Temporal changes in diversity of vascular flora accompanying Salix viminalis L. plantations

In recent years, there has been increasing interest in the floristic diversity of agroecosystems, particularly for plant conservation. While old plantations claim to be more floristically diverse, little is known about this for Salix viminalis L. plantations. The aim of study was to analyse the vegetation accompanying S. viminalis and its dynamics as plantations age. The vegetation was identified in 20 plantations, based on 244 phytosociological relevés. For each species, the following were defined: botanical family, geographical and historical groups, origin of apophytes, biological stability, life-form, botanical class and phytosociological class. The relative coverage of major plant groups was statistically processed using the analysis of variance with a linear mixed model. The flora of S. viminalis plantations is rich and diverse; in central Poland, it consisted of 193 plant species. These species belonged to many phytosociological classes, of which two dominated: Molinio-Arrhenatheretea (46 species) and Artemisietea vulgaris (32 species). Perennial species, meadow, woodland, and shrub apophytes, as well as hemicryptophytes, were prevalent. As the plantations aged, the proportion of perennial species, meadow, woodland, and shrub apophytes increased, while therophytes and anthropophytes declined. Photophilous species dominated mainly in young crops (4-5 years old), but their coverage and frequency decreased over time. With plantations age, vascular flora diversity (total number of species) and coverage of ecologically important groups (Poaceae family, Molinio-Arrhenatheretea class) decreased. These were gradually replaced by mega- and nanophanerophytes and species from the A. vulgaris class. The stabilisation of flora occurred after eight years of willow cultivation.