Phenolic root exudate and tissue compounds vary widely among temperate forest tree species and have contrasting effects on soil microbial respiration

Marie J. Zwetsloot, André Kessler, Taryn L. Bauerle*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

24 Citations (Scopus)

Abstract

Root–soil interactions fundamentally affect the terrestrial carbon (C) cycle and thereby ecosystem feedbacks to climate change. This study addressed the question of whether the secondary metabolism of different temperate forest tree species can affect soil microbial respiration. We hypothesized that phenolics can both increase and decrease respiration depending on their function as food source, mobilizer of other soil resources, signaling compound, or toxin. We analyzed the phenolic compounds from root exudates and root tissue extracts of six tree species grown in a glasshouse using high-performance liquid chromatography. We then tested the effect of individual phenolic compounds, representing the major identified phenylpropanoid compound classes, on microbial respiration through a 5-d soil incubation. Phenolic root profiles were highly species-specific. Of the eight classes identified, flavonoids were the most abundant, with flavanols being the predominating sub-class. Phenolic effects on microbial respiration ranged from a 26% decrease to a 46% increase, with reduced respiration occurring in the presence of compounds possessing a catechol ring. Tree species variation in root phenolic composition influences the magnitude and direction of root effects on microbial respiration. Our data support the hypothesis that functional group rather than biosynthetic class determines the root phenolic effect on soil C cycling.

Original languageEnglish
Pages (from-to)530-541
Number of pages12
JournalNew Phytologist
Volume218
Issue number2
DOIs
Publication statusPublished - Apr 2018
Externally publishedYes

Keywords

  • phenolics
  • rhizosphere
  • root exudates
  • root priming
  • secondary metabolism
  • temperate forest tree species

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