The sabulicolous therophytic associations in Sicily: new insights through the statistical approach, stressing the continuum versus discrete model of plant communities

This study presents an updated syntaxonomic review of the annual psammophilous plant communities from coastal dunes and inland territories of Sicily. A total of 301 releves were collected. The releves data were analysed using classification (WPGMA, similarity ratio) and ordination methods (detrended correspondence analysis and principal component analysis). Eighteen plant communities were recognized, four of which are described here for the first time (Rostrario littoreae-Tuberarietum villosissimae, Filigini asterisciflorae-Loeflingietum hispanicae, Astragalo kamarinensis-Coronilletum repandae, Sileno coloratae-Ononidetum variegatae cutandietosum maritimae). The surveyed associations are ascribed to the following orders: Cutandietalia maritimae (annual associations of semi-fixed dunes) and Malcolmietalia (inland sandy soil communities). Moreover, for this latter order, a new alliance, Filagini asterisciflorae-Linarion humilis, that groups the therophytic communities from fossil dunes and deep sandy soils of the inland of the Sicily, is proposed. Another aim of this study is to check and compare the discrete model of plant community against the continuum model along environmental gradients.