Experimental translocation of the Peep Hill hop- bush into conservation reserves in the semi-arid Mallee of South Australia

Summary

The Peep Hill hop-bush (Dodonaea subglandulifera), Vulnerable under IUCN criteria and confined to small, unprotected roadside and private-land populations in South Australia's semi-arid mallee, was translocated by the South Australian Seed Conservation Centre into two protected reserves, electric-fenced Yookamurra Sanctuary and the free-ranging Brookfield Conservation Park, both several kilometres from the nearest wild population, to compare transplants against direct seeding and assess herbivore impact. In June 1992, 30 five-month-old seedlings were planted at three sites in each park, alongside direct-seeding trials using heat-pretreated and untreated seed, with wire baskets excluding herbivores from some emerging seedlings. Direct-seeded plants germinated poorly (up to 14%) and suffered heavy early mortality from moisture stress and, at unfenced Brookfield, grazing; all surviving direct-seeded plants were ultimately killed by a severe 2006-2009 drought. Transplanted seedlings fared better, reaching 70% survival at Yookamurra and 50-60% at Brookfield after ten years and first fruiting in their fourth year, though the same drought later killed nearly 70% of Yookamurra's larger, more water-demanding plants while Brookfield's smaller plants lost only 15%; twenty years on, 13% of Yookamurra transplants and 45% of Brookfield transplants survive, with no new recruitment observed. Difficulties included the lack of suitable protected habitat within the species' natural range, lower rainfall at both sites than in wild populations, and herbivore grazing and burrowing at Brookfield. The project rates itself successful, crediting effective predator-exclusion fencing at Yookamurra and clear evidence that transplants outperform direct seeding, despite substantial drought losses and no natural recruitment after two decades.