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The floristic composition of Spiraea hypericifolia shrubberies distributed in Georgia is studied for first time. 256 species of vascular plants, which belong to 172 genera and 49 families, were recorded. Leading families by content number of species are: Poaceae - 28 species (10.9%), Asteraceae – 27 (10.5%), Fabaceae – 20 (7.8%), Rosaceae – 18 (7%), Brassicaceae – 16 (6.3%), Lamiaceae – 16 (6.3%), Apiaceae – 11 (4.3%), Caryophyllaceae – 11 (4.3%), Asparagaceae – 7 (2.7%). Spectrum of life forms is as follows: phanerophytes – 37 species (14.4%), chamaephytes – 8 (3.1%), hemicryptophytes – 109 (42.6%), geophytes – 33 (12.9%), therophytes – 69 (27%). Based on the analysis of the systematic structure of the flora, the composition and ratio of chorotypes and the composition of life forms, 4 main directions of florogenetic connections were identified: Mediterranea, South-West Asia, Europe and Eurasian steppe. It can be concluded that the formation of the Spiraea hypericifolia shrubberies in Georgia took place under the influence both of the Ancient Mediterranean and Boreal floristic centers. Nevertheless, the Ancient Mediterranean connections are more expressed. The dominance of local (Caucasian) species in the spectrum of chorotypes (14%) emphasizes the originality of the studied shrubberies. [ABSTRACT FROM AUTHOR]

How variation in factors controlling species abundance and distribution between native and non-native ranges compares to that within ranges remains poorly understood. We used a globally distributed ruderal, Centaurea solstitialis ( Centaurea), to explore the possibility that the importance of those factors exhibits great variation between and within ranges. To test our hypothesis, we established seed addition experiments with soil disturbance (turnover and control) and biocide (fungicides, insecticide, and control) treatments in two regions within native (the Caucasus and south-western Turkey) and non-native (the western United States - US - and central Argentina) distributions. Also, we estimated the rate of vegetation recovery after disturbance (resilience) and related it to Centaurea density in experimental plots. Disturbance strongly increased Centaurea density in all regions. Density was similar between the native Caucasus and non-native Argentina and much greater in those regions than in the native Turkey and non-native US in biocide-free plots. Fungicides had positive effects on density in the US and negative ones in the Caucasus and Argentina, resulting in no differences between those three regions and greater density in the US than Turkey. Insecticide applications promoted Centaurea density in Turkey and Argentina, but inter-regional comparisons of density in treated plots were comparable to those in biocide-free plots. Overall, plants were smaller and less fecund in Turkey than the other regions, except the US. The greatest fungal attack was documented in Turkey, and herbivory was stronger there and in Argentina than in the Caucasus and US. The resilience of the local community explained a large proportion of variation in Centaurea density. These results support our hypothesis, and reveal that the speed at which competition is re-gained after disturbance may influence global variation in Centaurea abundance. Because many ruderals exhibit native and non-native distributions, our results are likely to be generalized to other systems. [ABSTRACT FROM AUTHOR]