Restoration of xerothermic vegetation on 8 selected plots is one of the most important tasks included in the project. For this purpose we selected areas where the xerothermic grasslands had been observed, but was overgrown recently. Invasions of trees and bushes is one of the most important process responsible for the degeneration of such grassland patches. Moreover, some of the plots were afforested or transformed into arable fields.
However, the most degenerate grasslands are those which overgrown with Robinia pseudoacacia, which is extremely invasive and non native tree species in Poland. The species is dangerous for grasslands but also for other habitats during several reasons. First of all, its colonization rate is relatively fast and as a consequence expansion of the Robinia pseudoacacia is on average much faster as compared to other species, e.g. pines. Secondly, occurrence of the species affects positively concentration of nitrogen in the soil - the process leading to habitat eutrhropication. This in turn has negative effects on many non-forest habitats. Thirdly, allopatric influence of the Robinia on other species should be also taken into account. All the featrures cause that grasslands overgrown with Robinia pseudoacacia degenerates very fast and the process is difficult to reverse. As it was mentioned, the degeneration affects also habitat characteristics (soil) therefore in such cases, typical methods of grasslands protection (tree removing, pasturage) are ineffective. All this facts lead us to a decision that on such patches more advanced methods are necessary. Therefore, we planned the experiment: we are going to remove the upper layer of the soil on such patches. We expect that such operation will reduce considerably nitrogen concentration and seed density of Robinia. The soil removal will be preceded with tree cutting and removing of root systems of Robinia. We expect that the deeper layers of the soil will constitute much better habitat characteristics for xerothermic vegetation in comparison to current state. Finally, we are going to introduce xerothermic vegetation on the exposed layers of soil with two mathods: with seed translocation and micro-patches translocation (50cm x 50cm). All the activities related with soil removing were preceded with detailed soil characteristic research which will be repeated at the end of the experiment.