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Microbial community response to hydration-desiccation cycles in desert soil

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ABSTRACT

Life in desert soil is marked by episodic pulses of water and nutrients followed by long periods of drought. While the desert flora and fauna flourish after rainfall the response of soil microorganisms remains unclear and understudied. We provide the first systematic study of the role of soil aqueous habitat dynamics in shaping microbial community composition and diversity. Detailed monitoring of natural microbial communities after a rainfall event revealed a remarkable decrease in diversity and a significant transition in community composition that were gradually restored to pre-rainfall values during soil desiccation. Modelling results suggest a critical role for the fragmented aqueous habitat in maintaining microbial diversity under dry soil conditions and diversity loss with wetting events that increase connectivity among habitats. This interdisciplinary study provides new insights into wetting and drying processes that promote and restore the unparalleled microbial diversity found in soil.

No MeSH data available.


Richness and evenness of soil bacterial populations sampled in three adjacent plots during a wetting-drying cycle.Population richness was expressed as the number of observed species (A) and population evenness is displayed using Pielou’s evenness index (or Shannon’s evenness) (B). The trend line is the averaged value of the data. The measured gravimetric water content of each plot (in corresponding colours) and the averaged values are given in (C).
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f2: Richness and evenness of soil bacterial populations sampled in three adjacent plots during a wetting-drying cycle.Population richness was expressed as the number of observed species (A) and population evenness is displayed using Pielou’s evenness index (or Shannon’s evenness) (B). The trend line is the averaged value of the data. The measured gravimetric water content of each plot (in corresponding colours) and the averaged values are given in (C).

Mentions: The variations in relative abundance were translated to changes in soil microbial diversity. Figure 2 depicts the dynamics of field measured microbial diversity during the wetting-drying event in terms of richness, observed OTU, and evenness, Pielous’s evenness. In Fig. 2A, the richness index indicated a statistically significant drop during the rain event (days 1 and 2) and initial stages of desiccation (days 4 and 6) (per group t < −11.80, per group p < 1.8 × 10−10, Figure S5, Figure S6, SI Text 2). Similarly, we observed a slight decrease in evenness, but unlike changes in richness, the evenness index displayed gradual but statistically significant changes (field observation F = 77.8, p = 3.015 × 10−6, Figure S5, Figure S6, SI Text 2) and steady recovery during the hydration cycle (Fig. 2B). In the field, we monitored three adjacent plots concomitantly; minute differences in their desiccation rates instigated observable differences in the community (Fig. 2C). For example, the soil in plot 3 (marked as yellow in the figure) dried relatively faster than in plots 1 and 2, possibly leading to earlier onset of changes in microbial diversity in the plot.


Microbial community response to hydration-desiccation cycles in desert soil
Richness and evenness of soil bacterial populations sampled in three adjacent plots during a wetting-drying cycle.Population richness was expressed as the number of observed species (A) and population evenness is displayed using Pielou’s evenness index (or Shannon’s evenness) (B). The trend line is the averaged value of the data. The measured gravimetric water content of each plot (in corresponding colours) and the averaged values are given in (C).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382909&req=5

f2: Richness and evenness of soil bacterial populations sampled in three adjacent plots during a wetting-drying cycle.Population richness was expressed as the number of observed species (A) and population evenness is displayed using Pielou’s evenness index (or Shannon’s evenness) (B). The trend line is the averaged value of the data. The measured gravimetric water content of each plot (in corresponding colours) and the averaged values are given in (C).
Mentions: The variations in relative abundance were translated to changes in soil microbial diversity. Figure 2 depicts the dynamics of field measured microbial diversity during the wetting-drying event in terms of richness, observed OTU, and evenness, Pielous’s evenness. In Fig. 2A, the richness index indicated a statistically significant drop during the rain event (days 1 and 2) and initial stages of desiccation (days 4 and 6) (per group t < −11.80, per group p < 1.8 × 10−10, Figure S5, Figure S6, SI Text 2). Similarly, we observed a slight decrease in evenness, but unlike changes in richness, the evenness index displayed gradual but statistically significant changes (field observation F = 77.8, p = 3.015 × 10−6, Figure S5, Figure S6, SI Text 2) and steady recovery during the hydration cycle (Fig. 2B). In the field, we monitored three adjacent plots concomitantly; minute differences in their desiccation rates instigated observable differences in the community (Fig. 2C). For example, the soil in plot 3 (marked as yellow in the figure) dried relatively faster than in plots 1 and 2, possibly leading to earlier onset of changes in microbial diversity in the plot.

View Article: PubMed Central - PubMed

ABSTRACT

Life in desert soil is marked by episodic pulses of water and nutrients followed by long periods of drought. While the desert flora and fauna flourish after rainfall the response of soil microorganisms remains unclear and understudied. We provide the first systematic study of the role of soil aqueous habitat dynamics in shaping microbial community composition and diversity. Detailed monitoring of natural microbial communities after a rainfall event revealed a remarkable decrease in diversity and a significant transition in community composition that were gradually restored to pre-rainfall values during soil desiccation. Modelling results suggest a critical role for the fragmented aqueous habitat in maintaining microbial diversity under dry soil conditions and diversity loss with wetting events that increase connectivity among habitats. This interdisciplinary study provides new insights into wetting and drying processes that promote and restore the unparalleled microbial diversity found in soil.

No MeSH data available.