Effects of burn severity on organic nitrogen and carbon chemistry in high-elevation forest soils

Holly K. Roth; Amy M. McKenna; Myrna J. Simpson; Huan Chen; Nivetha Srikanthan; Timothy S. Fegel; Amelia R. Nelson; Charles C. Rhoades; Michael J. Wilkins; Thomas Borch

doi:10.1016/j.seh.2023.100023

Effects of burn severity on organic nitrogen and carbon chemistry in high-elevation forest soils

Holly K. Roth
, Amy M. McKenna
, Myrna J. Simpson
, Huan Chen
, Nivetha Srikanthan
, Timothy S. Fegel
, Amelia R. Nelson
, Charles C. Rhoades
, Michael J. Wilkins
, Thomas Borch

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

Fire frequency and severity have increased in recent decades in the western United States, with direct implications for the quantity and composition of soil organic matter (SOM). While the effects of wildfire on soil carbon (C) and inorganic nitrogen (N) have been well studied, little is known about its impacts on soil organic N. Since organic N is the most abundant form of soil N in conifer forests and dominant source of plant N facilitated by symbiotic mycorrhizae and mineralization, better understanding of post-fire organic N chemistry will help address a critical gap in our understanding of fire effects on SOM. Here, we characterized changes to organic N chemistry across fire severity gradients resulting from two wildfires that burned lodgepole pine (Pinus contorta) forest along the Colorado/Wyoming border, USA. One representative gradient was selected for high-resolution analysis based on results from bulk data (total C and N, and pH). Mineral soils were collected from two depths in low, moderate, and high severity burned areas and adjacent, unburned locations one year following the Ryan and Badger Creek fires. Nuclear magnetic resonance spectroscopy and 21 tesla ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry analysis showed that N content and aromaticity of water-extractable SOM (0–5 cm depth) increased with burn severity, while minimal changes to 5–10 cm depth were observed. Heterocyclic N species are generally higher in toxicity compared to their non-nitrogenated counterparts, which prompted soil toxicity measurements. Complementary Microtox® analysis revealed a positive relationship between increased fire severity and increased soil toxicity to Aliivibrio fischeri (microbial test species). These findings add to our molecular-level understanding of organic C and N responses to wildfire severity, with likely implications for nutrient cycling, forest recovery and water quality following severe wildfire.

Original language	English
Article number	100023
Journal	Soil and Environmental Health
Volume	1
Issue number	3
DOIs	https://doi.org/10.1016/j.seh.2023.100023
State	Published - Sep 2023
Externally published	Yes

Funding

DOC and DTN measurements were conducted at the Rocky Mountain Research Station, biogeochemistry laboratory, courtesy of the USDA Forest Service. The authors acknowledge support of MJW and TB from the National Science Foundation under grant number 2114868 and USDA National Institute of Food and Agriculture through AFRI grant number 2021-67019-34608. A portion of the work was performed at the National High Magnetic Field Laboratory ICR User Facility, which is supported by the National Science Foundation Division of Chemistry and Division of Material Research through DMR-1644779 and the State of Florida. M.J.S. thanks the Natural Sciences and Engineering Research Council ( NSERC ) of Canada for support via a Discovery Grant and the Tier 1 Canada Research Chair in Integrative Molecular Biogeochemistry. DOC and DTN measurements were conducted at the Rocky Mountain Research Station, biogeochemistry laboratory, courtesy of the USDA Forest Service. The authors acknowledge support of MJW and TB from the National Science Foundation under grant number 2114868 and USDA National Institute of Food and Agriculture through AFRI grant number 2021-67019-34608. A portion of the work was performed at the National High Magnetic Field Laboratory ICR User Facility, which is supported by the National Science Foundation Division of Chemistry and Division of Material Research through DMR-1644779 and the State of Florida. M.J.S. thanks the Natural Sciences and Engineering Research Council (NSERC) of Canada for support via a Discovery Grant and the Tier 1 Canada Research Chair in Integrative Molecular Biogeochemistry.

Keywords

FT-ICR MS
Heterocyclic N
Microtox toxicity
NMR spectroscopy
Soil organic matter
Wildfire severity gradients

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10.1016/j.seh.2023.100023

Cite this

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title = "Effects of burn severity on organic nitrogen and carbon chemistry in high-elevation forest soils",

abstract = "Fire frequency and severity have increased in recent decades in the western United States, with direct implications for the quantity and composition of soil organic matter (SOM). While the effects of wildfire on soil carbon (C) and inorganic nitrogen (N) have been well studied, little is known about its impacts on soil organic N. Since organic N is the most abundant form of soil N in conifer forests and dominant source of plant N facilitated by symbiotic mycorrhizae and mineralization, better understanding of post-fire organic N chemistry will help address a critical gap in our understanding of fire effects on SOM. Here, we characterized changes to organic N chemistry across fire severity gradients resulting from two wildfires that burned lodgepole pine (Pinus contorta) forest along the Colorado/Wyoming border, USA. One representative gradient was selected for high-resolution analysis based on results from bulk data (total C and N, and pH). Mineral soils were collected from two depths in low, moderate, and high severity burned areas and adjacent, unburned locations one year following the Ryan and Badger Creek fires. Nuclear magnetic resonance spectroscopy and 21 tesla ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry analysis showed that N content and aromaticity of water-extractable SOM (0–5 cm depth) increased with burn severity, while minimal changes to 5–10 cm depth were observed. Heterocyclic N species are generally higher in toxicity compared to their non-nitrogenated counterparts, which prompted soil toxicity measurements. Complementary Microtox{\textregistered} analysis revealed a positive relationship between increased fire severity and increased soil toxicity to Aliivibrio fischeri (microbial test species). These findings add to our molecular-level understanding of organic C and N responses to wildfire severity, with likely implications for nutrient cycling, forest recovery and water quality following severe wildfire.",

keywords = "FT-ICR MS, Heterocyclic N, Microtox toxicity, NMR spectroscopy, Soil organic matter, Wildfire severity gradients",

author = "Roth, \{Holly K.\} and McKenna, \{Amy M.\} and Simpson, \{Myrna J.\} and Huan Chen and Nivetha Srikanthan and Fegel, \{Timothy S.\} and Nelson, \{Amelia R.\} and Rhoades, \{Charles C.\} and Wilkins, \{Michael J.\} and Thomas Borch",

note = "Publisher Copyright: {\textcopyright} 2023 The Author(s)",

year = "2023",

month = sep,

doi = "10.1016/j.seh.2023.100023",

language = "English",

volume = "1",

journal = "Soil and Environmental Health",

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TY - JOUR

T1 - Effects of burn severity on organic nitrogen and carbon chemistry in high-elevation forest soils

AU - Roth, Holly K.

AU - McKenna, Amy M.

AU - Simpson, Myrna J.

AU - Chen, Huan

AU - Srikanthan, Nivetha

AU - Fegel, Timothy S.

AU - Nelson, Amelia R.

AU - Rhoades, Charles C.

AU - Wilkins, Michael J.

AU - Borch, Thomas

PY - 2023/9

Y1 - 2023/9

N2 - Fire frequency and severity have increased in recent decades in the western United States, with direct implications for the quantity and composition of soil organic matter (SOM). While the effects of wildfire on soil carbon (C) and inorganic nitrogen (N) have been well studied, little is known about its impacts on soil organic N. Since organic N is the most abundant form of soil N in conifer forests and dominant source of plant N facilitated by symbiotic mycorrhizae and mineralization, better understanding of post-fire organic N chemistry will help address a critical gap in our understanding of fire effects on SOM. Here, we characterized changes to organic N chemistry across fire severity gradients resulting from two wildfires that burned lodgepole pine (Pinus contorta) forest along the Colorado/Wyoming border, USA. One representative gradient was selected for high-resolution analysis based on results from bulk data (total C and N, and pH). Mineral soils were collected from two depths in low, moderate, and high severity burned areas and adjacent, unburned locations one year following the Ryan and Badger Creek fires. Nuclear magnetic resonance spectroscopy and 21 tesla ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry analysis showed that N content and aromaticity of water-extractable SOM (0–5 cm depth) increased with burn severity, while minimal changes to 5–10 cm depth were observed. Heterocyclic N species are generally higher in toxicity compared to their non-nitrogenated counterparts, which prompted soil toxicity measurements. Complementary Microtox® analysis revealed a positive relationship between increased fire severity and increased soil toxicity to Aliivibrio fischeri (microbial test species). These findings add to our molecular-level understanding of organic C and N responses to wildfire severity, with likely implications for nutrient cycling, forest recovery and water quality following severe wildfire.

AB - Fire frequency and severity have increased in recent decades in the western United States, with direct implications for the quantity and composition of soil organic matter (SOM). While the effects of wildfire on soil carbon (C) and inorganic nitrogen (N) have been well studied, little is known about its impacts on soil organic N. Since organic N is the most abundant form of soil N in conifer forests and dominant source of plant N facilitated by symbiotic mycorrhizae and mineralization, better understanding of post-fire organic N chemistry will help address a critical gap in our understanding of fire effects on SOM. Here, we characterized changes to organic N chemistry across fire severity gradients resulting from two wildfires that burned lodgepole pine (Pinus contorta) forest along the Colorado/Wyoming border, USA. One representative gradient was selected for high-resolution analysis based on results from bulk data (total C and N, and pH). Mineral soils were collected from two depths in low, moderate, and high severity burned areas and adjacent, unburned locations one year following the Ryan and Badger Creek fires. Nuclear magnetic resonance spectroscopy and 21 tesla ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry analysis showed that N content and aromaticity of water-extractable SOM (0–5 cm depth) increased with burn severity, while minimal changes to 5–10 cm depth were observed. Heterocyclic N species are generally higher in toxicity compared to their non-nitrogenated counterparts, which prompted soil toxicity measurements. Complementary Microtox® analysis revealed a positive relationship between increased fire severity and increased soil toxicity to Aliivibrio fischeri (microbial test species). These findings add to our molecular-level understanding of organic C and N responses to wildfire severity, with likely implications for nutrient cycling, forest recovery and water quality following severe wildfire.

KW - FT-ICR MS

KW - Heterocyclic N

KW - Microtox toxicity

KW - NMR spectroscopy

KW - Soil organic matter

KW - Wildfire severity gradients

UR - https://www.scopus.com/pages/publications/85181896652

U2 - 10.1016/j.seh.2023.100023

DO - 10.1016/j.seh.2023.100023

M3 - Article

AN - SCOPUS:85181896652

SN - 2949-9194

VL - 1

JO - Soil and Environmental Health

JF - Soil and Environmental Health

IS - 3

M1 - 100023

ER -

Effects of burn severity on organic nitrogen and carbon chemistry in high-elevation forest soils

Abstract

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Keywords

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