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Soil nitrogen dynamics three years after a severe Araucaria-Nothofagus forest fire

(2012) AUSTRAL ECOLOGY. 37(2). p.153-163
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Abstract
Wildfires have shaped the biogeography of south Chilean AraucariaNothofagus rainforest vegetation patterns, but their impact on soil properties and associated nutrient cycling remains unclear. Nitrogen (N) availability shows a site-specific response to wildfire events indicating the need for an increased understanding of underlying mechanisms that drive changes in soil N cycling. In this study, we selected unburned and burned sites in a large area of the National Park Tolhuaca that was affected by a stand-replacing wildfire in February 2002. We conducted net N cycling flux measurements (net ammonification, net nitrification and net N mineralization assays) on soils sampled 3 years after fire. In addition, samples were physically fractionated and natural abundance of C and N, and 13C-NMR analyses were performed. Results indicated that standing inorganic N pools were greater in the burned soil, but that no main differences in net N cycling fluxes were observed between unburned and burned sites. In both sites, net ammonification and net nitrification fluxes were low or negative, indicating N immobilization. Multiple linear regression analyses indicated that soil N cycling could largely be explained by two parameters: light fraction (LF) soil organic matter N content and aromatic Chemical Oxidation Resistant Carbon (CORECarom), a relative measure for char. The LF fraction, a strong NH4+ sink, decreased as a result of fire, while CORECarom increased in the burned soil profile and stimulated NO3- production. The absence of increased total net nitrification might relate to a decrease in heterotrophic nitrification after wildfire. We conclude that (i) wildfire induced a shift in N transformation pathways, but not in total net N mineralization, and (ii) stable isotope measurements are a useful tool to assess post-fire soil organic matter dynamics.
Keywords
CHEMICAL OXIDATION, STABLE-ISOTOPES, NATURAL-ABUNDANCE, MICROBIAL BIOMASS, PONDEROSA PINE, ORGANIC-MATTER, C-13 NMR-SPECTRA, stable isotope, organic matter fractionation, N cycling, Chile, 13C-NMR, Andisol, CONIFER FORESTS, BLACK CARBON, LONG-TERM

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Chicago
Rivas, Y, Dries Huygens, H Knicker, R Godoy, F Matus, and Pascal Boeckx. 2012. “Soil Nitrogen Dynamics Three Years After a Severe Araucaria-Nothofagus Forest Fire.” Austral Ecology 37 (2): 153–163.
APA
Rivas, Y, Huygens, D., Knicker, H., Godoy, R., Matus, F., & Boeckx, P. (2012). Soil nitrogen dynamics three years after a severe Araucaria-Nothofagus forest fire. AUSTRAL ECOLOGY, 37(2), 153–163.
Vancouver
1.
Rivas Y, Huygens D, Knicker H, Godoy R, Matus F, Boeckx P. Soil nitrogen dynamics three years after a severe Araucaria-Nothofagus forest fire. AUSTRAL ECOLOGY. 2012;37(2):153–63.
MLA
Rivas, Y, Dries Huygens, H Knicker, et al. “Soil Nitrogen Dynamics Three Years After a Severe Araucaria-Nothofagus Forest Fire.” AUSTRAL ECOLOGY 37.2 (2012): 153–163. Print.
@article{2120366,
  abstract     = {Wildfires have shaped the biogeography of south Chilean AraucariaNothofagus rainforest vegetation patterns, but their impact on soil properties and associated nutrient cycling remains unclear. Nitrogen (N) availability shows a site-specific response to wildfire events indicating the need for an increased understanding of underlying mechanisms that drive changes in soil N cycling. In this study, we selected unburned and burned sites in a large area of the National Park Tolhuaca that was affected by a stand-replacing wildfire in February 2002. We conducted net N cycling flux measurements (net ammonification, net nitrification and net N mineralization assays) on soils sampled 3 years after fire. In addition, samples were physically fractionated and natural abundance of C and N, and 13C-NMR analyses were performed. Results indicated that standing inorganic N pools were greater in the burned soil, but that no main differences in net N cycling fluxes were observed between unburned and burned sites. In both sites, net ammonification and net nitrification fluxes were low or negative, indicating N immobilization. Multiple linear regression analyses indicated that soil N cycling could largely be explained by two parameters: light fraction (LF) soil organic matter N content and aromatic Chemical Oxidation Resistant Carbon (CORECarom), a relative measure for char. The LF fraction, a strong NH4+ sink, decreased as a result of fire, while CORECarom increased in the burned soil profile and stimulated NO3- production. The absence of increased total net nitrification might relate to a decrease in heterotrophic nitrification after wildfire. We conclude that (i) wildfire induced a shift in N transformation pathways, but not in total net N mineralization, and (ii) stable isotope measurements are a useful tool to assess post-fire soil organic matter dynamics.},
  author       = {Rivas, Y and Huygens, Dries and Knicker, H and Godoy, R and Matus, F and Boeckx, Pascal},
  issn         = {1442-9985},
  journal      = {AUSTRAL ECOLOGY},
  keyword      = {CHEMICAL OXIDATION,STABLE-ISOTOPES,NATURAL-ABUNDANCE,MICROBIAL BIOMASS,PONDEROSA PINE,ORGANIC-MATTER,C-13 NMR-SPECTRA,stable isotope,organic matter fractionation,N cycling,Chile,13C-NMR,Andisol,CONIFER FORESTS,BLACK CARBON,LONG-TERM},
  language     = {eng},
  number       = {2},
  pages        = {153--163},
  title        = {Soil nitrogen dynamics three years after a severe Araucaria-Nothofagus forest fire},
  url          = {http://dx.doi.org/10.1111/j.1442-9993.2011.02258.x},
  volume       = {37},
  year         = {2012},
}

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