Preparing Threatened Plants for Translocation: Does Home Soil Addition and Nutrient Loading Improve Growth and Flowering?

Translocation of threatened plants is increasingly being used as a conservation or mitigation action. The success of this practice is mixed and methods to increase likelihood of success are commonly investigated. Using a long-lived perennial shrub endemic to the Sydney Basin, Australia, as a case study, we examined the role of pre-planting nutrient loading (High, Low) and addition of Provenance (home soil) on growth and flowering, where Provenance soils had on average 50% lower nutrients than the Low treatment. We found that Provenance- and Low-treated plants grew better under propagation compared to High treatments, but these differences did not persist. At 11 months post-planting, Provenance-treated plants had growth rates no different from any other treatments and that plants under both High and Provenance soil treatments had higher peak flowering events, indicating that Provenance-treated soils could confer a flowering advantage akin to fertilisation. This study demonstrates that there were no negative effects of growing plants using home soil, despite a lower nutrient status than standard propagation medium. Translocations, particularly reintroduction or augmentation, should consider home soil treatment within pilot studies as a simple and cost-effective method of potentially reducing transplant shock, providing ethical and phytosanitary measures are addressed.