Impacts of litter decay on organic leachate composition and reactivity

Research output: Contribution to journalArticle

Abstract

Litter decomposition produces labile and recalcitrant forms of dissolved organic matter (DOM) that significantly affect soil carbon (C) sequestration. Chemical analysis of this DOM can provide important knowledge for understanding soil DOM dynamics, but detailed molecular analyses on litter derived DOM are scarce. Here we use ultrahigh resolution mass spectrometry (FT-ICR MS) to characterize the molecular composition of DOM from fresh and progressively decomposed litter samples. We compared high reactive (HR) and low reactive (LR) litter sources with regard to changes in the chemistry and bioavailability of leachates throughout the early phase of litter decay. We show that litter reactivity is a driver of chemical changes in the leached DOM of litter species. Birch, alder and Vaccinium (i.e. HR) litter initially produced more DOM with a higher lability than that of spruce, pine and wood (i.e. LR) litter. Labile oxidized phenolic compounds were abundant in leachates produced during the initial HR litter decay stages, indicating litter lignin degradation. However, the similarity in chemistry between HR and LR leachates increased during the litter decay process as highly leachable structures in HR litter were depleted. In contrast, chemistry of leachates from LR litter changed little during the litter decay process. The oxygenated phenolic compounds from HR litter were driving the lability of HR leachates and the changes in relative abundance of molecules during DOM incubation. This appeared to result in the creation of stable aliphatic secondary microbial compounds. In LR leachates, lability was driven by labile aliphatic compounds, while more resistant phenolic compounds were associated with recalcitrance. These results show how DOM dynamics follow different paths depending on litter reactivity, which has important implications for soil biogeochemistry and C sequestration.

Details

Authors
Organisations
External organisations
  • Helmholtz Centre for Environmental Research (UFZ)
  • University of Quebec at Trois-Rivières
  • Swedish University of Agricultural Sciences, Umeå
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Soil Science

Keywords

  • Boreal, Decomposition, Dissolved organic matter, DOC, DOM, FT-ICR MS, Litter leaching, Reactivity
Original languageEnglish
Pages (from-to)99-117
Number of pages19
JournalBiogeochemistry
Volume154
Issue number1
Publication statusPublished - 2021 May 1
Publication categoryResearch
Peer-reviewedYes