Reestablishing a Keystone Species in an Arid Coastal Environment: Saltbush (Salsola nollothensis) in Namibia

Abstract

Beach hummocks are important ecological components of coastal ecosystems. Although hummocks are naturally adapted to harsh conditions, reestablishing them in arid areas poses great challenges. During a collaborative project, researchers from Namdeb Diamond Corporation and the Millennium Seed Bank Partnership investigated practical methods to reestablish saltbush (Salsola nollothensis) beach hummocks to restore areas disturbed by alluvial diamond mining. With focus on simple methods that can be implemented over large areas, collecting seed-containing debris, placing windbreaks, and seeding these with debris are some of the means currently investigated. Preliminary findings indicate that seed quality may deteriorate quickly if seeds are stored in ambient conditions, and storage under controlled conditions and/or seed harvesting shortly before restoration is recommended. Laboratory tests indicate a naturally high proportion of empty seeds, possibly short seed longevity, and that seeds must not be buried too deeply for seedling emergence. Further, seasonal and site-related variation in seed production influences the quality and amount of viable seeds available. All this suggests a complex set of environmental conditions that have to be met to achieve natural recovery or restoration goals. This project illustrates the benefits of partnerships in restoration that made it possible to investigate practical field questions with scientific sophistication, making an international initiative relevant to applied restoration ecology in a developing country.