Australian Savanna Fire Regimes: Context, Scales, Patchiness

Russell‐Smith, Jeremy; Yates, Cameron

doi:10.4996/fireecology.0301048

Cited by 57 publications

(33 citation statements)

References 43 publications

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“…This smaller sink in the understory results from cycads (Watkinson and Powell, 1997) and juvenile overstory species, whose life histories and productivity are tightly linked to fire (as per NEP section) (Murphy et al, 2010;Werner and Franklin, 2010;Werner, 2012). Given that fire frequency in these savannas is every 1-3 years (Russell-Smith and Yates, 2007), it cannot be ignored when considering the temporal dynamics of savanna productivity. Therefore, we argue that whilst light limitation appears to be the primary driver of productivity in the wet season, the inter-annual productivity of these savannas in the dry season appears to be limited by a more complex interaction of water availability for the overstory, particularly in the early dry season, phenology responses of both the understory and overstory to reduced water availability and variability in the occurrence and intensity of fire.…”

Section: Inter-annual Variability In Savanna Fluxesmentioning

confidence: 99%

“…1). Fire is one of the major disturbances in the Howard Springs region, with a recurrence interval of 1-3 years (Russell-Smith and Yates, 2007). Cyclone activity and land use change are other disturbances that are common in the region, but which occur over longer timescales .…”

Section: Site Descriptionmentioning

confidence: 99%

“…Much of the spatial variability in the relative cover fractions of trees and grass is thought to be due to annual rainfall, which defines woody cover and subsequent grass production. The large spatial variation in grass productivity leads to high (1-3 year) fire frequency (Russell-Smith and Yates, 2007;Beringer et al, 2015) that feeds back to control woody plant demographics. Fire typically consumes cured grass biomass, top kills juvenile trees and scorches the bark and leaves of mature canopy trees (Prior et al, 2006;Werner and Franklin, 2010;Werner and Prior, 2013).…”

Section: Introductionmentioning

confidence: 99%

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The contribution of trees and grasses to productivity of an Australian tropical savanna

et al. 2016

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Abstract. Savanna ecosystems cover 20 % of the global land surface and account for 25 % of global terrestrial carbon uptake. They support one fifth of the world's human population and are one of the most important ecosystems on our planet. Savanna productivity is a product of the interplay between trees and grass that co-dominate savanna landscapes and are maintained through interactions with climate and disturbance (fire, land use change, herbivory). In this study, we evaluate the temporally dynamic partitioning of overstory and understory carbon dioxide fluxes in Australian tropical savanna using overstory and understory eddy covariance measurements. Over a 2-year period (September 2012 to October 2014) the overall net ecosystem productivity (NEP) of the savanna was 506.2 (±22 SE) g C m −2 yr −1 . The total gross primary productivity (GPP) was 2267.1 (±80 SE) g C m −2 yr −1 , of which the understory contributed 32 %. The understory contribution was strongly seasonal, with most GPP occurring in the wet season (40 % of total ecosystem in the wet season and 18 % in the dry). This study is the first to elucidate the temporal dynamics of savanna understory and overstory carbon flux components explicitly using observational information. Understanding grass productivity is crucial for evaluating fuel loads, as is tree productivity for quantifying the tree carbon sink. This information will contribute to a significant refinement of the representation of savannas in models, as well as improved understanding of relative tree-grass productivity and competition for resources.

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Section: Inter-annual Variability In Savanna Fluxesmentioning

confidence: 99%

Section: Site Descriptionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The contribution of trees and grasses to productivity of an Australian tropical savanna

et al. 2016

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confidence: 99%

“…This issue is especially relevant in the vast savanna landscapes of northern Australia, where disruptions to traditional Aboriginal burning practices following European settlement have meant that fire has been largely unmanaged over recent decades in many regions. This has led to an increase in the frequency and extent of higher intensity fires occurring late in the dry season, and there are widespread fears that such changed fire regimes have had a negative impact on savanna biodiversity (Russell-Smith & Yates 2007, Yates et al 2008, Russell-Smith et al 2012. Although much of Australia's savanna biota is highly resilient to fire (Andersen & Muller 2000, Corbett et al 2003, Russell-Smith et al 2003, Lawes et al 2011, Radford 2012), a range of taxa are threatened by severe fire regimes, including small mammals (Andersen et al 2005, Burbidge et al 2009, Woinarski et al 2010, late-succession reptiles, and invertebrates (e.g., Trainor & Woinarski 1994, Lowe 1995, Taylor & Fox 2001, Barrow 2009, and obligate seeding plant species that can be eliminated by firereturn intervals less than the time required to reach reproductive maturity (Russell-Smith et al 1998, 2002.…”

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confidence: 99%

The Fire Refuge Value of Patches of a Fire‐Sensitive Tree in Fire‐prone Savannas: Callitris intratropica in Northern Australia

Radford¹,

Andersen

Graham³

et al. 2013

Biotropica

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Patches of fire‐sensitive vegetation often occur within fire‐prone tropical savannas, and are indicative of localized areas where fire regimes are less severe. These may act as important fire refugia for fire‐sensitive biota. The fire‐sensitive tree Callitris intratropica occurs in small patches throughout the fire‐prone northern Australian savannas, and is widely seen as an indicator of low‐severity fire regimes and of good ecosystem health. Here, we address the question: to what extent do Callitris patches act as refuges for other fire‐sensitive biota, and therefore play a broader conservation role? We contrast floral and faunal species composition between Callitris patches and surrounding eucalypt savanna, using three case studies. In the first case study, a floristic analysis of 47 Callitris patches across Western Australia's Kimberley region showed that woody species in these patches were overwhelmingly widespread, fire‐tolerant savanna taxa. No species of special conservation concern occurred disproportionately within Callitris patches. Similarly, there was no concentration of fire‐sensitive fauna or flora in five Callitris patches in the East Kimberley. Finally, there was no difference in ant species composition among 12 Callitris patches and surrounding eucalypt savannas in Kakadu National Park, Northern Territory, and there were no fire‐sensitive ant species in Callitris patches. Our three case studies from throughout the northwestern Australia provide no evidence that Callitris patches act as important refuges for fire‐sensitive flora or fauna within fire‐prone eucalypt savannas. This calls into question the notion that Callitris is a strong indicator of general ecosystem health.

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Measuring savanna woody cover at scale to inform ecosystem restoration

Loewensteiner¹,

Bartolo²,

Whiteside³

et al. 2021

Ecosphere

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The maturity of remote sensing and ecosystem restoration science provides new opportunities to monitor and assess ecosystem indicators at finer resolutions and at suitable scales. A key link in joining these fields is creating a framework to apply these rich datasets to ecosystem restoration projects. Savanna woodland ecosystems have discontinuous tree cover that is an important, but potentially highly variable, structural component of these ecosystems. Woody cover in savannas is also well suited to being measured with remote sensing techniques. We extracted woody cover from a 66-yr time series of aerial imagery covering 1718 ha of mesic savanna ecosystem in northern Australia, adjacent to the Ranger uranium mine and encompassing portions of Kakadu National Park. This ecosystem is proposed as a reference ecosystem that may be used to comparatively assess and monitor restoration trajectories of the mine site in the coming decades. The spatiotemporal patterns of change in woody cover were assessed at spatial extents similar to the mine site. We were able to construct a robust distribution of canopy cover values and associated spatial heterogeneity that can be used to set closure criteria, inform restoration trajectories, and guide monitoring activities for the restored mine site.

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Australian Savanna Fire Regimes: Context, Scales, Patchiness

Cited by 57 publications

References 43 publications

The contribution of trees and grasses to productivity of an Australian tropical savanna

The contribution of trees and grasses to productivity of an Australian tropical savanna

The Fire Refuge Value of Patches of a Fire‐Sensitive Tree in Fire‐prone Savannas: Callitris intratropica in Northern Australia

Measuring savanna woody cover at scale to inform ecosystem restoration

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