To ensure maintenance of biologically valuable grasslands, several grassland restoration and management activities has been performed in Sigulda and Ludza municipality within the project. The monitoring activities has been performed to assess the impacts of two grassland management measures – restoration of overgrown habitats and application of biogas production end-product – digestate – on yields and biodiversity of EU priority grasslands habitats. Full report (in Latvian) is available “Zālāju biotopu atjaunošanas darbu un izmantoto zālāju apsaimniekošanas metožu izvērtējums”.
Habitat restoration activities has been done in 31 grasslands with the total area of 122 ha in total. The monitoring results shows that most of the habitat restoration activities has been successful. The average area of the restored grassland patches has increased from 3 to 4 ha, its overgrows with trees and shrubs has decreased from 27% to 4% and there is no longer a dense layer of litter that interfered with seed germination and decreased the occurrence of less competitive species. As green hay method for improvement of the species saturation was applied only in July 2017, it was not possible to make a detail assessment of its effectiveness within the project. Thanks to vegetation description that were prepared along the monitoring transects in these sites, it will be possible to evaluate the impact of the method after the project ends.
Monitoring results of the digestate application shows that even relatively small doses of digestate (9– 30 kg N/ha) increases productivity and reduces the diversity of plant species, but it has little effect on the diversity of the beetle fauna. In all plots where digestate were applied the productivity increased by 2–13% while in all control plots it dropped by 11–30%. The saturation of plant species (number of species per square meter) in control plots increased by 7 species an average, while in the digestate application sites it increased or even decreased by 1–2 species. Besides, the increase of the species saturation in some digestate application plots is more likely attributed to the changes in grassland management practices not to the digestate application. All grasslands that were used for the valuation of grassland management methods were not managed or mulched or managed with late mowing before the project started, while during the project they were mown and harvested in July.
At the same time there were no statistically significant differences in the diversity of beetle fauna between the digestate application and control plots. In some management sites the highest diversity was observed in the plots with digestate application while in other ones – in the control plots. It is believed that the effect of the digestate application on beetle fauna would be more pronounced over the longer term, but during the project it was not possible to assess that.