Soil seed banks of secondary vegetation on the Port Hills and Banks Peninsula, Canterbury, New Zealand, and their role in succession

Abstract

Abstract Soil seed banks at 21 sites covered with poor quality pasture, bracken femland, scrubland of broom or gorse, and various forest types, were examined by germinating seed in soil samples. At most sites the composition of upper and lower soil layers was similar. Persistent, deeply buried seed banks of Cytisus scoparius, Ulex europaeus, and more rarely Sophora microphylla, were discovered at seven sites, four of which lacked that particular species in the above-ground vegetation, and are thus considered to be of a former vegetation type. Forest sites tended to have more seeds and more species represented in the soil seed bank. Although an average of only 35% of the species in the seed bank were represented above ground at the sampling point, this rose to 60% within 5 m, and 72% within 10 m of that point. Those species further away were mostly widespread pasture weeds, even within forest sites, and are interpreted as being recently dispersed and transient. Large quantities of Juncus spp. in some sites...