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Patterns of soil phosphorus: Concen...

Bennett, Elena Michele.

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Patterns of soil phosphorus: Concentrations and variability across an urbanizing agricultural landscape.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Patterns of soil phosphorus: Concentrations and variability across an urbanizing agricultural landscape./
作者:	Bennett, Elena Michele.
面頁冊數:	142 p.
附註:	Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 2004.
Contained By:	Dissertation Abstracts International63-04B.
標題:	Agriculture, Soil Science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3049416
ISBN:	0493639578

Patterns of soil phosphorus: Concentrations and variability across an urbanizing agricultural landscape.
Bennett, Elena Michele.

Patterns of soil phosphorus: Concentrations and variability across an urbanizing agricultural landscape. - 142 p.

Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 2004.

Thesis (Ph.D.)--The University of Wisconsin - Madison, 2002.

Eutrophication, the overenrichment of aquatic ecosystems with nutrients such as phosphorus (P), is a major cause of reduced freshwater quality. The primary source of P to most lakes is nonpoint source runoff. Runoff is not generated evenly across a watershed; instead, the majority is generated in a few critical source areas. Understanding the location of critical source areas is a significant step toward managing P runoff to aquatic ecosystems.

ISBN: 0493639578Subjects--Topical Terms:

1017824
Agriculture, Soil Science.

Patterns of soil phosphorus: Concentrations and variability across an urbanizing agricultural landscape.
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245 1 0 $a Patterns of soil phosphorus: Concentrations and variability across an urbanizing agricultural landscape.
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500 $a Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 2004.
500 $a Supervisor: Stephen R. Carpenter.
502 $a Thesis (Ph.D.)--The University of Wisconsin - Madison, 2002.
520 $a Eutrophication, the overenrichment of aquatic ecosystems with nutrients such as phosphorus (P), is a major cause of reduced freshwater quality. The primary source of P to most lakes is nonpoint source runoff. Runoff is not generated evenly across a watershed; instead, the majority is generated in a few critical source areas. Understanding the location of critical source areas is a significant step toward managing P runoff to aquatic ecosystems.
520 $a Urban-rural gradients are one method for predicting soil P. I compare several measures of a nonlinear urban-rural gradient to other predictors of soil P in Dane County, Wisconsin, USA. Most of the factors expected to drive differences in soil P concentrations were not found to be good predictors of soil P. While there were several significant relationships, most explained only a small proportion of the variation. High variability in soil P concentrations made accurate prediction difficult.
520 $a Human activity may change variance patterns by shifting the scale at which governing processes are operating or the governing processes that are dominant at a given scale. I measured soil P concentrations and variability at three scales across four management regimes. Variance changed across scale in each management regime and across management regimes at the same scale. Variance within a field was lower in human-dominated sites than in prairies. Intensely used sites are more homogeneous and have higher P concentrations than prairies: they are more likely to be critical source areas.
520 $a In ecological studies, there are often many regressions that have similar goodness-of-fit statistics. Choosing one model as “best” may discard important information in models that fit almost as well. A technique based on bootstrapping was used to solve this problem for predictions of soil P in Dane County. Bagging, which aggregates the predictions of many well-fitting models, improved prediction accuracy and enhanced assessment of prediction uncertainty and variability.
520 $a Effective eutrophication management will require knowledge of soil P accumulation patterns. The three techniques for understanding soil P concentrations and variability that I examined demonstrated that predicting P concentrations is difficult; however, it may be possible to predict critical source areas using information about variability.
590 $a School code: 0262.
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791 $a Ph.D.
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