Conclusions
(1) The change in the state of the restored plant community with time was an irreversible process characterized by spontaneous increase in its total biomass quantity C T and total number of plant species N associated with increase in its enthalpyH , Gibbs free energy G and entropy S . Species enrichment was the cause for the decease in mass ratiox i and biomass growth potentialμ i. The changes in the thermodynamic factorsf /C T ands /C T due to decrease inx i with increasing N followed the basic laws of thermodynamics. The criterion △N > 0 can be generally applied as an index for determining the direction of spontaneous changes in an open thermodynamic system with continuous input of matter and energy.
(2) The conducted analysis did not fully prove the use of the Shannon-Wiener index as a biodiversity index for the investigated plant communities. The biodiversity of a plant community cannot be determined by the number of individuals if there are significant differences in individuals among species of the plant community. In contrast, the entropy factor s was proven to be a suitable diversity index. As a state function related to system composition, s can be applied as a diversity index for all types of systems.