abstract

Population dynamic of shrubby and pre-forestal formations in the umbro-marchiginno Apennines (central Italy). The aim of this research was to study some aspects of the dynamics of those populations that are the most active and dominant in the grassland-wood transition stages in the Central Apennines. The study concerned Spartium junceum and Fraxinus ornus populations and was carried out in permanent plots. These populations characterise the grassland-wood transition through the shrub and pre-wood stages.
It was established that S. junceum populations reach their maximum expansion in 20 years. Afterwards, the competition among individuals becomes very intense provoking a decrease in the actual number of individuals that, as a result, tend to develop a uniform spatial distribution. This stage, which can be defined as the stage of steadiness, can last for long since the population remains steady. This situation starts to change when the S. junceum population is reached by pre-forest species such as F. ornus. This species is able to settle even under the thick cover formed by S. junceum during the stage of steadiness. Probably, this cover gives rise to microclimatic conditions suitable for F. ornus. In fact, the excessive cover occurring in the stages preceding the stage of steadiness does not allow the settlement of F. ornus. On the contrary, this species is able to settle in those plots where the intense intraspecific competition provoked a decrease in the population density of S. junceum. Afterwards, F. ornus tends to develop faster than S. junceum gaining the dominant position.

keywords

Central Apennines, Fraxinus ornus, Italy, permanent plots, population dynamics, Spartium junceum