| Summary: | No information currently exists on the floristic structure and richness of the <i>Artemisia alba</i> scrubs in Romania and their regional/local environmental drivers. We aimed to fill these knowledge gaps by also considering physiognomically similar communities from Hungary, Serbia and Bulgaria. A total of 89 phytosociological relevés, including 43 performed in Romania, were analysed through clustering, constrained ordination and generalised linear mixed models. The Carpathian and Pontic scrubs were clustered into three distinct groups, which were assigned to as many new syntaxa. Differences in the regional species pool and elevation have the strongest effects on floristic dissimilarities between all studied communities. As opposed to the bare soil fraction, the elevation and slope have positive but no singular effects on species richness in the Pontic-Carpathian coenoses. Species diversity declines steadily with increasing shrub cover in all these communities. The relative cover of annuals has contrasting effects on species richness, positive in the most xerophilous communities and negative in their most mesophilous counterparts. The relative number of annuals is only (negatively) related to overall species richness in the coenoses least affected by moisture deficit. Overall, species diversity is driven mainly by soil water availability and, to a lesser extent, by the relative abundance of shrubs and annuals.
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