Structure and increment in pure and mixed stands of beech and silver fir in the Calabrian Apennine

Abstract

The paper describes the variations of the transit periods, the percentage and current volume increment in pure and mixed forests of silver fir and beech in three different areas of the Calabrian Apennines: the forest of Serra San Bruno, the forest of Ferdinandea and Monte Scorda. The information about the dendro-auxometric characteristics of the stands in all the three areas were estimated through surveys carried out in a total of 109 plots. For the study more than 509 carrots were taken incrementally. The percentage increment of the standing trees was determined by the method of Schneider, while for the percentage increment of the forest the method of Borggreve was used. The transit periods are always decreasing with increasing diameter. In general, the mixed forests transit periods are lower than the pure structures ones, and among these, the pure silver fir forest lower than the pure beech forest. In Ferdinandea and Monte Scorda the transit periods are almost always less than the forest of Serra San Bruno. The lowest percentage increments were recorded in pure beech forests, while in mixed forests, especially in Serra San Bruno, the percentage increments are higher than in pure forests. The highest current increments took place in pure silver fir forest and mixed forests, especially in Serra San Bruno, while the lowest current increments were recorded in the beech forests. According to the results achieved, the mixed forest ensures a greater volume growth rate than that of pure forests; this confirms that the mixed forest is also a highly productive system, stable and capable of maintaining the natural factors of production.