Diversity and spatial distribution of Opuntia spp. in the Mediterranean Basin

This work offers a methodology based on statistical tools and GIS applications in a study of the adaptability
of Opuntia to the environment, applied on the Mediterranean island of Sardinia. Detailed surveys
of habitats containing naturalized populations of Opuntia spp. were made in order to select study sites.
The topographic, soil and climatic features of these are described. The local biotypes are ascribed mainly
to the spineless Opuntia ficus–indica (L.) Mill. and to the spiny Opuntia amyclaea Ten. Although introduced
at different times, for different uses, they have adapted to the Sardinian environment and established in
the wild. The distributions of the two species differed. The FloraMap modelling approach was used to
simulate Opuntia distribution as a function of the island’s climate and produced individual distribution
maps using the accession points for the two species. Our analysis showed that environmental conditions
at elevations above 800 m are the main limiting factors for the presence and abundance of Opuntia in
Sardinia. Spatial representation developed by GIS software indicated temperatures below 2 C as the
threshold impairing the species naturalized distribution. The statistic results also show that variation in
rainfall does not affect Opuntia spatial distribution in Sardinia.