Water-quality impacts from climate-induced forest die-off

Mikkelson, Kristin M.; Dickenson, Eric; Maxwell, R. M.; McCray, John E.; Sharp, Jonathan O.

doi:10.1038/nclimate1724

Cited by 80 publications

(85 citation statements)

References 26 publications

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“…16 For example, drinking water quality was affected by changes in dissolved organic carbon (DOC) and DBP formation attributed to bark-beetle-caused tree mortality in the forest watershed. 17 Compared to such chronic change by forest die-off, wildfire causes a more intensive, acute, and long-term forest mortality that is recognized as one of the strongest natural disturbances. 18 The combustion losses of organic-rich soil horizons and vegetation biomass may reduce the amount of DOC exported from detritus materials.…”

Section: ■ Introductionmentioning

confidence: 99%

Wildfire Altering Terrestrial Precursors of Disinfection Byproducts in Forest Detritus

Wang

Dahlgren

Erşan

et al. 2015

Environ. Sci. Technol.

103

105

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Wildfire occurrence and intensity are increasing worldwide causing severe disturbances to forest watersheds used for potable water supply. The effects of wildfire on drinking water quality are not well understood, especially in terms of terrestrial dissolved organic matter (DOM) and DOM-associated formation of disinfection byproducts (DBP). As the forest floor layer is a major source of terrestrial DOM, we investigated characteristics and DBP formation of water extractable organic matter (WEOM) from the 0−5 cm depth of nonburned detritus (control) and burned detritus with black ash (moderate severity) and white ash (high severity) associated with the 2013 Rim Fire in California. Spectroscopic results suggested that the aromaticity of WEOM followed white ash > control > black ash and fluorescence region II (excitation 220−250 nm; emission 330−380 nm) of the emission-excitation-matrix was identified as a potential burn severity indicator. Compared to the control, WEOM from white and black ashes had lower reactivity in forming trihalomethanes (55%-of-control) and haloacetic acids (67%-of-control), but higher reactivity in forming the more carcinogenic haloacetonitrile after chlorination (244%-of-control) and N-nitrosodimethylamine after chloramination (229%-of-control). There was no change in reactivity for chloral hydrate formation, while WEOM from black ash showed a higher reactivity for haloketone formation (150%-of-control). Because wildfire consumed a large portion of organic matter from the detritus layer, there was lower water extractable organic carbon (27%-of-control) and organic nitrogen (19%-of-control) yields in ashes. Consequently, the wildfire caused an overall reduction in water extractable terrestrial DBP precursor yield from detritus materials.

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Section: ■ Introductionmentioning

confidence: 99%

Wildfire Altering Terrestrial Precursors of Disinfection Byproducts in Forest Detritus

Wang

Dahlgren

Erşan

et al. 2015

Environ. Sci. Technol.

103

105

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“…10,11 Safe drinking water is an important demand for public health, 12,13 but drinking water quality (e.g., DOM and disinfection byproducts (DBPs)) is very sensitive to landscape/ecosystem changes as affected by changing climate and natural/anthropogenic disturbances. 14, 15 Recent case studies revealed that forest fires alter DOM chemistry and thus DBP formation in drinking water, such as the possibly carcinogenic trihalomethanes (THMs), haloacetic acids (HAAs), and haloacetonitriles (HANs). 16−18 With greater wildfire severity, wildfires can potentially decrease the reactivity of terrestrial DOM in forming carbonaceous DBPs such as USEPA-regulated THMs and HAAs but increase the reactivity for forming more carcinogenic nitrogenous DBPs such as HANs and Nnitrosodimethylamine and brominated DBPs such as dichlorobromomethane.…”

Section: ■ Introductionmentioning

confidence: 99%

Controlled Burning of Forest Detritus Altering Spectroscopic Characteristics and Chlorine Reactivity of Dissolved Organic Matter: Effects of Temperature and Oxygen Availability

Wang

Dahlgren

Chow

2015

Environ. Sci. Technol.

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Forest fires occur with increasing frequency and severity in the western United States, potentially altering the chemistry and quantity of dissolved organic matter (DOM) and disinfection byproduct (DBP) precursors exported from forested watersheds. However, little is known concerning effects of the fire triangle (heat, oxygen, and fuel) on DOM alteration. Using detritus from Pinus ponderosa and Abies concolor (dominant species in forests in the western United States), we prepared DOM from unburned and burned detritus under hypoxic (pyrolysis) and oxic conditions (thermal oxidation) at 250 and 400°C. DOM characteristics and chlorine reactivity were evaluated by absorption and fluorescence spectroscopy and chlorination-based DBP formation potential tests. Spectroscopic results suggest that burned-detritus extracts had lower molecular weight (reflected by increased E2:E3 and fluorescence index) and divergent aromaticity (reflected by SUVA 254 ) depending on oxygen availability. Temperature and oxygen availability interacted to alter the chlorine reactivity of fire-affected DOM. Increasing temperature from 50 to 400°C resulted in decreased reactivities for trihalomethane and chloral hydrate formation and divergent reactivities for haloacetonitrile formation (unchanged for pyrolysis and increased for oxidation) and haloketone formation (increased for pyrolysis and decreased for oxidation). We demonstrate that DBP precursors in fire-affected forest detritus are highly dependent on temperature and oxygen availability.

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“…Forests in the Western U.S. are experiencing larger wildfire disturbances attributed to warmer temperatures and earlier spring snowmelts [5], with a 60% increase in large fires from the mid-1980s in the Northern Rocky Mountains and significantly greater extents of severe fires in the Southern Rocky Mountains [6]. Furthermore, unprecedented mountain pine beetle (MPB; Dendroctonous ponderosae) outbreaks in Western North America killed >10 Mha of trees over the last 2-3 decades [7,8], with major impacts on water resources [9,10], nutrient cycling [11], and forest carbon storage [12]. These disturbance-caused changes require consideration when assessing global change risks to the stability of forest carbon [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…The extent of post-fire changes in soil geochemistry reflects ecosystem type, burn severity, and fire frequency [27][28][29], all of which are influenced by topography [30]. Forest diebacks driven by MPB outbreaks alter C and N cycling pathways to varying degrees, depending on percent tree mortality [8] and phase of infestation [9,10,31,32], among other factors. The changes in soil biogeochemistry following MPB infestation include greater soil moisture availability likely due to reduced evapotranspiration associated with high tree mortality [33]; a reduction in phosphate (PO 4 3 ) concentrations [34]; lower C/N ratios in the leaf litter compared to little to no change in soil C/N ratios [34]; greater aromaticity of dissolved organic carbon (DOC) [8] and elevated concentrations of NH 4 + in the soil environment given the cessation of nitrogen uptake and more litter available following tree mortality [11,35,36].…”

Section: Introductionmentioning

confidence: 99%

“…Nitrate concentrations following MPB outbreaks vary, with the strongest NO 3 − responses in forests that receive substantial N deposition (e.g., Europe, Asia) compared to N-limited system in Western North America [37][38][39]. Studies of terrain-driven changes in soil biogeochemistry following MPB outbreaks are more limited, yet terrain attributes, such as slope, elevation, and aspect, serve as important factors for modeling hillslope-scale water availability following MPB outbreaks [9,10]. Microbial communities in forested systems demonstrate strong responses to disturbance-driven changes in soil geochemistry and substrate inputs in the months to years following wildfire [40,41] and MPB outbreaks [12,42].…”

Section: Introductionmentioning

confidence: 99%

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Disturbance Alters the Relative Importance of Topographic and Biogeochemical Controls on Microbial Activity in Temperate Montane Forests

Lybrand

Gallery

Trahan

et al. 2018

Forests

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Abstract:Fire and pathogen-induced tree mortality are the two dominant forms of disturbance in Western U.S. montane forests. We investigated the consequences of both disturbance types on the controls of microbial activity in soils from 56 plots across a topographic gradient one year after the 2012 High Park wildfire in Colorado. Topsoil biogeochemistry, soil CO 2 efflux, potential exoenzyme activities, and microbial biomass were quantified in plots that experienced fire disturbance, beetle disturbance, or both fire and beetle disturbance, and in plots where there was no recent evidence of disturbance. Soil CO 2 efflux, N-, and P-degrading exoenzyme activities in undisturbed plots were positively correlated with soil moisture, estimated from a topographic wetness index; coefficient of determinations ranged from 0.5 to 0.65. Conversely, the same estimates of microbial activities from fire-disturbed and beetle-disturbed soils showed little correspondence to topographically inferred wetness, but demonstrated mostly negative relationships with soil pH (fire only) and mostly positive relationships with DOC/TDN (dissolved organic carbon/total dissolved nitrogen) ratios for both disturbance types. The coefficient of determination for regressions of microbial activity with soil pH and DOC/TDN reached 0.8 and 0.63 in fire-and beetle-disturbed forests, respectively. Drivers of soil microbial activity change as a function of disturbance type, suggesting simple mathematical models are insufficient in capturing the impact of disturbance in forests.

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Water-quality impacts from climate-induced forest die-off

Cited by 80 publications

References 26 publications

Wildfire Altering Terrestrial Precursors of Disinfection Byproducts in Forest Detritus

Wildfire Altering Terrestrial Precursors of Disinfection Byproducts in Forest Detritus

Controlled Burning of Forest Detritus Altering Spectroscopic Characteristics and Chlorine Reactivity of Dissolved Organic Matter: Effects of Temperature and Oxygen Availability

Disturbance Alters the Relative Importance of Topographic and Biogeochemical Controls on Microbial Activity in Temperate Montane Forests

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