Mark Dobrowolski

Seed for restoring natural ecosystems is an expensive and finite resource. Yet seedling emergence is notoriously low in mining rehabilitation and restoration projects more generally. Unlocking this potential in broadcast seed has been critical to restoring a diverse kwongan ecosystem at Iluka’s Eneabba mineral sands mine, in the mid-west of Western Australia.

Using an innovative combination of rehabilitation practices in the sandy soils of Eneabba—seed burial, land imprinting, and an artificial soil crust—two-fold more seedlings emerged from broadcast seed in 2017 than from standard rehabilitation practice of ripping and seed broadcast. To combine and automate these practices in a single pass, we designed, built, and commissioned tractor-drawn equipment named ‘Flora Restorer’. Flora Restorer spreads fertiliser, scarifies the uneven soil, air-seeds a diverse size and shape seed mix, land imprints and thereby buries the seed, and sprays the soil surface with dilute bitumen emulsion forming an artificial soil crust to stop wind and water erosion.

Over the last four years of use, consistently two- to three-fold more seedlings have emerged from broadcast seed using Flora Restorer than from previous rehabilitation practice. Independently, long-term botanical monitoring has also demonstrated revegetation improvement using Flora Restorer, with species richness more than 50% higher and native plant cover more than double compared to rehabilitation at Eneabba over the previous 20 years. Flora Restorer demonstrates that large improvements in revegetation outcomes are possible in mining rehabilitation by automating seed sowing in combination with land imprinting and application of an artificial soil crust.

Crown rust fungus, Puccinia coronata f.sp. lolii is an obligate biotrophic pathogen of ryegrasses which causes significant reductions of herbage yield, palatability and digestibility. Genetic diversity in virulence has been reported in all the major temperate regions of the world and is therefore a major problem for pasture and turf breeders developing varieties with durable resistance for crown rust. Knowledge of the genetic variation present both within and between Australasian crown rust populations is essential for the efficient production of resistant varieties. A total of 11 efficient simple sequence repeat (SSR) markers developed from a urediniospore-derived expressed sequence tag (EST) resource have been used for Australasian intraspecific genetic diversity analysis. Seventy-two single pustule samples comprising three main populations from both North and South Islands of New Zealand and from south-eastern Australia were genotyped. The analysis identified 59 distinct genotypes, high levels of genetic diversity being detected both within and between populations. All methods of analysis detected no significant difference between isolates from the North and South Islands of New Zealand (p > 0.05), and high intrapopulation diversity between Victorian isolates. However high population differentiation (p < 0.001) was detected between Victorian isolates and those from the South Island (PhiPT [estimate of genetic variability = 0.101) and especially the North Islands (PhiPT = 0.162) of New Zealand. Genetic dissection of crown rust population structure within Australasia will inform the magnitude of gene pyramiding required for the development of varieties with durable resistance.