Legacies of past land use challenge grassland recovery – An example from dry grasslands on ancient burial mounds

Due to large-scale agricultural intensification, grasslands are often restricted to habitat islands in human-transformed landscapes. There are approximately half a million ancient burial mounds built by nomadic steppic tribes in the Eurasian steppe and forest steppe zones, which act as habitat islands for dry grassland vegetation. Land use intensification, such as arable farming and afforestation by non-native woody species are amongst the major threats for Eurasian dry grasslands, including grasslands on mounds. After the launch of the Good Agricultural and Environmental Condition framework of the European Union, in Hungary there is a tendency for ceasing crop production and cutting non-native woody plantations, in order to conserve these unique landmarks and restore the historical grassland vegetation on the mounds. In this study, restoration prospects of dry grassland habitats were studied on kurgans formerly covered by croplands and Robinia pseudoacacia plantations. Soil and vegetation characteristics were studied in thespontaneously recovering grasslands. The following questions were addressed: 1; How does site history affect the spontaneous grassland recovery? 2; Do residual soil nutrients play a role in grassland recovery? In former croplands, excess phosphorus, while in former Robinia plantations, excess nitrogen was present in the soil even four years after the land use change and grassland vegetation was in an early or mid-successional stage both on the mounds. The results showed that, without proper management measures, recovery of grassland vegetation is slow on mounds formerly used as cropland or black locust plantation. However, restoration efforts, focused on the restoration of mounds formerly covered by croplands, can be more effective compared to the restoration of mounds formerly covered by forest plantations.