PhD Candidate: Paola Pisetta Raupp

PhD Supervisors: Dr Yolima Carillo (WSU), Associate Professor Paul Rymer (WSU), Associate Professor Uffe Nielsen (WSU), Dr Ian Oliver (DCCEEW)

Project Summary: Ecological restoration is vital for recovering degraded ecosystems and restoring biodiversity, especially in critically endangered Cumberland Plain Woodlands (CPWs). Native understorey species, which contribute to approximately 90% of plant diversity in CPW and support essential ecosystem processes, are often overlooked in restoration efforts..

Current restoration practices largely focus on re-establishing tree canopies, leaving significant challenges in restoring the native understorey. In particular, competition from invasive species such as African lovegrass poses a substantial barrier to success. Techniques like topsoil removal, combined with planting monocultures or diverse native species, are commonly used to suppress exotics, but their efficacy remains uncertain. This study explores 1) How do topsoil removal, plant diversity, and water availability affect the establishment of native understorey species and the propensity for exotic invasions? and 2) what soil chemical, physical and biological properties are associated with successful establishment and reduced invasion? A mesocosm experiment was conducted in a rainout shelter using soils from a partially degraded CPW site. Pots were planted with three diversity treatments: a monoculture of Themeda triandra (Kangaroo grass), a medium-diversity mix of four native species, and a high-diversity mix of 12 native species. These treatments were combined with three watering regimes based on climate predictions for 2070. Following plant establishment, African lovegrass seeds were introduced to assess resilience to exotic invasions. Plant germination, survival, and growth will be assessed at the end of the experiment. Soil samples are being collected for physicochemical and biological analysis. Results from this study will provide insights into the effectiveness of topsoil removal and plant diversity in promoting native understorey recovery and reducing exotic species invasion under varying water availability, offering guidance for future restoration efforts.

Collaborators: Local Land Services (NSW Government)