Linking wildfire effects on soil and water chemistry of the Marão River watershed, Portugal, and biomass changes detected from Landsat imagery

Costa, Maria do Rosário; Calvão, Ana Rita; Aranha, José

doi:10.1016/j.apgeochem.2013.09.009

Cited by 55 publications

(43 citation statements)

References 35 publications

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“…The lower pH values found here could be related to the fact that sampling was not carried out immediately after the fire. Costa et al (2014) also recorded relatively low pH values of $ 6 in ash collected five months after a wildfire in Portugal. Temporal evolution of wildfire ash can lead to hydrationcarbonation reactions of oxides and formation of carbonates , which are less reactive and soluble (Santos et al, 2009;Pan et al, 2012).…”

Section: Physicochemical Characteristics Of the Water-soluble Fractiomentioning

confidence: 90%

“…This highly erodible material can be rapidly mobilised both by wind and water erosion and transferred into water bodies. Ash quantity and composition is very variable, but overall, ash-derived nutrients and minor elements can have a major impact on water quality Costa et al, 2014). Although wildfire ash is generally more erodible than soil due to its loose nature and lower bulk density, it is usually not examined as a distinct part of the sediment transported by wind and water erosion, and its associated water contamination potential has rarely been investigated (Bodí et al, 2014).…”

Section: Introductionmentioning

confidence: 98%

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Quantity, composition and water contamination potential of ash produced under different wildfire severities

Santín

Doerr

Otero

et al. 2015

Environmental Research

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Wildfires frequently threaten water quality through the transfer of eroded ash and soil into rivers and reservoirs. The ability to anticipate risks for water resources from wildfires is fundamental for implementing effective fire preparedness plans and post-fire mitigation measures. Here we present a new approach that allows quantifying the amount and characteristics of ash generated under different wildfire severities and its respective water contamination potential. This approach is applied to a wildfire in an Australian dry sclerophyll eucalypt forest, but can be adapted for use in other environments. The Balmoral fire of October 2013 affected 12,694 ha of Sydney's forested water supply catchment. It produced substantial ash loads that increased with fire severity, with 6, 16 and 34 Mg ha(-1) found in areas affected by low, high and extreme fire severity, respectively. Ash bulk density was also positively related to fire severity. The increase with fire severity in the total load and bulk density of the ash generated is mainly attributed to a combination of associated increases in (i) total amount of fuel affected by fire and (ii) contribution of charred mineral soil to the ash layer. Total concentrations of pollutants and nutrients in ash were mostly unrelated to fire severity and relatively low compared to values reported for wildfire ash in other environments (e.g. 4.0-7.3mg As kg(-1); 2.3-4.1 B mg kg(-1); 136-154 P mg kg(-1)). Solubility of the elements analysed was also low, less than 10% of the total concentration for all elements except for B (6-14%) and Na (30-50%). This could be related to a partial loss of soluble components by leaching and/or wind erosion before the ash sampling (10 weeks after the fire and before major ash mobilisation by water erosion). Even with their relatively low concentrations of potential pollutants, the substantial total ash loads found here represent a water contamination risk if transported into the hydrological network during severe erosion events. For example, up to 4 Mg of ash-derived P could be delivered into a single water supply reservoir.

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Section: Physicochemical Characteristics Of the Water-soluble Fractiomentioning

confidence: 90%

Section: Introductionmentioning

confidence: 98%

Quantity, composition and water contamination potential of ash produced under different wildfire severities

Santín

Doerr

Otero

et al. 2015

Environmental Research

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“…Both present major biological concern owing to their carcinogenic potential, persistence within ecosystems and tendency to bio-accumulate (Smith et al 2011;Chen et al 2018). These contaminants are thought to have complex impacts on water quality and the biological effects of these in aquatic systems have been observed to persist across long spatial and temporal scales (Earl and Blinn 2003;Costa et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Chemical composition of wildfire ash produced in contrasting ecosystems and its toxicity to Daphnia magna

Harper

Santín

Doerr

et al. 2019

Int. J. Wildland Fire

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It is well established in the world’s fire-prone regions that wildfires can considerably change the hydrological dynamics of freshwater catchments. Limited research, however, has focused on the potential impacts of wildfire ash toxicity on aquatic biota. Here, we assess the chemical composition and toxicity of ash generated from wildfires in six contrasting vegetation types distributed globally (UK grassland, Spanish pine forest, Spanish heathland, USA chaparral, Australian eucalypt forest and Canadian spruce forest). Acute (48h) immobilisation tests were conducted on the extensively studied aquatic macroinvertebrate Daphnia magna, a sensitive indicator of aquatic contaminants. We found significant differences between the chemical composition and toxicity of these ash types. The UK and Spanish ash had no detectable toxicity to Daphnia magna, whereas the Australian eucalypt, USA chaparral and Canadian spruce ash all caused significant toxicity (immobilisation). The principal characteristics of the latter ash types were their high pH, and NO3−, Cl− and conductivity levels. Elevated water-soluble and total concentrations of metals (e.g. Mn, Fe, Zn, Pb, Cu and As) and total polycyclic aromatic hydrocarbons (PAHs) were not linked to toxicity.

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“…Afforestation is generally expected to improve the provision of hydrological services, especially flood mitigation, soil erosion protection and water quality regulation, at the expense of decreasing water availability (Bredemeier, 2011;Carvalho-Santos et al, 2014;Keesstra et al, 2009). However, Mediterranean afforestation has also increased the frequency and severity of wildfires (Fernandes et al, 2014;Pausas et al, 2008;Shakesby, 2011), which may potentially increase surface runoff production and soil degradation (Moody et al, 2013;Pausas et al, 2008;Shakesby, 2011) and contaminate streams with toxic compounds in ashes (Bodí et al, 2014;Costa et al, 2014;Verkaik et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Afforestation, Subsequent Forest Fires and Provision of Hydrological Services: A Model‐Based Analysis for a Mediterranean Mountainous Catchment

et al. 2017

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Mediterranean landscapes have experienced extensive abandonment and reforestation in recent decades, which should have improved the provision of hydrological services such as flood mitigation, soil erosion protection and water quality regulation. However, these forests are fire‐prone, and the postfire increase in runoff, erosion and sediment exports could negatively affect service provision. This issue was assessed by using the Soil and Water Assessment Tool model for the Macieira de Alcôba mountain catchment in northwestern Portugal, covered by agriculture and forest plantations, monitored in 2010–2014 and partially burnt in 2011. The model was validated for streamflow, sediment yield and erosion in agricultural fields and burnt hillslopes, showing that it can be adapted for postfire simulation. Model results for a decadal assessment (2004–2014) show that the fire increased erosion in the burnt slopes from 0.1 to 46.5 Mg ha−1 y−1 and catchment sediment yield from 0.14 to 2.1 Mg ha−1 y−1. Erosion in the burnt forest during this decade was 1 order of magnitude above that in agricultural fields. Model results for different fire and land‐use scenarios indicate that postfire erosion and sediment yield were lower without postfire soil management for reforestation and when the fire occurred in pine forests (land use before the 1990s) or in shrublands (land‐use before afforestation in the 1930s). These impacts were robust to changes in postfire weather and to a longer (20 years) unburnt period. The results suggest that, in the long term, Mediterranean fire‐prone forests might not provide the anticipated soil protection and water quality regulation services. Copyright © 2017 John Wiley & Sons, Ltd.

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Linking wildfire effects on soil and water chemistry of the Marão River watershed, Portugal, and biomass changes detected from Landsat imagery

Cited by 55 publications

References 35 publications

Quantity, composition and water contamination potential of ash produced under different wildfire severities

Quantity, composition and water contamination potential of ash produced under different wildfire severities

Chemical composition of wildfire ash produced in contrasting ecosystems and its toxicity to Daphnia magna

Afforestation, Subsequent Forest Fires and Provision of Hydrological Services: A Model‐Based Analysis for a Mediterranean Mountainous Catchment

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