Abstract
Soft water lakes, or so-called lobelia lakes, which are inhabited by a specific vegetation composed of isoetids, have been subjected to intense research aimed at evaluating their condition and conservation status for many years in Poland. At the time of Poland’s accession to the European Union and the implementation of the EU Habitats Directive, these lakes were classified as natural habitat 3110. In accordance with the provision of the Habitat Directive a comprehensive methodology for monitoring and classification of the state of this habitat has been developed. Using this methodology, two monitoring trials (in 2009–2010 and again in 2016–2017) were carried out at 45 and 43 sites of the 3110 natural habitat, respectively. These studies confirm the high sensitivity of these poorly buffered aquatic ecosystems to all external influences, both natural and anthropogenic. The overall conservation status of the 3110 habitat in Poland showed a relatively high stability, with similar proportions of sites classified as favourable (FV), unfavourable inadequate (U1) and unfavourable bad (U2) between 2009–2010 (35%, 49% and 16%, respectively) and 2016–2017 (33%, 56% and 11%, respectively). Out of 43 sites examined in 2016–2017, 29 remained unchanged compared with the results of the previous survey concerning their overall status. Results of the monitoring research also allow for the observation and evaluation of mechanisms and directions of changes in the functioning of these ecosystems. Based on the experiences from two series of monitoring conducted so far, the methodology has been assessed as appropriate for the assessment of the conservation status of the 3110 natural habitat, however, some modifications and additions have been suggested.