree grown in Tunisia, but hasno effects on seed number per cone and seed mass per cone.