Sammanfattning

Enrichment of forest soils with inorganic nitrogen (N) tends to inhibit oxidative enzyme expression by microbes and reduces plant litter and soil organic matter decomposition rates. Without further explanation than is currently presented in the scientific literature, we argue that upregulation of oxidative enzymes seems a more competitive response to prolonged N enrichment at high rates than the observed downregulation. Thus, as it stands, observed responses are inconsistent with predicted responses. In this article, we present a hypothesis that resolves this conflict. We suggest that high rates of N addition alter the competitive balance between enzymatic lignin mineralisation and non-enzymatic lignin oxidation. Using metatransciptomics and chemical assays to examine boreal forest soils, we found that N addition suppressed peroxidase activity, but not iron reduction activity (involved in non-enzymatic lignin oxidation). Our hypothesis seems positioned as a parsimonious and empirically consistent working model that warrants further testing.

Nyckelord

Lignin decomposition; Soil carbon cycling; Nitrogen fertilisation; Brown and white rot fungi; Oxidative enzymes; Fenton reaction

Publicerad i

Soil Biology and Biochemistry
2019, Volym: 137, artikelnummer: 107570
Utgivare: PERGAMON-ELSEVIER SCIENCE LTD

SLU författare

• Bonner, Mark

  • Institutionen för skogens ekologi och skötsel, Sveriges lantbruksuniversitet
    

• Castro, David

  • Institutionen för skoglig genetik och växtfysiologi, Sveriges lantbruksuniversitet
    

• Sundström, Görel

  • Institutionen för skoglig genetik och växtfysiologi, Sveriges lantbruksuniversitet
    

• Hurry, Vaughan

  • Institutionen för skoglig genetik och växtfysiologi, Sveriges lantbruksuniversitet
    

• Näsholm, Torgny

  • Institutionen för skogens ekologi och skötsel, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Markvetenskap
Skogsvetenskap


Publikationens identifierare

DOI: https://doi.org/10.1016/j.soilbio.2019.107570

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/102276