Microbial and Denitrifying Bacterial Community Under Pine and Eucalypt Plantations at Extreme Ends of a Groundwater Depth Gradient.

Microbes play a critical role in mediating soil organic matter decomposition and nutrient cycling in terrestrial ecosystems.  Both biotic factors, such as plant species, and abiotic factors, such as soil physical and chemical properties, affect the diversity and function of the soil microbial community.  A clear understanding on how biotic and abiotic factors influence the microbial community and its functional role in terrestrial ecosystems is fundamental to terrestrial biogeochemistry. Soil bacterial and fungal communities, and denitrifying bacteria were studied under paired loblolly pine (Pinus taeda) and eucalypt (Eucalyptus benthamii) forest plantations. Three paired plots were located in deep groundwater (>10m) and thee paired plots were located in shallow groundwater (<2m).  Length Heterogeneity PCR (LH-PCR) and fragment analysis based on bacterial 16S rRNA gene and fungal ITS-1 were performed for soil microbial diversity and community analyses.  The denitrifying bacterial nirK gene was detected using quantitative PCR (QPCR) and Denaturing Gradient Gel Electrophoresis (DGGE). Soil fungal community structure differed between the forest plantation types (ANOSIM p = 0.036), but was not influenced by depth to groundwater (ANOSIM p = 0.343). Conversely, soil bacterial community structure remained similar between the forest plantation types (ANOSIM p = 0.183), but differed between groundwater depths (ANOSIM p = 0.048). There was no difference of overall denitrifying bacterial community detected by nirK gene either between different forest plantation types or groundwater depths, although unique nirK genes were observed for each forest plantation. The different microbial community observed within two forest plantations and at shallow and deep groundwater depths may provide important information for the intensity of management and planting a woody crop eucalypt species with even higher production potential than loblolly pine.     [DPA1] 

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 [DPA1]I think we need to still work on the conclusion here.

See more from this Division: SSSA Division: Soil Biology & Biochemistry
See more from this Session: Soil Biology & Biochemistry: II

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