## 4 Results
Three species (_Andromeda polifolia_, _Oxyococcus palustris_ and _Vaccinium uliginosum_) occurred only in sector PFR, two species (_Betula pubescens_ and _Salix caprea_) were absent only in sector FR in both study seasons, and one species (_Vaccinium myrtillus_) was absent only in sector R in the same period (compare Figure 4). Figure 4: A dendrogram and a heatmap of the hierarchical cluster analysis of 35 species and four sectors in 2015 and 2018 based on [PERSON]’s coefficient and the average linkage method (the presence of a given species in the phytocoenoses is marked with yellow colour, and its absence with red colour). The classification of shore species of Lake Piaseczno that were identified in 2015 and 2018 in terms of historical-geographic range showed that spontaneouspytes (Sp) constituted the majority in the studied phytocoenoses (45.9%, 108 species). Apophytes (Ap) reached a 38.7% contribution (91 species). The remaining groups, classified as antropophytes (A) (archeophytes (Arch, 10 species), kenophytes (Ken, 6 species) and diaphytes (0 species)), were represented in a very scarce degree or not at all. It is worth mentioning that 20 of the identified species showed unidentified historical-geographic affinity. The above classification permitted the calculation of indicators of antropogenic transformations in the flora of the entire shore of Lake Piaseczno in 2015 and 2018, which were analysed both together and separately (changes concerned only 2018): total synanthropisation (WS-c) equalled 86.29% (2018, 85.71%); total apophytisation (WAp-c) equalled 73.38% (2018, 72.26%); and total anthropophytisation (WAn-c) reached 12.9% (2018, 13.44%). The values of indicators of anthropogenic transformations in the flora of the shore of Lake Piaseczno, when divided into sectors, were similar (Figure 5). The lowest values of WS-c in both study seasons were recorded for sector PFR (2015, 84.61%; 2018, 78.46%; total, 84.84%), and the highest for sector FR (2015, 98.21%; 2018, 106%; total, 98.21%). The values of WAn-c showed the opposite pattern. The lowest values of the indicator were determined for both study years in the case of sector FR (2015, 8.92%; 2018, 8.0%; total, 8.92%), and the highest in sector PFR (2015, 14.03%; 2018, 13.84%; total, 13.63%). For WAp-c, the extreme values were variable: in 2015 for sector R (80.0%); in 2018 for sector PFR (64.61%); and, in the case of the joint analysis of both years (total), for sector PFR (71.21%) (Figure 5). The classification of the identified plant species to selected index numbers of higher plants, describing their habitat preferences, shows that the primary component of the shores of the analysed lake was comprised of plants that are characteristic of fresh and moist soils. In terms of trophic status, they prefer habitats that are moderately abundant in nutrients and eutrophic components and occur on moderately acidic and neutral soils, loamy-sandy or sandy, with higher than average permeability. In terms of content of organic matter, habitats of the shore flora of Piaseczno Lake had mineral-humus and organogenic soils that were related to the peatbog areas (compare Table 6). Based on the selected parameters in the analysed sectors of the lake shore, a high contribution (in majority exceeding 50%) was reached by stenobionts with a relatively narrow range of ecological tolerance (Table 6). Figure 5: The values of indicators of antropogenic transformations in the flora of shore sectors of Lake Piaseczno in 2015 and 2018. WAn-c, total anthropophytisation; WS-c, total synanthropisation; WAp-c, total apophytisation. A total of 37 plant species was identified in the plant communities of the littoral (macrophytes) in all sectors of Lake Piaseczno in 2007 and 2018 (23 species in 2007 and 35 species in 2018). They belonged to 24 families from 5 botanical classes. The highest representation concerned class LILIOPSIDA (24 species, 12 families), and the lowest representation concerned classes EQSISTOPSIDA, POLIPODIOPSIDA and BRYOPSIDA (one species and one family each).