, Volume 76, Issue 3, pp 517-537

First online:

Spatial Heterogeneity and Soil Nitrogen Dynamics in a Burned Black Spruce Forest Stand: Distinct Controls at Different Scales

  • Erica A. H. SmithwickAffiliated withDepartment of Zoology, University of Wisconsin Email author 
  • , Michelle C. MackAffiliated withDepartment of Botany, University of Florida
  • , Monica G. TurnerAffiliated withDepartment of Zoology, University of Wisconsin
  • , F. Stuart ChapinIIIAffiliated withInstitute of Arctic Biology, University of Alaska
  • , Jun ZhuAffiliated withDepartment of Statistics, University of WisconsinDepartment of Soil Science, University of Wisconsin
  • , Teri C. BalserAffiliated withDepartment of Soil Science, University of Wisconsin

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We evaluated spatial patterns of soil N and C mineralization, microbial community composition (phospholipid fatty acids), and local site characteristics (plant/forest floor cover, soil pH, soil %C and %N) in a 0.25-ha burned black spruce forest stand in interior Alaska. Results indicated that factors governing soil N and C mineralization varied at two different scales. In situ net N mineralization was autocorrelated with microbial community composition at relatively broad scales (∼ ∼8 m) and with local site characteristics (`site' axis 1 of non-metric scaling ordination) at relatively fine scales (2–4 m). At the scale of the individual core, soil moisture was the best predictor of in situ net N mineralization and laboratory C mineralization, explaining between 47 and 67% of the variation (p < 0.001). Ordination of microbial lipid data showed that bacteria were more common in severely burned microsites, whereas fungi were more common in low fire severity microsites. We conclude that C and N mineralization rates in this burned black spruce stand were related to different variables depending on the scale of analysis, suggesting the importance of considering multiple scales of variability among key drivers of C and N transformations.


Alaska Fire Microbial community composition Mineralization Nitrogen Spatial heterogeneity