Temporal changes of vascular plant diversity in response to tree dieback in a mediterranean lowland forest

Abstract

Palo Laziale wood is a small biotope of about 129 ha situated along the north coast of Rome. It is one of the last remaining patches of an ancient lowland floodplain forest that once covered the coastal area of the Lazio region. It contains several habitats and species of high conservation interest which has been included in the Natura2000 network. The forest suffered an impressive dieback event in 2003, coinciding with a particularly hot and dry summer.

In the framework of an ecological restoration project (LIFE PRIMED LIFE17 NAT/GR/000511), a preliminary assessment of the biotic and abiotic components of the ecosystem was carried out, including a floristic analysis. This analysis was compared with that conducted in 1990 to assess whether there was any change in the species composition also following the forest dieback. Comparisons between biological forms, chorotypes and the Ellenberg indicators were also made in the analysis.

The total flora of the site increased from 462 to 490 species. Moreover, there has been a turnover of species with the disappearance of some grassland and halophytic species and the appearance of allochthonous/ruderal and freshwater habitat species. Despite this, the flora remained unchanged in ecological terms, demonstrating a certain resilience of the plant species, confirming this approach to identify declining processes and support ecosystem-based restoration actions elsewhere.