Fire, herbivores and the management of temperate Eucalyptus savanna in Tasmania: Introducing the Beaufront fire – mammalian herbivore field experiment

Abstract

The temperate Eucalyptus savannas in the Midlands of Tasmania are ancient ecosystems where fire and grazing are intrinsic ecological disturbances. The arrival of Aboriginal people into Tasmania some 40,000 years ago altered natural fire regimes, and since the end of the last ice age, their skilful patch burning increased the grass cover and the abundance of large grazers in the Midlands savannas. This ancient socio-ecological tradition abruptly ended following European invasion in the early 19th century, which resulted in the rapid establishment of pastoralism, causing profound adverse changes to the ecological integrity of the temperate savannas. These changes include widespread tree clearing, extinction of native biota, establishment of domestic and feral mammalian herbivores, the introduction of exotic plants, broadscale application of chemical fertilisers and more recently irrigation. The Midlands retains a small fraction of the original vegetation, which typically occurs in small fragments on private land. These have been colonised by nonnative plants and animals, and experience altered fire regimes. There is a growing awareness that to effectively manage temperate savanna fragments may require the intentional coupling of fire and herbivory. We describe the establishment of a field experiment designed to test four broad hypotheses: a) herbivore off-take increases after fire; b) smaller burned areas experience more intense herbivory than larger ones; c) non-native herbaceous plants are more tolerant of herbivory, whereas native herbaceous species are more tolerant of fire; and d) Eucalyptus seedlings are most likely to reach maturity in areas which are both burned and protected from herbivores. A novel aspect of the fire-herbivore experiment was that the Tasmanian Aboriginal community were engaged with and were contracted to conduct the burning. The findings of this landscape ecology experiment will inform the management of remnant temperate Eucalyptus savannas.

Pyric herbivory in a temperate European wood‐pasture system

“…However, these traditional management methods ignore the spatiotemporal changes and patterns resulting from pyric herbivory, that is, the creation of a shifting mosaic landscape (Briske et al., 2003; Fuhlendorf & Engle, 2001). Fire and herbivory as strongly interacting processes can therefore be considered as potential tools in conservation management to create or increase heterogeneity in vegetation structure and composition in grasslands and other potentially flammable ecosystems (Bowman et al., 2021; Fuhlendorf et al., 2012; McGranahan & Kirkman, 2013; Wilcox et al., 2021).…”

Restoring landscape burning is compatible with conservation and livestock production in a southeast Australian grassland fragment

“…Mean annual rainfall is 489 mm, spread throughout the year (details for the town of Ross; http://www.bom.gov.au/climate/data/). The Midlands were once a mosaic of grasslands and grassy Eucalyptus woodlands; ancient ecosystems maintained by Aboriginal burning for millennia (Bowman et al., 2021). Following European arrival in Tasmania in the early 19th century, the Midlands were targeted for agriculture, and most of the native vegetation was cleared.…”

“…treeless areas) and woodland (i.e. plots with an open tree canopy), targeting flammable vegetation (excluding ~10% of the study area dominated by non‐flammable exotic pasture plants; see Bowman et al., 2021). Three plots with little flammable vegetation during burning were excluded from analyses a priori.…”

“…A single round of burns was conducted between 11 April 2018 and 24 April 2018, under mild fire weather conditions (McArthur's Forest Fire Danger Index rating between 2 and 11; McArthur, 1967). Fires were of low intensity (50–690 kW/m; see Bowman et al., 2021) and were patchy. To maximise the proportion of each plot burnt, areas missed by the initial fire front were ignited separately.…”

Small‐scale fires interact with herbivore feedbacks to create persistent grazing lawn environments

“…For instance, frequent fires applied across large spatial extents can reduce grazing lawn extent and promote tussock grasslands due to the dispersion of post‐fire regrowth and, consequently, grazers, across the landscape. This dispersion allows grasses to escape the ongoing grazing pressure necessary for lawn formation (Archibald et al., 2005; Bowman et al., 2021). In contrast, small scale, patchy fires can concentrate grazing pressure within tall grass areas, initiating a positive feedback loop between fire and grazing and facilitating grazing lawn establishment and persistence (Bond & Archibald, 2003).…”