The restoration of Strandveld and Succulent Karoo degraded by mining: an enumeration of topsoil seed banks

Abstract

This study was initiated to assess the potential of top- soil replacement to meet the objectives of the mining rehabilitation plan at Brand-se-Baai along the West Coast of South Africa. Seed bank size was determined seasonally for six vegetation units by means of the seedling emergence method. A mean seedling density of 2 725m − 2 was recorded, dominated by annual species. Temporal variation in the seed bank was significantly higher than spatial variation at a vegetation unit level. Mean seedling densities ranged from 1 612–3 276m − 2 between vegetation units, and from 838–7 772m − 2 between seasons. The seasonally-germinable seed bank was significantly larger in autumn than in the other seasons. When compared to the potentially-germinable seed bank, the size of the summer, winter and spring seasonally-germinable seed banks greatly underestimated the true seed bank size. Topsoil replacement will go far to restore plant densities recorded in the pre-min- ing vegetation and will be essential for the successful re-vegetation of mined areas. It is critical to take seasonal changes in seed bank size into account when planning re-vegetation strategies.