Catchment characteristics modulate the influence of wildfires on nitrate and dissolved organic carbon across space and time: A meta-analysis

Cavaiani, Jake; Regier, Peter; Roebuck, Jesse Alan; Barnes, Morgan; Garayburu-Caruso, Vanessa; Gillespie, Xia; McKever, Sophia; Renteria, Lupita; Myers-Pigg, Allison

doi:10.22541/essoar.171052482.22663736/v1

Cited by 3 publications

(1 citation statement)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Soil organic carbon quality and concentration strongly influence the mobilization of f.THg from forested catchments − and are affected by fires in complex ways . For example, pyromorphic humus or black carbonrecalcitrant types of organic matter formed during firescan sequester f.THg through complexation, thereby reducing f.THg mobilization. ,,, Similarly, the effect of fires on stream DOC is complex and often dependent on local catchment and climatic conditions, with studies reporting increased, decreased, or unchanged DOC concentrations following wildfires, particularly among smaller headwater streams. ,− This variability in the observed effects of wildfire on DOC likely also reflects differences in the timing of sampling among studies and the strong temporal patterns in DOC mobilization following the wildfire. High temporal resolution studies have shown that DOC concentrations in wildfire-affected streams typically increase in the short term (i.e., months post fire), but often decline over the medium term, with the time needed to see these changes influenced by fire severity, watershed characteristics, and precipitation events. − Because DOC plays a critical role in regulating Hg transport from watersheds to headwater streams, − the temporal variability in DOC responses to wildfire are likely to have implications for Hg cycling that are not fully represented by short-term studies.…”

Section: Discussionmentioning

confidence: 99%

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest

Baldwin,

Willacker,

Johnson

et al. 2024

Environ. Sci. Technol.

View full text Add to dashboard Cite

The increasing frequency and severity of wildfires are among the most visible impacts of climate change. However, the effects of wildfires on mercury (Hg) transformations and bioaccumulation in stream ecosystems are poorly understood. We sampled soils, water, sediment, in-stream leaf litter, periphyton, and aquatic invertebrates in 36 burned (one-year post fire) and 21 reference headwater streams across the northwestern U.S. to evaluate the effects of wildfire occurrence and severity on total Hg (THg) and methylmercury (MeHg) transport and bioaccumulation. Suspended particulate THg and MeHg concentrations were 89 and 178% greater in burned watersheds compared to unburned watersheds and increased with burn severity, likely associated with increased soil erosion. Concentrations of filter-passing THg were similar in burned and unburned watersheds, but filter-passing MeHg was 51% greater in burned watersheds, and suspended particles in burned watersheds were enriched in MeHg but not THg, suggesting higher MeHg production in burned watersheds. Among invertebrates, MeHg in grazers, filter-feeders, and collectors was 33, 48, and 251% greater in burned watersheds, respectively, but did not differ in shredders or predators. Thus, increasing wildfire frequency and severity may yield increased MeHg production, mobilization, and bioaccumulation in headwaters and increased transport of particulate THg and MeHg to downstream environments.

show abstract

Section: Discussionmentioning

confidence: 99%

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest

Baldwin,

Willacker,

Johnson

et al. 2024

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

Longitudinal propagation of aquatic disturbances following the largest wildfire recorded in New Mexico, USA

Nichols,

Joseph,

Kaphle

et al. 2024

Nat Commun

View full text Add to dashboard Cite

The influence of burn severity on dissolved organic carbon concentrations across a stream network differs based on seasonal wetness conditions

Wampler,

Bladon,

Myers-Pigg

2024

Biogeosciences

View full text Add to dashboard Cite

Abstract. Large, high-severity wildfires in many regions across the globe have increased concerns about their impacts on carbon cycling in watersheds. Altered sources of carbon and changes in catchment hydrology after wildfire can lead to shifts in dissolved organic carbon (DOC) concentrations in streams, which can have negative impacts on aquatic ecosystem health and downstream drinking-water treatment. Despite its importance, post-fire DOC responses remain relatively unconstrained in the literature, and we lack critical knowledge of how burn severity, landscape elements, and climate interact to affect DOC concentrations. To improve our understanding of the impact of burn severity on DOC concentrations, we measured DOC at 129 sites across a stream network extending upstream, within, and downstream of a large, high-severity wildfire in Oregon, USA. We collected samples across the study sub-basin during four distinct seasonal wetness conditions. We used our high-spatial-resolution data to develop spatial stream network (SSN) models to predict DOC across the stream network and to improve our understanding of the controls on DOC concentrations. Spatially, we found no obvious wildfire signal – instead, we observed a pattern of increasing DOC concentrations from the high-elevation headwaters to the sub-basin outlet, while the mainstem maintained consistently low DOC concentrations. This suggests that effects from large wildfires may be “averaged” out at higher stream orders and larger spatial scales. When we grouped DOC concentrations by burn severity group, we observed a significant decrease in the variability of DOC concentrations in the moderate and high burn severity sub-catchments. However, our SSN models were able to predict decreases in DOC concentrations with increases in burn severity across the stream network. Decreases in DOC concentrations were also highly variable across seasonal wetness conditions, with the greatest (−1.40 to −1.64 mg L−1) decrease occurring in the high-severity group during the wetting season. Additionally, our models indicated that in all seasons, baseflow index was more influential in predicting DOC concentrations than burn severity was, indicating that groundwater discharge can obscure the impacts of wildfire in a stream network. Overall, our results suggested that landscape characteristics can regulate the DOC response to wildfire. Moreover, our results also indicated that the seasonal timing of sampling can influence the observed response of DOC concentrations to wildfire.

show abstract

Catchment characteristics modulate the influence of wildfires on nitrate and dissolved organic carbon across space and time: A meta-analysis

Cited by 3 publications

References 64 publications

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest

Wildfires Influence Mercury Transport, Methylation, and Bioaccumulation in Headwater Streams of the Pacific Northwest

Longitudinal propagation of aquatic disturbances following the largest wildfire recorded in New Mexico, USA

The influence of burn severity on dissolved organic carbon concentrations across a stream network differs based on seasonal wetness conditions

Contact Info

Product

Resources

About