Comparison of the understory vegetation of native forests and adjacent Robinia pseudoacacia plantations in the Carpathian-Pannonian region

•Black locust plantations are always lighter, warmer and less humid.•Contain more non-forest, ruderal and significantly higher number of alien species.•The largest impact of black locust was recorded on the mixed oak-hornbeam forests.•The smallest impact was recorded on the floodplain forest.