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The role of the exotic legume yellow...

Van Riper, Laura Carol.

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The role of the exotic legume yellow sweetclover (Melilotus officinalis) in a low nitrogen system: A potential ecosystem transformer and facilitator of invasion.

Record Type:	Electronic resources : Monograph/item
Title/Author:	The role of the exotic legume yellow sweetclover (Melilotus officinalis) in a low nitrogen system: A potential ecosystem transformer and facilitator of invasion./
Author:	Van Riper, Laura Carol.
Description:	177 p.
Notes:	Source: Dissertation Abstracts International, Volume: 66-03, Section: B, page: 1268.
Contained By:	Dissertation Abstracts International66-03B.
Subject:	Biology, Ecology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3167718
ISBN:	9780542036248

The role of the exotic legume yellow sweetclover (Melilotus officinalis) in a low nitrogen system: A potential ecosystem transformer and facilitator of invasion.
Van Riper, Laura Carol.

The role of the exotic legume yellow sweetclover (Melilotus officinalis) in a low nitrogen system: A potential ecosystem transformer and facilitator of invasion. - 177 p.

Source: Dissertation Abstracts International, Volume: 66-03, Section: B, page: 1268.

Thesis (Ph.D.)--University of Minnesota, 2005.

Single exotic species can change basic ecosystem processes and transform the ecosystems they have invaded. Nitrogen-fixing exotic species can alter nitrogen-cycling and facilitate the further invasion of other exotic species. This dissertation examines whether a short-lived, non-woody species common throughout a variety of habitats can act as a transformer of the nitrogen cycle and a facilitator of invasion. Yellow sweetclover (Melilotus officinalis) is an invasive, exotic, biennial legume that has become abundant in two historically low-nitrogen, perennial dominated ecosystems, western wheatgrass mixed-grass prairie and Badlands sparse vegetation. To address sweetclover's impact on grassland ecosystems and native plant communities this dissertation focuses on two questions: (1) Do sweetclover's nitrogen-fixing abilities cause it to act as a transformer by changing ecosystem nitrogen cycling through enriching nitrogen in a low nitrogen system? and (2) Do invasions by sweetclover and subsequent nitrogen enrichment facilitate the invasion and dominance of other exotic species? The effect of sweetclover was not consistent between the two ecosystems. Yellow sweetclover did act as a transformer and facilitator in the sparse habitats, but not in wheatgrass. In sparse vegetation, sweetclover increased soil nitrogen. Additionally, sweetclover was associated with increased cover and richness of both exotic and native species. In the harsh sparse environment, sweetclover acted as a facilitator and nurse plant. In the higher nitrogen wheatgrass habitat, sweetclover did not increase soil nitrogen and generally had no association with exotic species cover and richness. In wheatgrass, the impacts due to sweetclover were due more to its effects as a competitor than to effects on nitrogen cycling. Effects of an exotic nitrogen-fixing species must be examined within the context of the ecosystem and the current environmental conditions (such as precipitation levels). A species that has little impact in one ecosystem may be both a transformer and facilitator in another ecosystem or under different environmental conditions. Even short-lived nitrogen-fixing species, such as sweetclover, can alter ecosystems. It is recommended that sweetclover should not be planted purposefully and that management should be used to decrease sweetclover abundance.

ISBN: 9780542036248Subjects--Topical Terms:

1017726
Biology, Ecology.

The role of the exotic legume yellow sweetclover (Melilotus officinalis) in a low nitrogen system: A potential ecosystem transformer and facilitator of invasion.
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520 $a Single exotic species can change basic ecosystem processes and transform the ecosystems they have invaded. Nitrogen-fixing exotic species can alter nitrogen-cycling and facilitate the further invasion of other exotic species. This dissertation examines whether a short-lived, non-woody species common throughout a variety of habitats can act as a transformer of the nitrogen cycle and a facilitator of invasion. Yellow sweetclover (Melilotus officinalis) is an invasive, exotic, biennial legume that has become abundant in two historically low-nitrogen, perennial dominated ecosystems, western wheatgrass mixed-grass prairie and Badlands sparse vegetation. To address sweetclover's impact on grassland ecosystems and native plant communities this dissertation focuses on two questions: (1) Do sweetclover's nitrogen-fixing abilities cause it to act as a transformer by changing ecosystem nitrogen cycling through enriching nitrogen in a low nitrogen system? and (2) Do invasions by sweetclover and subsequent nitrogen enrichment facilitate the invasion and dominance of other exotic species? The effect of sweetclover was not consistent between the two ecosystems. Yellow sweetclover did act as a transformer and facilitator in the sparse habitats, but not in wheatgrass. In sparse vegetation, sweetclover increased soil nitrogen. Additionally, sweetclover was associated with increased cover and richness of both exotic and native species. In the harsh sparse environment, sweetclover acted as a facilitator and nurse plant. In the higher nitrogen wheatgrass habitat, sweetclover did not increase soil nitrogen and generally had no association with exotic species cover and richness. In wheatgrass, the impacts due to sweetclover were due more to its effects as a competitor than to effects on nitrogen cycling. Effects of an exotic nitrogen-fixing species must be examined within the context of the ecosystem and the current environmental conditions (such as precipitation levels). A species that has little impact in one ecosystem may be both a transformer and facilitator in another ecosystem or under different environmental conditions. Even short-lived nitrogen-fixing species, such as sweetclover, can alter ecosystems. It is recommended that sweetclover should not be planted purposefully and that management should be used to decrease sweetclover abundance.
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