Climate change and wetland ecosystems : the effects on halophilous vegetation diversity in il-Ballut ta’ Marsaxlokk Natura 2000 site (Malta)

Abstract

Climate change poses a fundamental threat to the wetlands. The Mediterranean basin is a biodiversity hotspot, and wetlands are important for maintaining this status. The current study evaluated the halophilous vegetation diversity of one of the most relevant Maltese wetlands, Il-Ballut ta’ Marsaxlokk Natura 2000 site, also identified under the Water Framework Directive. A vegetation analysis was carried out according to the Braun–Blanquet approach. The processed dataset included both data from the literature and unpublished data. To quantify vegetation structure and diversity, a hierarchical classification (Chord distance; Ward linkage) and diversity and ecological indices were performed. Diachronic analysis of the taxonomic diversity indices and the Ellenberg indicator values were taken into account. We used an NMDS analysis to assess the ecological fingerprint of the vegetation. In addition, we provided an actual vegetation map for Il-Ballut ta’ Marsaxlokk, based on drone orthophotos. We identified five EU Directive habitats in the study area (1150*, 1310, 1410, 1420, and 92D0) of which one (1150*) was reported for the first time. The ecological fingerprint of the halophilous vegetation has undergone changes over time, particularly due to increasing temperatures. In fact, the results showed that nutrients and temperature were the strongest environmental drivers of the site. The results and methodology of this study demonstrate how vegetation studies can serve as tools to improve knowledge, management actions, and landscape planning of Natura 2000 sites.