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The link between nitrogen cycling an...

Boyle, Stephanie A.

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The link between nitrogen cycling and soil microbial community composition in forest soils of Western Oregon.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The link between nitrogen cycling and soil microbial community composition in forest soils of Western Oregon./
Author:	Boyle, Stephanie A.
Description:	142 p.
Notes:	Adviser: David D. Myrold.
Contained By:	Dissertation Abstracts International68-02B.
Subject:	Agriculture, Soil Science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3253156

The link between nitrogen cycling and soil microbial community composition in forest soils of Western Oregon.
Boyle, Stephanie A.

The link between nitrogen cycling and soil microbial community composition in forest soils of Western Oregon. - 142 p.

Adviser: David D. Myrold.

Thesis (Ph.D.)--Oregon State University, 2007.

The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations in forest soils. The first study consisted of a reciprocal transfer experiment where soil cores were transferred between high-elevation forest and adjacent meadow environments. It focused on bacterial denitrifying communities by measuring denitrification enzyme activity and community composition as determined by terminal restriction fragment length polymorphism (T-RFLP) profiles targeting the gene for nitrous oxide reductase (nosZ). Results from this experiment showed that while transferring meadow soils into forests increased denitrification rate, denitrifying community composition did not appear to change after two years. The second study examined N cycling and microbial community composition in soils from 20-year-old experimental tree plantations with pure stands of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in a high- and a low-productivity forest. 15N isotope dilution was combined with antibiotics to assess the roles of bacteria and fungi in N mineralization and nitrification. Data showed that nitrification was a major sink for NH4+ in all soil types and bacteria were the primary nitrifiers. Increased ammonification following antibiotic additions suggested that organic N may be important for the growth of heterotrophic bacteria and fungi. Results of nitrification potential assays showed that most nitrification was acetylene insensitive (autotrophic). Community composition of ammonia-oxidizing bacteria and archaea were assessed by targeting bacterial and archaeal ammonia-monooxygenase (amoA) genes. The composition and population size of ammonia-oxidizing bacteria differed between Douglas fir and red alder and tended to group with Nitrosospira clusters 2 and 4. Archaeal amoA was only amplified from the high-productivity site and grouped with other archaeal clones from soil and estuary sediments. Environmental factors affected rates of N cycling within two years, but community compositional changes responded more slowly, e.g., nitrifying communities differed between 20-year-old tree stands. This suggests that if environmental changes persist they may lead to changes in microbial community composition.Subjects--Topical Terms:

1017824
Agriculture, Soil Science.

The link between nitrogen cycling and soil microbial community composition in forest soils of Western Oregon.
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035 $a (UMI)AAI3253156
035 $a AAI3253156
040 $a UMI $c UMI
100 1 $a Boyle, Stephanie A. $3 1263311
245 1 4 $a The link between nitrogen cycling and soil microbial community composition in forest soils of Western Oregon.
300 $a 142 p.
500 $a Adviser: David D. Myrold.
500 $a Source: Dissertation Abstracts International, Volume: 68-02, Section: B, page: 0689.
502 $a Thesis (Ph.D.)--Oregon State University, 2007.
520 $a The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations in forest soils. The first study consisted of a reciprocal transfer experiment where soil cores were transferred between high-elevation forest and adjacent meadow environments. It focused on bacterial denitrifying communities by measuring denitrification enzyme activity and community composition as determined by terminal restriction fragment length polymorphism (T-RFLP) profiles targeting the gene for nitrous oxide reductase (nosZ). Results from this experiment showed that while transferring meadow soils into forests increased denitrification rate, denitrifying community composition did not appear to change after two years. The second study examined N cycling and microbial community composition in soils from 20-year-old experimental tree plantations with pure stands of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in a high- and a low-productivity forest. 15N isotope dilution was combined with antibiotics to assess the roles of bacteria and fungi in N mineralization and nitrification. Data showed that nitrification was a major sink for NH4+ in all soil types and bacteria were the primary nitrifiers. Increased ammonification following antibiotic additions suggested that organic N may be important for the growth of heterotrophic bacteria and fungi. Results of nitrification potential assays showed that most nitrification was acetylene insensitive (autotrophic). Community composition of ammonia-oxidizing bacteria and archaea were assessed by targeting bacterial and archaeal ammonia-monooxygenase (amoA) genes. The composition and population size of ammonia-oxidizing bacteria differed between Douglas fir and red alder and tended to group with Nitrosospira clusters 2 and 4. Archaeal amoA was only amplified from the high-productivity site and grouped with other archaeal clones from soil and estuary sediments. Environmental factors affected rates of N cycling within two years, but community compositional changes responded more slowly, e.g., nitrifying communities differed between 20-year-old tree stands. This suggests that if environmental changes persist they may lead to changes in microbial community composition.
590 $a School code: 0172.
650 4 $a Agriculture, Soil Science. $3 1017824
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Biology, Microbiology. $3 1017734
690 $a 0329
690 $a 0410
690 $a 0481
710 2 $a Oregon State University. $3 625720
773 0 $t Dissertation Abstracts International $g 68-02B.
790 $a 0172
790 1 0 $a Myrold, David D., $e advisor
791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3253156