Independent Review of Direct Seeding Techniques to Restore Grassy Woodland: Five Case Studies on the Cumberland Plain

ABSTRACT This study investigates the effectiveness of several direct seeding techniques in the restoration of Cumberland Plain Woodland, with a focus on understanding the influence of environmental variables and seeding techniques on outcomes. A series of direct seeding trials were conducted across nine sites previously dominated by exotic grasses on the Cumberland Plain (Dharug Country), Western Sydney NSW between 2013 and 2018. The present study tracked the diversity and cover of native and exotic forbs and grasses using the NSW Biodiversity Assessment Method (BAM) up to 10 years subsequent to direct seeding at the largest five groundcover restoration sites. The diversity and cover of native and exotic forbs and grasses differed markedly between the five sites. No site reached the Cumberland Plain Woodland plant community type BAM benchmark for native grass and forb cover and species richness. Sites on a residual soil landscape exhibited significantly higher native richness and native forb richness compared to sites on an alluvial soil landscape. Sites with evidence of native macropod grazing exhibited significantly lower exotic cover and richness. The site that was scalped to a greater depth and received double the sowing seed density, Parrot Farm, exhibited the highest total native groundcover, native grass and native forb species richness and the highest native forb cover. These findings suggest that the direct seeding techniques implemented at Parrot Farm, and the environmental context in which it exists, are more conducive to establishing a diverse range of native species. This case study does not allow for robust statistical analysis, but provides valuable insights for enhancing the biodiversity and resilience of Cumberland Plain Woodland through improved direct seeding strategies.