The Effect of Resource Islands on Abundance and Diversity of Bacteria in Arid Soils |
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Authors: | Ami?Bachar M?Ines?M?Soares Email author" target="_blank">Osnat?GillorEmail author |
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Institution: | (1) Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, 84990 Beersheba, Israel |
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Abstract: | Bacteria and nutrients were determined in upper soil samples collected underneath and between canopies of the dominant perennial
in each of three sites along a steep precipitation gradient ranging from the Negev desert in the south of Israel to a Mediterranean
forest in the north. Bacterial abundance, monitored by phospholipid fatty acid analysis, was significantly higher under the
shrub canopy (compared to barren soils) in the arid and semi-arid sites but not in the Mediterranean soils. Bacterial community
composition, determined using terminal restriction fragment length polymorphism and clone libraries, differed according to
the sample’s origin. Closer examination revealed that in the arid and semi-arid sites, α-Proteobacteria are more abundant
under the shrub canopy, while barren soils are characterized by a higher abundance of Actinobacteria. The bacterial communities
in the Mediterranean soils were similar in both patch types. These results correspond to the hypothesis of “resource islands”,
suggesting that shrub canopies provide a resource haven in low-resource landscapes. Yet, a survey of the physicochemical parameters
of inter- and under-shrub soils could not attribute the changes in bacterial diversity to soil moisture, organic matter, or
essential macronutrients. We suggest that in the nutrient-poor soils of the arid and semi-arid sites, bacteria occupying the
soil under the shrub canopy may have longer growth periods under favorable conditions, resulting in their increased biomass
and altered community composition. |
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