Developing a species selection index for seed-based ecological restoration in Peninsula Shale Renosterveld, Cape Town

• Seed viability was generally high, indicative of good germination potential.
• Emergence was moderate–high for half the species, suggesting in-field success.
• For 22 of the 31 species, seedling emergence was significantly less than viability.
• Discrepancies in viability and emergence point to sub-optimal germination cues.
• Most species exhibited moderate-high restoration species potential.

The considerable risk factors associated with ecological restoration make the reintroduction of appropriate species critical to restoration success. In seed-based restoration efforts, using high quality seed is central to good in-field yields; consequently, determining the physiological status of seed prior to large-scale collection and use is important. To gain insight into the suitability of species for use in large-scale seed-based restoration efforts, this study set out to determine the seed viability and seedling emergence of 31 little-studied renosterveld species through laboratory and glasshouse trials, respectively. The outcomes of these seed quality tests were assessed in conjunction with several additional criteria, suggested throughout the literature as relevant to species selection and seed collection, towards determining an overall score, a restoration species index, as a measure of how suitable each species is likely to be in future seed-based restoration efforts. Among the 31 selected species, seedling emergence and to a lesser extent seed viability were variable yet moderate to high for the majority of species. The restoration species index presented here, drawing several considerations into a single, novel approach to species selection, proved useful in this study where the vast majority of species exhibited moderate to high potential.