Influence of aromatic dwarf-shrub canopies on plant community diversity and composition in Sardinian coastal harsh habitats

Alfredo MACCIONI ¹, Erika BAZZATO ², Silvia MACIS ², Michela MARIGNANI ², Emmanuele FARRIS ³

1 Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Piandanna, 4, 07100 Sassari (SS), Sardinia, Italy - 2 e.INS- Ecosystem of Innovation for Next Generation Sardinia ¹, 2 e.INS- Ecosystem of Innovation for Next Generation Sardinia - 3 Department of Life and Environmental Sciences, University of Cagliari, Viale S. Ignazio, 13, 09123 Cagliari (CA), Sardinia, Italy ², 1 Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Piandanna, 4, 07100 Sassari (SS), Sardinia, Italy - 2 e.INS- Ecosystem of Innovation for Next Generation Sardinia - 4 National Biodiversity Future Center NBFC, Palermo 90133, Italy ³

Numerous ecological processes define plant species richness and community composition: plant establishment and survival are particularly sensitive to micro-habitat structure and environmental conditions, especially in Mediterranean harsh environments. To assess whether plant community richness and composition in a mosaic of coastal Mediterranean herb and garrigue habitats was determined by the canopy of aromatic dwarf-shrubs, between April and July 2023 we conducted a study on three model species (Helichrysum italicum subsp. tyrrhenicum, Teucrium capitatum subsp. capitatum, and Salvia rosmarinus) and examined each species at three different sites in North-Western Sardinia (Italy). At each species × site combination, we randomly sampled 10 individuals. We recorded the presence or absence of vascular plants both under the shrub canopies and in adjacent open areas, using point transects. Statistical analyses revealed significant differences in community composition between areas under and those outside the canopies of all the three model species. While the presence of canopies did not influence species richness, it did affect beta dispersion for all three shrub species and the mean community composition of H. italicum subsp. tyrrhenicum and T. capitatum subsp. capitatum. Preliminary data suggest that the presence of these canopies led to significant differences in species composition between areas beneath the dwarf-shrubs and adjacent open areas, indicating that conditions under the canopies may influence plant diversity in comparison to the surrounding open habitat. Moreover, our results highlight significant differences in species richness, mean composition, and beta dispersion beneath the canopies of the model species, suggesting that the dominant species play a key role in shaping plant diversity. We hypothesize that these preliminary outcomes, which provide insight into the dynamics of biocoenosis and plant-plant interactions in Mediterranean harsh environments, may be more strongly influenced by plant specialized metabolites at both in soil litter and aerial parts and roots of aromatic dwarf-shrubs, rather than by the simple shading effects of the canopies themselves.

Main author career stage: Postdoc / Fellow

Contribution type: Talk

First choice session: 2. Ecology

Second choice session: 3. Biodiversity and global change