Polder Gardna IX – January 2024 (fot. L. Schiefelbein)

As we informed in previous news, in January 2021 we modernized the drainage system in the Gardna IX and Gardna X polders. As a reminder, the modernization included:
• reconstruction, reconstruction and renovation of culverts (42 pcs.),
• reconstruction, reconstruction and renovation of culverts (49 pieces),
• desilting the bottom of ditches and canals (8,762 meters),
• mowing the bottom of ditches and canals (15,501 meters),
• renovation of the lakeside flood embankment, right lake. Gardno – restoration of the original condition and increase of the embankment crown (450 m),
• demolition of the lakeside dike (400 meters).

The main goal of implementing the above activities was to improve the operation of the drainage system. The faulty drainage system made it impossible to adapt water conditions to the needs of nature conservation and the occurrence of many species of fauna and flora, modernization of the system enabled water management in line with nature protection needs. Moreover, as part of the task, mowing was carried out in the area of polder IX, specifically in section 142, which directly affects the occurrence of birds and plant species in this section. Throughout the entire period of implementation of the activities, and also currently, environmental monitoring is carried out to document the ecological effect of the activities carried out. SPN employees monitor the impact of the investment in hydrological, botanical and ornithological terms.
As part of hydrological monitoring, 20 piezometers, i.e. devices for testing water levels, were installed in the area of work carried out in 2015. Thanks to this, we have comprehensive knowledge about changes in water levels in the polders.

As a result of the activities carried out, we are able to extend the period of water occurrence on the surface by up to 30 days a year, and the time of artificially lowering the water level by pumping has been shortened, because water is more effectively drained and admitted to the surface of the polders.
In connection with the botanical monitoring carried out, we also observed changes caused by the modernization of the system and the simultaneous mowing of area 142. Restoring the use of semi-natural communities, such as rushes and meadows, through regular mowing, is an important element of the strategy for the protection and revitalization of the natural environment. We can already say that the direct effect is a decrease in the share of reed in the studied patches of sedge rushes. In order to maintain the achieved effects, it is necessary to continue mowing treatments in subsequent years.

 In times of global, declining trends in the number of wetland birds and ongoing climate change, the above results constitute a measurable and valuable effect of the project, which, however, requires further monitoring. To sum up, all aspects of nature monitoring indicate that the modernization and mowing activities carried out have a positive impact on the protection of this valuable area. It remains to continue research in the field of hydrology, botany and ornithology and maintain or improve the ecological effect achieved so far.