The herbivore-predator-fire nexus: a literature review and case-study from the mesic forests of south-west Victoria
AuthorGeary, William Lachlan
AffiliationOffice for Environmental Programs
MetadataShow full item record
Document TypeMasters Coursework thesis
Access StatusOnly available to University of Melbourne staff and students, login required
© 2017 William Lachlan Geary
Trophic interactions and disturbance events can shape the structure and function of ecosystems. However, top-down (e.g. predation, herbivory) and bottom-up (e.g. fire, climate, resources) processes and their potential ecological effects are rarely considered concurrently. This is despite their capacity to interact and impact other species. We reviewed the literature on the interactions between herbivores, fire and predators, and their impacts on critical weight range mammal persistence in south- eastern Australia’s mesic forests. Based on our review, we developed a conceptual model of the herbivore-predator-fire nexus and the potential outcomes for critical weight range mammals in forest ecosystems. Our conceptual model predicts that management actions such as lethal predator control and prescribed fire may cause increases in herbivore populations, which can then flow on to influence vegetation and the persistence of other species. We then tested how native herbivore distributions are influenced by predator control, fire, vegetation type, and other environmental variables. Occurrence data for red foxes and four native herbivores (red-necked wallaby, black wallaby, grey kangaroo and brushtail possum) were collected from 240 sites across a landscape-scale predator-management experiment in south-western Victoria (‘Glenelg Ark’) and modelled against these variables. The effects of fire and predator control on herbivore occurrence was very limited, with climate, proximity to farmland and topography more influential in shaping herbivore occurrence. Our results suggest that, in the Glenelg Ark system, the distributions of herbivores are determined by bottom-up factors, rather than top-down factors. These results may be due to the resource subsidies provided by the region’s high productivity and high proportion of agricultural landuse dampening trophic interactions in the system. Understanding the drivers of herbivore distribution is an important step in predicting the effects of herbivory on other species, particularly after management interventions such as predator control and fire.
Keywordsherbivores; trophic ecology; fire; management; species distribution models
- Click on "Export Reference in RIS Format" and choose "open with... Endnote".
- Click on "Export Reference in RIS Format". Login to Refworks, go to References => Import References