The importance of soil seed banks for biodiversity restoration in degraded grasslands

To effectively restore species and habitat diversity in poorly managed degraded grasslands, it is important to understand the relationship between the soil seed bank and aboveground vegetation. Our study aimed to describe changes in soil seed bank composition compared to aboveground vegetation under two ploughing regimes (annual and single ploughing) of narrow strips on the edges of artificially grassed old fields in Podyjí National Park, the Czech Republic. We used the seed germination method, multivariate analyses and Kruskal–Wallis tests to compare differences in the proportion of species and individual numbers in the soil seed bank based on the origin of species (native species, archaeophytes, neophytes) and their habitat preferences (segetal, ruderal, grassland, endangered species) in two types of grasslands with varying soil moisture content. The highest numbers of individuals were present in annually ploughed dry grasslands whereas single ploughing in mesic grasslands resulted in greater species diversity. Ploughing increased the numbers of seedlings of all groups and promoted archaeophytes, grassland specialists, native species and ruderals in dry grasslands whereas mesic grasslands hosted segetal specialists and neophytes. Threatened plants and invasive species rarely emerged from the soil seed bank. The study also revealed the highest similarity between the soil seed bank and aboveground vegetation in annually ploughed plots. It gradually decreased during vegetation succession in the single ploughed variants. Whereas annual ploughing supported segetal specialists, single ploughing promoted grassland species in dry habitats. Neither type of ploughing can be recommended in mesic grasslands because of the risk of inducing the spread of expansive ruderals or invasive neophytes.