Temporal increase in the extent of pine stands in Sardinia (Italy).

Temporal changes in the distribution range of plant communities and habitats should be considered for optimal conservation. However, this information is often lacking. In this research, we investigated the changes in the spatial distribution pattern of the plant communities characterised by the presence of three Mediterranean pines considered native or putative native to Sardinia (Italy), namely Pinus halepensis, P. pinaster, and P. pinea. We analysed historical and current aerial photographs to prepare maps of the past and current distribution of natural pine formations, complemented with the aid of pine-related toponymy maps and interviews with local people. We calculated how the surface of natural pine formations varied across time, and found a high rate of recovery during the last decades. This rate is doubled when compared to the average extent of other Sardinian woody formations in the same period. Among the three pine species, the area of P. halepensis and P. pinaster formations increased the most. We also found that about 90% of pine formations fall within protected areas. More than 128 ha of natural pine formations are included in the priority habitat 2270, while those included in habitat 9540 cover 1100 ha. Our study provides a complete survey of the distribution of natural Sardinian pine formations, along with the quantification of their increase in the last decades, thus highlighting the importance of diachronic analyses for monitoring spatial changes in plant communities. We suggest considering the trends in the extent of vegetation formations and habitats for conservation purposes.