Relationships between vegetation and seed bank in sand pits: Effects of different restoration approaches and successional age
Abstrakt
Questions Our study examined the relationships between the seed bank and above-ground vegetation in spontaneously revegetated and forestry-reclaimed sand pits. We asked the following questions: (a) What is the composition of the seed bank and above-ground vegetation? (b) How do they develop over the course of succession within the two different restoration approaches? (c) What is the representation of target and undesirable species in the seed bank and above-ground vegetation? and (d) Could the seed bank serve as the source for target vegetation restoration? Location Trebon Basin, Czech Republic.
Methods Three successional stages and two types of restoration approaches were considered. Bray-Curtis similarity was used for describing the similarity between above-ground vegetation and the seed bank.
Representation of target (dry sandy grassland), desirable (woodland, wetland, mesic grassland) and undesirable (synanthropic) species was assessed. Results The type of restoration approach exhibited stronger effects on the above-ground vegetation than on the seed bank.
The similarity between the seed bank and above-ground vegetation decreased during succession. Undesirable species formed the dominant species group in the seed bank regardless of successional stage and the type of restoration approach.
Target species were represented especially in the above-ground vegetation of young successional stages. Only half of the number of target species appeared in the seed bank in comparison to above-ground vegetation and their number further rapidly decreased in older stages of succession.
Conclusions The result showed that the seed bank of sand pits could be considered as a potential resource mainly for synanthropic species, but it cannot serve as the only source for the eventual restoration of the target vegetation of an open sandy dry grassland after potential clearing, once it becomes overgrown by forest. Consequently, maintaining young successional stages is desirable if we wish to support species typical of dry sandy grassland.