Not enough trees - Scaling up koala habitat restoration using seed enhancement technologies

Large-scale ecological restoration is a crucial tool for improving the quality and extent of habitat for wildlife. In Australia, 25,000 hectares of land is to be restored to support habitat connectivity for the Endangered koala (Phascolarctos cinereus). However, limited funding is a barrier to achieving restoration of this scale without the integration of new technologies and approaches. Seed enhancement technologies (SETs) are commonly used in agriculture to improve plant establishment and growth while reducing seed wastage; yet SETs are rarely used in restoration. Here, we tested the efficacy of SETs with five native tree species favored by koalas. Using a greenhouse trial, we measured emergence, time to emergence, growth rates, and survival up to 7 weeks post planting. At 33 weeks post-planting, we measured total biomass, root: shoot ratios, and the specific root length. SETs resulted in comparable emergence and survival and promoted a longer time to emergence relative to bare seeds. Importantly, seedlings grown from SETs yielded higher average growth rates (0.3 mm/week higher), total biomass (5.93 mg higher) and root: shoot ratios (0.258 higher) relative to seedlings grown without SETs. These findings underscore the applicability of SETs to native species to support large-scale koala habitat restoration by increasing the growth rate and size of seedlings at the early life stage.