Vegetation dynamics in Pinus nigra Arnold subsp. nigra 100 years after reforestation: two case studies in the central Apennines

We present here an integrated structural and floristic-vegetational study performed in two representative Pinus nigra subsp. nigra reforestation areas located within Natura 2000 protected areas in the central Apennines, as a mesotemperate thermotype. The aim was to determine the restoration state a century from the reforestation, in terms of a vegetation dynamics study. A diachronic analysis was also performed using data from the literature from a previous phytosociological study in 1973 in the same areas, and considering the adjacent native woods as the control. Although these two reforestation areas had similar ecology and vegetation, this comparison revealed modest structural and flora differences that are mainly related to geographical and topographical factors. This diachronic analysis highlights the structural and flora changes in the reforestation areas considered, and thus the structural and floristic-vegetation stages of the succession that was represented by the plant communities towards Ostrya carpinifolia forests (association, Scutellario-Ostryetum carpinifoliae) in 1973 and 2012. The minor coverage of conifers that was recorded for the two investigated sites corresponds to an increase in the nemoral species of the class Querco-Fagetea and to a widespread decline in ecotone and grassland species. Although the same trend is seen for the structural and floristic-vegetation dynamics, the differences that emerged from the comparison between these two reforestation areas are confirmed by the diachronic analysis. The status of the restoration is a function of the native woods, and thus is a function of the reference site. In this sense, we can consider that for the two sites the restoration status was similar, but not the same, because only within each site can the coenoses in 1973 and 2012 be considered as the developmental stages of the same dynamic process. However, if we consider the situation before reforestation, as derived from the historical documents, it can be seen that the natural vegetation dynamics was favoured, or at least accelerated, in the topographic positions that guaranteed greater edaphic humidity conditions. On the basis of the data obtained, we can say that 100 years after reforestation these two areas produced ecological conditions that guaranteed ingression of the nemoral species that were present in the surrounding woods, with their more than adequate regeneration. As well as representing an essential knowledge base for planning of future silvicultural actions, the knowledge acquired can provide useful indications of auto-ecological features of the species involved in dynamic restoration processes