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The microbial community size, structure, and process rates along natural gradients of soil salinity

Rath, Kristin M. LU ; Murphy, Daniel N. and Rousk, Johannes LU (2019) In Soil Biology and Biochemistry 138.
Abstract

Over 840 M ha of arable land is affected by salinization, and the area is predicted to increase due to global change. Assessments of the status of the microbial community in saline soils have frequently been based on microbial biomass estimates, which might not accurately reflect microbial process rates in soil. Moreover, assessments of how the relative importance of major decomposer groups bacteria and fungi are affected by salinity remain inconclusive. In this study we set out to assess the soil microbial community size, structure and process rates along two salinity gradients. To distinguish between the direct effects of high salinity and indirect effects resulting from reduced soil organic matter (OM) concentrations in saline soils... (More)

Over 840 M ha of arable land is affected by salinization, and the area is predicted to increase due to global change. Assessments of the status of the microbial community in saline soils have frequently been based on microbial biomass estimates, which might not accurately reflect microbial process rates in soil. Moreover, assessments of how the relative importance of major decomposer groups bacteria and fungi are affected by salinity remain inconclusive. In this study we set out to assess the soil microbial community size, structure and process rates along two salinity gradients. To distinguish between the direct effects of high salinity and indirect effects resulting from reduced soil organic matter (OM) concentrations in saline soils we also assessed the gradients following plant litter amendments to compensate for differences in OM content between soils and isolate the effect of salinity. The research aims were to (i) investigate the microbial biomass responses to salinity as estimated based on both PLFA concentrations and qPCR measurements and to compare these responses to those of respiration and microbial growth, (ii) compare the responses of bacteria and fungi to increased salinity and (iii) assess the responses of these microbial variables to the alleviation of OM scarcity expected in saline soils. Microbial biomass estimates generally were less negatively affected by salinity than bacterial growth and respiration, and were not correlated to rates of microbial growth or respiration rates. While bacterial growth was strongly inhibited by salinity, fungal growth was similar in soils of all salinities, indicating a higher fungal tolerance to salinity. OM additions increased process rates in saline soils and alleviated some of the negative impact of salinity on respiration and growth. In conclusion, this study demonstrates differential responses of saprotrophic fungi and bacteria to increasing salinity and that bacteria are directly impacted by soil salinity while fungi are responding to the indirect effect by salinity related to reduced plant C input.

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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
Agricultural contaminants, Australasia, Dormant, Potentially active or active biomass, Salinization, Sodic and arid drylands, Soil remediation
in
Soil Biology and Biochemistry
volume
138
article number
107607
publisher
Elsevier
external identifiers
  • scopus:85072644389
ISSN
0038-0717
DOI
10.1016/j.soilbio.2019.107607
language
English
LU publication?
yes
id
e42e5dcc-609f-4dc1-a010-c605d5dde031
date added to LUP
2019-10-02 14:08:22
date last changed
2020-01-13 02:26:27
@article{e42e5dcc-609f-4dc1-a010-c605d5dde031,
  abstract     = {<p>Over 840 M ha of arable land is affected by salinization, and the area is predicted to increase due to global change. Assessments of the status of the microbial community in saline soils have frequently been based on microbial biomass estimates, which might not accurately reflect microbial process rates in soil. Moreover, assessments of how the relative importance of major decomposer groups bacteria and fungi are affected by salinity remain inconclusive. In this study we set out to assess the soil microbial community size, structure and process rates along two salinity gradients. To distinguish between the direct effects of high salinity and indirect effects resulting from reduced soil organic matter (OM) concentrations in saline soils we also assessed the gradients following plant litter amendments to compensate for differences in OM content between soils and isolate the effect of salinity. The research aims were to (i) investigate the microbial biomass responses to salinity as estimated based on both PLFA concentrations and qPCR measurements and to compare these responses to those of respiration and microbial growth, (ii) compare the responses of bacteria and fungi to increased salinity and (iii) assess the responses of these microbial variables to the alleviation of OM scarcity expected in saline soils. Microbial biomass estimates generally were less negatively affected by salinity than bacterial growth and respiration, and were not correlated to rates of microbial growth or respiration rates. While bacterial growth was strongly inhibited by salinity, fungal growth was similar in soils of all salinities, indicating a higher fungal tolerance to salinity. OM additions increased process rates in saline soils and alleviated some of the negative impact of salinity on respiration and growth. In conclusion, this study demonstrates differential responses of saprotrophic fungi and bacteria to increasing salinity and that bacteria are directly impacted by soil salinity while fungi are responding to the indirect effect by salinity related to reduced plant C input.</p>},
  author       = {Rath, Kristin M. and Murphy, Daniel N. and Rousk, Johannes},
  issn         = {0038-0717},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Soil Biology and Biochemistry},
  title        = {The microbial community size, structure, and process rates along natural gradients of soil salinity},
  url          = {http://dx.doi.org/10.1016/j.soilbio.2019.107607},
  doi          = {10.1016/j.soilbio.2019.107607},
  volume       = {138},
  year         = {2019},
}