## 4 Results
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Life Forms**} & \multicolumn{3}{c}{**2015**} & \multicolumn{3}{c}{**2018**} \\ \cline{2-7}  & \multicolumn{2}{c}{**Number of Species**} & \multicolumn{2}{c}{**Proportion (\%)**} & \multicolumn{2}{c}{**Number of Species**} & \multicolumn{2}{c}{**Proportion (\%)**} \\ \hline
**M** & 17 & 7.29 & 17 & 7.55 \\
**N** & 18 & 7.72 & 18 & 8 \\
**Ch** & 7 & 3 & 7 & 3.11 \\
**C** & 3 & 1.28 & 4 & 1.77 \\
**H** & 139 & 59.65 & 133 & 59.11 \\
**G** & 34 & 14.59 & 33 & 14.66 \\
**T** & 34 & 14.59 & 32 & 14.22 \\
**Hy** & 26 & 11.15 & 25 & 11.11 \\
**li** & 2 & 0.85 & 2 & 0.88 \\
**PP** & 1 & 0.42 & 1 & 0.44 \\
**ua** & 1 & 0.42 & 1 & 0.44 \\
**TOTAL** & **282** & **120.96** & **273** & **121.29** \\
**Species occurred** & 233 & 100 & 225 & 100 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Proportions of different plant life forms in the flora of the studied sectors of Lake Piaseczno in 2015 and 2018. **M**, megaphanerophytes (trees generally growing to a height of more than 5 m); **N**, nanophanerophytes (shrubs and small trees from 0.5 to 5 m in height); **Ch**, woody chamaephytes (buds >25 cm above ground); **C**, herbaceous chamaephytes (buds <25 cm above ground); **H**, hemicryptophytes (buds at ground level); **G**, geophytes (buds in soil); **T**, therophytes (annuals); **Hy**, hydrophytes and helophytes (buds in water); **li**, lianas (plants rooted in soil that require support); **PP**, semi-parasites; and **ua**, species of undetermined affinity. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**CLASS**} & \multirow{2}{*}{**EQUISETOPSIDA**} & \multicolumn{3}{c}{**2015**} & \multicolumn{3}{c}{**2018**} \\ \cline{3-10}  & & \multicolumn{3}{c}{**Sectors**} & \multicolumn{3}{c}{**Sectors**} \\ \hline
**Families** & _Species_ & **PFR** & **R** & **RA** & **FR** & **PFR** & **R** & **RA** & **FR** \\ \hline Denstaediaceae & _Equisetum fluviatile_ & & & & + & + & & & + \\  & _Equisetum palustre_ & + & & & & + & & & \\ \hline \multirow{2}{*}{**CLASS**} & \multirow{2}{*}{**POLIPODIOPSIDA**} & \multicolumn{3}{c}{**2015**} & \multicolumn{3}{c}{**2018**} \\ \cline{3-10}  & & \multicolumn{3}{c}{**Sectors**} & \multicolumn{3}{c}{**Sectors**} \\ \hline
**Families** & _Species_ & **PFR** & **R** & **RA** & **FR** & **PFR** & **R** & **RA** & **FR** \\ \hline Denstaediaceae & _Pteridium aquilinum_ & & + & + & & & + & + \\ \hline Dryopteridaceae & _Dryopteris filix-mas_ & + & + & + & & + & + & & \\ \hline Thelyteridaceae & _Thelyteris palustris_ & + & & & & + & & \\ \hline \multirow{2}{*}{**CLASS**} & \multirow{2}{*}{**CONFIGROPSIDA**} & \multicolumn{3}{c}{**2015**} & \multicolumn{3}{c}{**2018**} \\ \cline{3-10}  & & \multicolumn{3}{c}{**Sectors**} & \multicolumn{3}{c}{**Sectors**} \\ \hline
**Families** & _Species_ & **PFR** & **R** & **RA** & **FR** & **PFR** & **R** & **RA** & **FR** \\ \hline Pinaaceae & _Pinus sylvestris_ & + & + & + & + & + & + & + \\ \hline \multirow{2}{*}{**RAZEM**} & \multirow{2}{*}{**56**} & \multicolumn{3}{c}{**132**} & \multicolumn{3}{c}{**115**} & \multicolumn{3}{c}{**138**} \\ \cline{3-10}  & & \multicolumn{3}{c}{**233**} & \multicolumn{3}{c}{**225**} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._0.81 (FR-FR) and 0.91 (PFR-PFR), suggesting insignificant changes in the species composition of plants (Table 5, Figure 3b). In the case of tree and shrub vegetation, somewhat more complete information was provided by a hierarchical classification analysis with the Jaccard's coefficient as the similarity measure, which was performed both for plant species and for shore sectors of Lake Piaseczno (Figure 3a,b). At the first stage, it permitted the designation of three more or less-diverse groups of plant species, characterised by a higher measure of co-occurrence in the phytosociological context, belonging to five groups: Oxycocco-Sphagnetea, Scheuzcherio-Caricetea fuscae, Bethetum pubescentis, Salicetum pentandro-cinereae and Querco-Piceetum.