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Bacterial Communities Under Soil Disturbance : = From Experimental Mixing in the Lab to Tillage and Bioturbation in the Field.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Bacterial Communities Under Soil Disturbance :/
其他題名:	From Experimental Mixing in the Lab to Tillage and Bioturbation in the Field.
作者:	West, Jaimie R.
面頁冊數:	1 online resource (257 pages)
附註:	Source: Dissertations Abstracts International, Volume: 84-12, Section: B.
Contained By:	Dissertations Abstracts International84-12B.
標題:	Soil sciences. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30529068click for full text (PQDT)
ISBN:	9798379723279

Bacterial Communities Under Soil Disturbance : = From Experimental Mixing in the Lab to Tillage and Bioturbation in the Field.
West, Jaimie R.

Bacterial Communities Under Soil Disturbance :From Experimental Mixing in the Lab to Tillage and Bioturbation in the Field. - 1 online resource (257 pages)

Source: Dissertations Abstracts International, Volume: 84-12, Section: B.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2023.

Includes bibliographical references

Soil microhabitats are heterogeneous, disconnected, and isolated. Thus, soil supports a vast diversity of microbial inhabitants. How do physical disturbances-which disrupt soil microhabitats-affect bacterial community composition and community assembly processes (e.g., selection and dispersal)? Starting in the lab, we evaluated how bacterial communities are affected by soil mixing at various frequencies over a 16-week incubation. We hypothesized that soil mixing would decrease bacterial richness, and that community assembly would be driven by homogenizing dispersal and homogeneous selection. Using 16S rRNA gene sequencing, we found support for our hypotheses, and results further implied that the vast diversity observed in soil is a direct function of the generally unmixed, isolated nature of microbial communities. When we recapitulated this soil mixing experiment under anoxic conditions, findings corroborated the original study: soil mixing homogenized bacterial communities and increased fast growth potential, regardless of oxygen regime. Further, we found that the static anoxic environment decreased bacterial richness overall, and suppressed the influence of mixing-driven selection relative to the oxic treatment.We then took these fundamental ecological findings at the laboratory-scale, and applied them to field settings in southern Wisconsin under real-world soil mixing mechanisms, evaluating long-term tillage in agricultural soils and earthworm bioturbation in forested soils. With these field experiments, we specifically targeted the effects of disturbance on soil aggregation-which protects soil organic matter and promotes soil carbon persistence-and the bacterial communities that inhabit soil microaggregates. The effects of tillage mirrored those of the lab mixing experiments, resulting in more homogeneous soil bacterial communities, driven by homogenizing dispersal. However, bioturbation and aggregate generation due to the casting activity of non-native earthworms (co-occurring Amynthas tokioensis and A. agrestis) did not consistently impose a strong selective filter on the soil bacterial community. Despite high levels of activity in an otherwise relatively undisturbed forest environment, it does not seem that this earthworm activity necessarily acts to homogenize soil communities via dispersal. Further, we did not identify major distinctions between bacterial communities of the free microaggregate vs. occluded-within-macroaggregate microaggregate fractions in either the agricultural tillage study or the forest earthworm bioturbation study, thus suggesting that soil microaggregates readily shift between these operationally defined fractions, particularly at the end of the agricultural growing season, or in the presence of Amynthas spp. earthworms. With this work, we improve our understanding of the microbial response to soil disturbance, and thus the potential implications of increased soil disturbance under global change.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798379723279Subjects--Topical Terms:

2122699
Soil sciences.
Subjects--Index Terms:

AmynthasIndex Terms--Genre/Form:

542853
Electronic books.

Bacterial Communities Under Soil Disturbance : = From Experimental Mixing in the Lab to Tillage and Bioturbation in the Field.
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520 $a Soil microhabitats are heterogeneous, disconnected, and isolated. Thus, soil supports a vast diversity of microbial inhabitants. How do physical disturbances-which disrupt soil microhabitats-affect bacterial community composition and community assembly processes (e.g., selection and dispersal)? Starting in the lab, we evaluated how bacterial communities are affected by soil mixing at various frequencies over a 16-week incubation. We hypothesized that soil mixing would decrease bacterial richness, and that community assembly would be driven by homogenizing dispersal and homogeneous selection. Using 16S rRNA gene sequencing, we found support for our hypotheses, and results further implied that the vast diversity observed in soil is a direct function of the generally unmixed, isolated nature of microbial communities. When we recapitulated this soil mixing experiment under anoxic conditions, findings corroborated the original study: soil mixing homogenized bacterial communities and increased fast growth potential, regardless of oxygen regime. Further, we found that the static anoxic environment decreased bacterial richness overall, and suppressed the influence of mixing-driven selection relative to the oxic treatment.We then took these fundamental ecological findings at the laboratory-scale, and applied them to field settings in southern Wisconsin under real-world soil mixing mechanisms, evaluating long-term tillage in agricultural soils and earthworm bioturbation in forested soils. With these field experiments, we specifically targeted the effects of disturbance on soil aggregation-which protects soil organic matter and promotes soil carbon persistence-and the bacterial communities that inhabit soil microaggregates. The effects of tillage mirrored those of the lab mixing experiments, resulting in more homogeneous soil bacterial communities, driven by homogenizing dispersal. However, bioturbation and aggregate generation due to the casting activity of non-native earthworms (co-occurring Amynthas tokioensis and A. agrestis) did not consistently impose a strong selective filter on the soil bacterial community. Despite high levels of activity in an otherwise relatively undisturbed forest environment, it does not seem that this earthworm activity necessarily acts to homogenize soil communities via dispersal. Further, we did not identify major distinctions between bacterial communities of the free microaggregate vs. occluded-within-macroaggregate microaggregate fractions in either the agricultural tillage study or the forest earthworm bioturbation study, thus suggesting that soil microaggregates readily shift between these operationally defined fractions, particularly at the end of the agricultural growing season, or in the presence of Amynthas spp. earthworms. With this work, we improve our understanding of the microbial response to soil disturbance, and thus the potential implications of increased soil disturbance under global change.
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653 $a Soil microbial ecology
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