The aim of the study was to analyze the species composition of the dendroflora near four main roads in the city of Białystok, taking into regard their geographical and historical origin. The wildlife inventory was conducted in the vegetation season of 2011. The inventory revealed presence of a total of 837 trees and bushes representing 36 species and 18 families. The most abundant trees were those from the family Aceraceae (63.8%), while the most abundant bushes were those representing Rosaceae (48.9%). The contribution of native species (65.7%) was found to be about twice as high as that of alien ones (34.3%). The dominant species among the native trees was Acer platanoides L., while the principal bush species was Crataegus monogyna Jacq. The alien tree species were most commonly represented by Acer negundo L., and bushes - by Ligustrum vulgare L. Spontaneously settled trees and bushes were clearly dominant (59.9%) over those originating from plantations (40.1%). Among the native species of local origin, the prevailing species were synanthropic spontaneophytes (52%), including Acer platanoides and Tilia cordata Mill. Anthropophytes were more abundantly represented by diaphytes (22.7%), followed by kenophytes (10.4%). The most abundant species among diaphytes was Ligustrum vulgare, and among kenophytes - Acer negundo.
The study was carried out to determine the floristic diversity in the Sajna River valley, in the region of direct and indirect impact of the hydroelectric power station planned to be built in the village of Sarkajmy. Phytosociological diversity of plant communities and floristic diversity were analysed taking into account the predicted influence of the planned power station on the Sajna River. The study was performed in 2010 using field methods and GIS localisation of analysed sites. 73 phytosociological surveys were made and particular floristic patches were identified. Global Positioning System (GPS) surveys were used to delimit the different plant communities and spot the sites of protected plant species. Thirteen plant communities were identified in the study area, five of which are of European importance that require protection within Natura 2000 sites. This group of plant communities comprises four forest plant communities (Salicetum albo-fragilis, Ficario-Ulmetum, Tilio-Carpinetum, Acer platanoides-Tilia cordata) and one herbaceous community (Urtico-Calystegietum). One species under strict protection (Daphne mezereum L.) and five species under partial protection (Viburnum opulus L., Ribes nigrum L., Asarum europaeum L., Eurhynchium angustirete (Broth.) T.J.Kop., Eurhynchium striatum (Schreb. ex Hedw.) Schimp.) were noted. The presence of valuable natural habitats and protected species in the Sajna River valley indicates the natural potential of the area and illustrates its biological diversity. The studied area is threatened by negative impact of the hydroelectric power station planned to be built on the Sajna River, since water damming will flood the river terrace that will lead to the formation of a 7.25 ha pond of.