Polkadot JAM Slides - Token2049 - By Dr. Gavin Wood
Plant patchiness effect on microbial community
1. Title: Effect of plant patchiness on soil microbial
community structure
Authors: A. Nejidat, E. Ben-David, Y. Sher, R. Golden, E. Zaady and Z. Ronen
Department of Environmental Hydrology and Microbiology, Zukerberg Institute for
Water Research, Blaunstein Institutes for Desert Research, Ben-Gurion University of
the Negev, Sede Boqer
Drylands, Deserts and Desertification-14.12.2008, Sede Boqer
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2. Aim: to examine the effect of plant and plant type on bulk soil
microbial community structure and activity in patchy desert
landscape
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3. Research locations
Long Term Ecological Research Sites
Sayeret Shaked
• Northern Negev
• Semiarid grassland
• Long term average rainfall - 200 mm
Avdat
• Central Negev
• Arid land
• Long term average rainfall - 90 mm
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6. Methods
- Phospholipids fatty acid (PLFA) analysis (major
microbial groups)
- Denaturing gradient gel electrophoresis (DGGE)
of phylogenetic DNA markers (species diversity)
and Real Time PCR for gene copy quantification
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8. Results
Selected soil chemical parameters in Avdat and Shaked sampling sites.
Samples pH EC RWC OM TAN NO2--N NO3--N
μScm-1 (%) (%) mg/kg
mg/kg mg/kg
Zd 8.03 2130 7.05 2.38 9.67 0.97 46.17
Hs 8.40 1958 4.98 2.60 7.47 0.19 51.04
ISPA 8.41 748 5.28 1.68 6.50 0.01 25.68
Nm 8.27 287 4.33 2..28 6.14 0.05 21.31
Th 8.11 232 5.23 2.30 6.97 0.24 22.04
ISPS 8.39 174 4.35 1.07 4.79 0.01 18.60
ANOVA Statistics
Avdat vs. Shaked ns <0.001 ns ns <0.05 ns <0.01
SUCA vs. SUCB ns <0.001 ns ns <0.1 ns <0.01
SUCA vs. BSCA ns <0.1 ns <0.1 ns ns <0.05
SUCS vs. BSCS <0.05 <0.005 ns <0.01 <0.05 ns Ns
BSCA vs. BSCS ns <0.1 ns <0.1 <0.05 ns <0.01
Zd vs. Hs, BSCA <0.05 - - - - - -
Average values and standard deviation are indicated (n=3). Significant difference between groups of
replicates/samples was tested using one-way ANOVA followed by Tukey’s multiple comparison test; p value is
indicated; ns, not significant. SUCA, soil under canopy from Avdat; SUCB, soil under canopy from Shaked; BSCA,
biological soil crust from Avdat; BSCB, biological soil crust from Shaked.
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9. (a) (b)
(a) PCA ordination of the PLFA relative abundance data (mol %) for all of Avdat
sampling sites
(b) PCA ordination of the PLFA relative abundance data (mol %) for all of
Shaked sampling sites
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10. a b
(a) Redundancy ordination (RDA) triplot of sites, PLFA relative abundance (mol %)
and soil quality variables for all of Avdat sampling sites (based on first two axes).
(b) RDA triplot of sites, PLFA relative abundance (mol %) and soil quality variables
for10 of Shaked sampling sites (based on first two axes)
all
11. RDA triplot of sites, PLFA relative abundance (mol %) and soil quality variables for
all of Shaked and Avdat ISP replicates.
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12. Summary: Part I
Based on the PCA of the PLFA profile and PLFA biomarkers with structural
group interpretation the results suggest:
• A shift in soil microbial community structure from underneath plants
compared with soils between plants.
• Plant primarily influences the character of surrounding microbial
community and plant type may produce a secondary influence.
• Location (Avdat vs Shaked) have significant effect on the microbial
community in the intershrub spaces; possibly through climatic differences
or indirect effect of plant types
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13. • Dominance of Gram-negative populations
• Higher proportions of Gram-positive populations in SUC samples compared
with ISP samples
• Higher proportions of fungi, cyanobacteria and anaerobes in ISP samples
compared with SUC samples
• RDAs suggest that nitrate was a major determinant segregating the PLFA
profiles of the intershrub spaces from the SUC.
• Nitrate is also a major factor together with organic matter in segregating the
intershrub spaces of Avdat and Shaked
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19. Numbers vs Activity
500
Ammonia Oxidation Potential
y = 86.028x + 250.71
R2 = 0.5302
390
μg-N/Kg/h
280
170
0 0.5 1 1.5 2 2.5
% Bacterial amoA copies
of total amoA copies
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20. Conclusions
• Plant presence and plant type affect soil
microbial community structure and activity.
• The impact on nutrients transformations
may affect soil fertility.
• It is suggested to consider these aspects
when introducing plants for combating
desertification
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