Earthworms modify plant biomass and nitrogen capture under conditions of soil nutrient heterogeneity and elevated atmospheric CO<inf>2</inf> concentrations
Abstract
Earthworms modify the way roots respond to soil nutrient patchiness. However, few
studies have evaluated the joint effects of earthworms and soil heterogeneity on plant
community biomass and species dominance, and none of them have assessed the influence
of different patch features and environmental conditions on such effects. We evaluated
how soil nutrient heterogeneity, earthworms (Eisenia fetida), organic material quality
(15N-labelled leaves and roots of contrasting C: N ratios) and elevated atmospheric
CO2 concentrations (phytotron chambers) affected the resource-use strategy, biomass
and species dominance of mixtures formed by Lolium perenne L. and Plantago lanceolata
L. Soil heterogeneity decreased N capture from the organic material, especially in
the presence of earthworms. Mixtures experienced a 26 and 36% decrease in shoot and
root biomass when earthworms were added to the heterogeneous microcosms, but only
with high quality organic material. The dominance of L. perenne was lower under conditions
of elevated CO2, nutrient heterogeneity and earthworms. Our data suggest that earthworms
can neutralize positive plant growth responses to soil heterogeneity by exacerbating
decreases in the supply of N to the plant. Specifically, earthworms foraging for high
quality patches may stimulate microbial N immobilization, translating into lower N
capture by plants. Increases in casting activity under elevated CO2, and hence in
microbial N immobilization, may also explain why earthworms modulated the effects
of soil heterogeneity and CO2 concentrations on plant community structure. We show
that earthworms, absent from most soil nutrient heterogeneity studies, mediate plant
biomass responses to nutrient patchiness by affecting N capture. Future plant-foraging
behaviour studies should consider the roles played by soil engineers such as earthworms,
so that results can be better extrapolated to natural communities. © 2014 Elsevier
Ltd.
Type
Journal articleSubject
Science & TechnologyLife Sciences & Biomedicine
Soil Science
Agriculture
Aboveground-belowground interactions
Earthworms
N-15 plant material
Plant biomass
Plant resource use strategy
Resource quality
LITTER DECOMPOSITION
GRASSLAND
RESPONSES
GROWTH
FAUNA
MICROORGANISMS
AVAILABILITY
POPULATIONS
PERFORMANCE
COMPETITION
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https://hdl.handle.net/10161/24230Published Version (Please cite this version)
10.1016/j.soilbio.2014.08.002Publication Info
García-Palacios, Pablo; Maestre, Fernando T; Bradford, Mark A; & Reynolds, James F (2014). Earthworms modify plant biomass and nitrogen capture under conditions of soil nutrient
heterogeneity and elevated atmospheric CO<inf>2</inf> concentrations. Soil Biology and Biochemistry, 78. pp. 182-188. 10.1016/j.soilbio.2014.08.002. Retrieved from https://hdl.handle.net/10161/24230.This is constructed from limited available data and may be imprecise. To cite this
article, please review & use the official citation provided by the journal.
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Show full item recordScholars@Duke
James F. Reynolds
Professor Emeritus
Integrated assessment of complex human-environmental systems; Land degradation and
desertification in global drylands; Conceptual frameworks and models to advance the
science of dryland development

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