Assessing the geomorphic disturbance from fires on coastal dunes near Esperance, Western Australia: Implications for dune de-stabilisation

Shumack, Samuel; Hesse, Paul

doi:10.1016/j.aeolia.2017.08.005

Cited by 15 publications

(21 citation statements)

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“…Fire is rarely suggested as a mechanism responsible for blowout activation as the fires generally will not entirely remove vegetation, and the burnt trees/shrubs can still protect the sand surface from wind exposure (Shumack and Hesse, 2018; Shumack et al, 2017). The vegetation surrounding the Carlo Blowout, however, is dense sclerophyll woodland dominated by Eucalyptus and Corymbia , which can produce large, very intense fires because of forest structure and high amounts of biomass (fuel load) (Price and Gordon, 2016; Prior et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

“…Recent studies by Shumack et al (2017) and Shumack and Hesse (2018) that investigated the effect of fire on the destabilisation of coastal dunes found that in Western Australia, fire alone does not lead to dune destabilisation. They do, however, suggest that fires will increase the susceptibility of a sand body to other disturbances.…”

Section: Discussionmentioning

confidence: 99%

“…The vegetation within their study areas, however, was dominated by coastal heath which has a lower biomass than Eucalyptus/Corymbia woodland and a shallower soil depth (organic layer) compared with the Carlo Sand Blow region. Because of the increased fuel load and greater soil depth, it is possible that a fire event would be more intense than the study area of Shumack and Hesse (2018). At Carlo, an intense fire could remove a significant portion of sand binding vegetation, inhibiting regrowth; and coupled with a large sediment supply and high sand DP (Figure 5), the sand surface could remain bare for some time.…”

Section: Discussionmentioning

confidence: 99%

“…They do, however, suggest that fires will increase the susceptibility of a sand body to other disturbances. Shumack and Hesse (2018) observed that at one of their sites which experienced a severe burn, short-term (2 months) vegetation regrowth did not occur compared with another site which experienced a more moderate burn. They suggest that intense fires may destroy the seed bank and inhibit short-term recolonisation and regrowth.…”

Section: Blowout Activation and Maintenancementioning

confidence: 94%

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Late-Holocene cliff-top blowout activation and evolution in the Cooloola Sand Mass, south-east Queensland, Australia

et al. 2018

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Cliff-top dunes are a locally important geomorphic features of sedimentary coasts. They are traditionally interpreted as being sourced by (or with) sand derived from the beach below the cliff. This paper presents the results of a stratigraphic and geochronological study of Carlo Sand Blow, a coastal blowout that has developed on top of a high sandy cliff in the Cooloola Sand Mass, southeast Queensland. We use a combination of sedimentological, pedological and geophysical techniques along with optically stimulated luminescence dating to determine the depositional history and evolution of the blowout. We demonstrate that the blowout is dominantly nourished by sand eroded from its floor rather than the adjacent beach. The original dune surface dates to the first half of the last glacial period (c. 40-70 ka) and this dune was deflated in the late-Holocene. Dune activity is directly associated with cliff undercutting because of coastal retreat in the late-Holocene, but coastal erosion on its own is not capable of maintaining aeolian activity. Blowout activity occurred between 2.6 and 2.3 ka and again at 0.3 ka with aeolian sand burying palaeosols. Both soil surfaces contained charcoal and tree stumps in growth position and our study suggests that fire is the immediate trigger for blowout reactivation. It is likely that these fires were anthropogenic in origin, because the site is somewhat protected from natural fire and the ages coincide with intensification of human use of coastal sites in the area.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Blowout Activation and Maintenancementioning

confidence: 94%

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Late-Holocene cliff-top blowout activation and evolution in the Cooloola Sand Mass, south-east Queensland, Australia

et al. 2018

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“…Classification thresholds have been established with comparisons to in situ observations and methods such as the Composite Burn Index (CBI) [27,28], but are limited to the region and vegetation community for which they are optimised [29]. Two of the most commonly used indices that are used to map the extent of burnt area and fire severity are the normalised burn ratio (NBR) and the normalised difference vegetation index (NDVI) [30][31][32][33] that combine the shortwave infrared (SWIR), near-infrared (NIR), or red spectral bands of the electromagnetic (EM) spectrum. These bands are ideal for monitoring vegetation dynamics as the NIR wavelengths shows greenness and chlorophyl concentration, whereas the SWIR wavelengths are sensitive to water content and woody biomass [16,34].…”

Section: Introductionmentioning

confidence: 99%

A New Application of the Disturbance Index for Fire Severity in Coastal Dunes

et al. 2021

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Fires are a disturbance that can lead to short term dune destabilisation and have been suggested to be an initiation mechanism of a transgressive dune phase when paired with changing climatic conditions. Fire severity is one potential factor that could explain subsequent coastal dune destabilisations, but contemporary evidence of destabilisation following fire is lacking. In addition, the suitability of conventional satellite Earth Observation methods to detect the impacts of fire and the relative fire severity in coastal dune environments is in question. Widely applied satellite-derived burn indices (Normalised Burn Index and Normalised Difference Vegetation Index) have been suggested to underestimate the effects of fire in heterogenous landscapes or areas with sparse vegetation cover. This work assesses burn severity from high resolution aerial and Sentinel 2 satellite imagery following the 2019/2020 Black Summer fires on Kangaroo Island in South Australia, to assess the efficacy of commonly used satellite indices, and validate a new method for assessing fire severity in coastal dune systems. The results presented here show that the widely applied burn indices derived from NBR differentially assess vegetation loss and fire severity when compared in discrete soil groups across a landscape that experienced a very high severity fire. A new application of the Tasselled Cap Transformation (TCT) and Disturbance Index (DI) is presented. The differenced Disturbance Index (dDI) improves the estimation of burn severity, relative vegetation loss, and minimises the effects of differing soil conditions in the highly heterogenous landscape of Kangaroo Island. Results suggest that this new application of TCT is better suited to diverse environments like Mediterranean and semi-arid coastal regions than existing indices and can be used to better assess the effects of fire and potential remobilisation of coastal dune systems.

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Changes in the vegetation cover of transgressive dune fields: A case study in Cape Woolamai, Victoria

Gao

Kennedy

Konlechner

et al. 2021

Earth Surf Processes Landf

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Changes in vegetation cover and dune mobility of Woolamai dune fields on the southeast coast of Australia were quantified based on a time series of aerial imagery (1939 to 2020). Results showed that the dune fields have shifted from nearly all bare sand (with <5% vegetation cover) to a new quasi‐equilibrium state, being almost fully stabilized by vegetation (>80%) from 1939 to 2020. Three temporal stages of vegetation change were identified, namely: (I) early expansion over 1939–1975; (II) rapid growth from 1976 to 2010; and (III) recent ‘quasi‐equilibrium’ state in 2010–2020. In stage I, complex impacts of climate and human activities co‐existed with uncertainty of the dominant factor. In this early stage, vegetation growth was constrained to the low and sheltered areas, indicating the influence of topography. Rapid vegetation growth took place in 1976–2010 (stage II), during which a re‐vegetation programme combined with favourable climate conditions promoted vegetation growth. In the last decade (stage III), vegetation might have reached a new quasi‐equilibrium when the vegetation almost reached a maximum. The slight loss of vegetation could be attributed to weed control and an unfavourable climate for growth (drier and windier) in Woolamai dune fields. This study showed that variations in vegetation cover and dune mobility through time are not simply linked to a single factor but depend on the occurrence of multiple factors (e.g. topography, climate and human activities) that promote stability, or alternatively, mobility of the dune system. This research contributes to expanding our understanding of the complexity of the bio‐geomorphologic dynamics in dune fields. It also provides detailed observational evidence for the historical trajectory of vegetation expansion from the bare dune fields to a fully stabilized state, which can be used to verify and refine models for other similar dune sites.

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Assessing the geomorphic disturbance from fires on coastal dunes near Esperance, Western Australia: Implications for dune de-stabilisation

Cited by 15 publications

References 80 publications

Late-Holocene cliff-top blowout activation and evolution in the Cooloola Sand Mass, south-east Queensland, Australia

Late-Holocene cliff-top blowout activation and evolution in the Cooloola Sand Mass, south-east Queensland, Australia

A New Application of the Disturbance Index for Fire Severity in Coastal Dunes

Changes in the vegetation cover of transgressive dune fields: A case study in Cape Woolamai, Victoria

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