Diversity of vascular flora accompanying Salix viminalis L. crops depending on soil conditions.
The main purpose of the study was to assess the impact of energy willow (Salix viminalis L.) crops on the vascular flora diversity of agroecosystems in Łódź voivodeship in central Poland. The studies were carried out in the years 2013 and 2014 on seven commercial plantations which were established in various soil conditions, on five soil agricultural complexes. In total, 50 phytosociological relevés were made using the Braun-Blanquet method. The evaluation was conducted on the basis of an inventory of vascular flora accompanying energy willow crops, involving determination of phytosociological classes and multifaceted analysis. For each species the following parameters were determined: family, geographical and historical group, apophyte origin, biological-stability, life-form, and status as an invasive, endangered, near-endangered, or protected species. The number of vascular plant species accompanying energy willow crops was high (133 species in total) and depended on the soil conditions (soil agricultural complex - SAC). The largest number of species (74) was found on silty and sandy soils, too wet or too dry (SAC 9), while the lowest (45) was on very dry sandy soils (SAC 7). These species belonged mainly to three phytosociological classes: Molinio-Arrhenatheretea, Stellarietea mediae, and Artemisietea vulgaris. In all habitats, most species (83%) were rare and more frequent (I and II constancy class). The species were mainly apophytes - native species (76.7%), and among them meadow plants, woodland and shrub species were predominant. An important part of flora was endangered species (Agrostemma githago L.). Ten invasive plant species which mostly occurred very rarely were also found. Salix viminalis L. crops favor the maintenance of agroecosystem biodiversity, as confirmed by the values calculated for the Shannon-Wiener, Simpson and inverse Simpson indexes. The floristic diversity on the Salix viminalis L. plantations proved to be slightly higher than on typical arable crop plantations.