Disturbance management and restoration of temperate grasslands

Temperate grasslands in southern Australia are critically endangered, and remaining remnants are often degraded requiring restoration. While decades of research have identified the importance of disturbance, specifically fire, for maintaining diversity, questions remain around how to restore long unburnt, degraded grasslands. A typical restoration approach has been to reintroduce fire based on the idea that restoring a more historical disturbance regime may promote native plant diversity. Reintroducing fire has potential to improve biodiversity if native species remain in the seedbank or can disperse in from neighbouring remnants. In this talk, I will explore several lines of evidence that suggest degraded grasslands are relatively stable and likely require more than changed disturbance management to recover lost species. Firstly, a review of literature exploring changed disturbance management found few instances of improved plant diversity when management changed from introduced stock grazing to fire. Secondly, the re-introduction of cultural fire into long unburnt grasslands did not increase native plant diversity compared to adjacent unburnt plots. Finally, the combination of fire and seed addition was needed for successful seedling establishment; biomass removal without fire did not promote seedling emergence. Altogether, these results suggest degraded grasslands are seed-limited but the addition of seed without fire-promoted germination is unlikely to promote recruitment.