Mycorrhizal associations of trees have different indirect effects on organic matter decomposition

  • Authors: Taylor, Melanie K.; Lankau, Richard A.; Wurzburger, Nina; de Vries, Franciska
  • Publication Year: 2016
  • Publication Series: Scientific Journal (JRNL)
  • Source: Journal of Ecology
  • DOI: 10.1111/1365-2745.12629

Abstract

1. Organic matter decomposition is the main process by which carbon (C) is lost from terrestrial
ecosystems, and mycorrhizal associations of plants (i.e. arbuscular mycorrhizas (AM) and ectomycorrhizas
(ECM)) may have different indirect effects on this loss pathway. AM and ECM plants differ
in the soil decomposers they promote and the quality of litter they produce, which may result in
different patterns of organic matter decomposition, and hence, soil C loss.
2. To determine how mycorrhizal associations indirectly affect decomposer activity, we collected
soils and litters from four AM and four ECM tree species from a mixed-deciduous temperate forest
for a field and laboratory study. We first characterized in situ patterns in soil chemistry and soil
microbial biomass among these eight tree species. We then conducted a microcosm experiment with
mineral soils, leaf litter and fine roots originating from these tree species, where we reciprocally
crossed litters and soils, and quantified the rate of heterotrophic respiration over a 140-day laboratory
incubation.
3. In natural forest conditions, AM tree soils contained lower total C and microbial biomass C:N
relative to ECM tree soils. In our microcosm experiment, AM soils supported greater heterotrophic
respiration than did ECM soils. The addition of AM litter stimulated respiration more than did ECM
litter, owing to the lower C:N of AM litter. Matching the mycorrhizal identity of litter and soil
resulted in a difference in total respiration, such that combinations of AM litters with AM soils lost
more C than did combinations of ECM litters with ECM soils.
4. Synthesis. Our findings demonstrate that AM and ECM trees have differing indirect effects on
soil decomposer activity through the decomposers they cultivate and/or the quality of organic matter
they produce. Mycorrhizal differences in litter quality accentuate these effects on soil C loss and
may explain patterns in soil C dynamics in terrestrial ecosystems

  • Citation: Taylor, Melanie K.; Lankau, Richard A.; Wurzburger, Nina; de Vries, Franciska 2016. Mycorrhizal associations of trees have different indirect effects on organic matter decomposition. Journal of Ecology. 9p.  10.1111/1365-2745.12629
  • Keywords: arbuscular mycorrhizas, biogeochemistry, carbon, decomposition, ectomycorrhizas, nitrogen, plant–soil relationship, soil organic matter
  • Posted Date: September 15, 2016
  • Modified Date: September 19, 2016
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