Soil aggregate size distribution mediates microbial climate change feedbacks

Ming Nie, Elise Pendall, Colin Bell, Matthew D. Wallenstein

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

Soil carbon stabilization is known to depend in part on its distribution in structural aggregates, and upon soil microbial activity within the aggregates. However, the influence of climate change on continued soil C storage within aggregates of different size classes is unknown. In this study, we applied a modified dry-sieving technique to separate bulk soil into three fractions (>1 mm large macroaggregate; 0.25–1 mm small macroaggregate; <0.25 mm microaggregate), and measured the activities of seven microbial enzymes involved in the cycling of C, N, and P, in the context of a long-term elevated CO2 and warming experiment. Significant effects of aggregate size were found for most enzyme activities, enzyme stoichiometry, and specific enzyme activities (per unit of microbial biomass), suggesting that aggregate size distribution mediates microbial feedbacks to climate change. C decomposition enzyme activities, the ratios of total C:N and C:P enzyme activity, and the specific enzyme activity for C decomposition were significantly higher in the microaggregates across climate treatments. However, specific enzyme activity for N decomposition was significantly higher in macroaggregates. Increased specific enzyme activity for C decomposition under both elevated CO2 and warming suggests that these climate changes can enhance microbial ability to decompose soil organic matter (SOM). Moreover, changes in the enzyme C:N:P stoichiometry suggest that soil microorganisms may be able to adjust nutrient acquisition ratios in response to climate change. Our study suggests that identifying and modeling aggregate size as a function of SOM decomposition could improve our mechanistic understanding of soil biogeochemical cycling responses to climate change.

Original languageEnglish
Pages (from-to)357-365
Number of pages9
JournalSoil Biology and Biochemistry
Volume68
Early online date18 Oct 2013
DOIs
Publication statusPublished - Jan 2014

Keywords

  • climate change
  • elevated CO2
  • warming
  • soil aggregate
  • extracellular enzyme activity
  • specific enzyme activity
  • enzyme stoichiometry
  • elevated atmospheric CO2
  • organic-matter dynamics
  • carbon-cycle feedbacks
  • semiarid grassland
  • enzyme-activity
  • forest soils
  • N deposition
  • nitrogen
  • community
  • stoichiometry

Cite this

Soil aggregate size distribution mediates microbial climate change feedbacks. / Nie, Ming; Pendall, Elise; Bell, Colin; Wallenstein, Matthew D.

In: Soil Biology and Biochemistry, Vol. 68, 01.2014, p. 357-365.

Research output: Contribution to journalArticle

Nie, Ming ; Pendall, Elise ; Bell, Colin ; Wallenstein, Matthew D. / Soil aggregate size distribution mediates microbial climate change feedbacks. In: Soil Biology and Biochemistry. 2014 ; Vol. 68. pp. 357-365.
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abstract = "Soil carbon stabilization is known to depend in part on its distribution in structural aggregates, and upon soil microbial activity within the aggregates. However, the influence of climate change on continued soil C storage within aggregates of different size classes is unknown. In this study, we applied a modified dry-sieving technique to separate bulk soil into three fractions (>1 mm large macroaggregate; 0.25–1 mm small macroaggregate; <0.25 mm microaggregate), and measured the activities of seven microbial enzymes involved in the cycling of C, N, and P, in the context of a long-term elevated CO2 and warming experiment. Significant effects of aggregate size were found for most enzyme activities, enzyme stoichiometry, and specific enzyme activities (per unit of microbial biomass), suggesting that aggregate size distribution mediates microbial feedbacks to climate change. C decomposition enzyme activities, the ratios of total C:N and C:P enzyme activity, and the specific enzyme activity for C decomposition were significantly higher in the microaggregates across climate treatments. However, specific enzyme activity for N decomposition was significantly higher in macroaggregates. Increased specific enzyme activity for C decomposition under both elevated CO2 and warming suggests that these climate changes can enhance microbial ability to decompose soil organic matter (SOM). Moreover, changes in the enzyme C:N:P stoichiometry suggest that soil microorganisms may be able to adjust nutrient acquisition ratios in response to climate change. Our study suggests that identifying and modeling aggregate size as a function of SOM decomposition could improve our mechanistic understanding of soil biogeochemical cycling responses to climate change.",
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note = "We thank Prof. Karl Ritz and anonymous referees for their constructive comments on the early version of this manuscript, which greatly improved the quality of our article. We also thank Dan LeCain for overall project management and Jack Morgan for leading the PHACE experiment. This material is based upon work supported by the US Department of Agriculture, US Department of Energy's Office of Science (BER), through the Terrestrial Ecosystem Science program, and by the National Science Foundation (DEB# 1021559). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.",
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AB - Soil carbon stabilization is known to depend in part on its distribution in structural aggregates, and upon soil microbial activity within the aggregates. However, the influence of climate change on continued soil C storage within aggregates of different size classes is unknown. In this study, we applied a modified dry-sieving technique to separate bulk soil into three fractions (>1 mm large macroaggregate; 0.25–1 mm small macroaggregate; <0.25 mm microaggregate), and measured the activities of seven microbial enzymes involved in the cycling of C, N, and P, in the context of a long-term elevated CO2 and warming experiment. Significant effects of aggregate size were found for most enzyme activities, enzyme stoichiometry, and specific enzyme activities (per unit of microbial biomass), suggesting that aggregate size distribution mediates microbial feedbacks to climate change. C decomposition enzyme activities, the ratios of total C:N and C:P enzyme activity, and the specific enzyme activity for C decomposition were significantly higher in the microaggregates across climate treatments. However, specific enzyme activity for N decomposition was significantly higher in macroaggregates. Increased specific enzyme activity for C decomposition under both elevated CO2 and warming suggests that these climate changes can enhance microbial ability to decompose soil organic matter (SOM). Moreover, changes in the enzyme C:N:P stoichiometry suggest that soil microorganisms may be able to adjust nutrient acquisition ratios in response to climate change. Our study suggests that identifying and modeling aggregate size as a function of SOM decomposition could improve our mechanistic understanding of soil biogeochemical cycling responses to climate change.

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KW - forest soils

KW - N deposition

KW - nitrogen

KW - community

KW - stoichiometry

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