Engineering the regeneration niche for the restoration of temperate grassy woodlands

Abstract

Digging animals, considered ecosystem engineers in temperate grassy woodlands worldwide, play an important role in the creation of germination niches for ground-layer plant species. However, there is limited understanding of the influence that digging animals may have on temperate grassy woodlands, or on the role they may have for the restoration of these systems. This prompted a study into the dynamics of the native plant regeneration niche, and the small disturbances created by the foraging of digging animals such as the eastern bettong (Bettongia gaimardi). My thesis included investigation of (1) the germination response in bettong-created pits and (2) artificial replication as a possible restoration technique. I selected four sites of Themeda grassland within Mulligans Flat Woodland Sanctuary. The study compared the germination of hand-seeded native forbs (small flowering herbaceous plants) in natural bettong pits, an artificially replicated pit, an artificial ‘scrape’ (removal of vegetation and soil surface disturbance to create a gap in the grass canopy), and a control. This design had the intention of addressing the following questions. 1) Do natural pits promote the germination and establishment of seedlings? 2) Can artificial pits create a similar environment for germination and establishment? 3) Is the possible facilitation effect of germination due to the removal of vegetation, or the structural effects of the pit? This study found that all three disturbance treatments significantly increased germination of the native forbs yam daisy (Microseris walteri) and blue devil (Eryngium ovinum) compared to the control. There was also no significant difference in germination between artificial disturbances mimicking bettong foraging pits, and the scrape to create a gap in the grass canopy. Therefore, the results suggested there is potential to artificially replicate small scale disturbance events, like animal digging, to help restore diversity in temperate grassy woodland ecosystems. It also supported the hypothesis that the creation of gaps in the grass canopy is a major factor driving the plant response to bettong digging in grassy woodlands. A future recommendation is to further investigate the effects of bettong-created pits on the longer-term growth and establishment of native forbs. Additionally, I suggest increasing the scope and scale of my study to include an additional site to MFWS. These avenues of study would further increase the available information on the influence of eastern bettong digging on the growth of native forbs, and in doing so allow more informed recommendations to management.