Syntaxonomical and Ecological Diversity of Class Artemisietea vulgaris Lohmeyer et al. in Tx. ex von Rochow 1951 in Bulgaria

Class Artemisietea vulgaris includes thermophilic and (sub)xerophytic ruderal vegetation, which consists mostly of biannual and perennial seminitrophilous to nitrophilous species, widely distributed in the temperate and the submediterranean zones of Europe. The study presents a comprehensive review of its ecology and syntaxоnomy on the territory of Bulgaria, based on 160 relevés stored in the Balkan Vegetation Database and selected using the “EuroVegChecklist Expert System”. Numerical classification and ordination were performed by hierarchical agglomerative clustering and Detrended Correspondence Analysis. The diagnostic species were determined by calculating the Phi-coefficient. The syntaxonomical diversity of the class Artemisietea vulgaris on the territory of Bulgaria is presented by 2 orders (Agropyretalia intermedio-repentis, Onopordetalia acanthii), 3 alliances (Convolvulo arvensis-Elytrigion repentis, Dauco-Melilotion and Onopordion acanthii), 10 associations (Convolvulo arvensis-Elytrigietum repentis, Falcario vulgaris-Elytrigietum repentis, Convolvulo arvensis-Brometum inermis, Cardarietum drabae, Tanaceto vulgaris-Artemisietum vulgaris, Melilotetum albo-officinalis, Berteroetum incanae, Poo compressae-Tussilaginetum farfarae, Potentillo argenteae-Artemisietum absinthii and Carduo acanthoidis-Onopordetum acanthii) and 1 plant community (Achillea pannonica-Elytrigia repens). One order, two alliances and nine associations were discovered for the first time in the country. All of the syntaxa are well separated floristically and ecologically in the ordination space. The associations of the alliance Dauco-Melilotion represent initial stages of succession of antropogenic habitats and has higher species diversity, whereas those of the alliances Convolvulo arvensis-Elytrigion repentis and Onopordion acanthii represent more stable antropogenic vegetation types and have lower species richness.