Nutrient dynamics and fire history in mesquite (Prosopis spp.)-dominated desert grasslands of the southwestern United States

Persistent Link:
http://hdl.handle.net/10150/279975
Title:
Nutrient dynamics and fire history in mesquite (Prosopis spp.)-dominated desert grasslands of the southwestern United States
Author:
Wilson, Thomas Bachman
Issue Date:
2001
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
In desert grasslands of the southwestern United States, Prosopis velutina (mesquite), an N-fixing legume, has proliferated from historic drainage locations into more xeric grassland plains. This expansion is forming a more heterogenous soil nutrient topography in grasslands, N-pools are becoming localized under mesquite canopies, yet the rate and extent of this sequestration remains relatively unknown. Repeated prescribed burning has been used to control Prosopis distribution, but effects of fires on grassland soil nutrient distribution and aboveground plant biomass are also largely unknown. I examined recent research concerning P. velutina natural history, emphasizing characteristics that contribute to range expansion. I also evaluated Prosopis management practices---which include herbicide treatment, prescribed burning, grazing reduction, and mechanical removal---and management goals---which involve complete removal, no removal, and limited removal. Of these, limited removal is the most beneficial, using an herbicide application followed by periodic prescribed burning. In 1997 I established a study area at Fort Huachuca Military Reservation in southeastern Arizona, selecting two adjacent sites with similar soil composition and topography but different fire histories. I examined spatial and seasonal changes in composition and distribution of available soil N and litterfall. My results indicated these were more spatially and temporally heterogenous on sites with low fire frequency and high P. velutina stand development. In 1998 I selected nine sites at Fort Huachuca on two upland surfaces located < 1 km apart, with similar soil physical characteristics and fire frequencies ranging from 0 to 5 fires/decade. I evaluated relationships between fire frequency, soil nutrient status (pH, available P, organic C, total N, and available N), and aboveground plant biomass, including that of the non-native Eragrostis lehmanniana (Lehmann lovegrass). Soil pH and ammonium significantly decreased with increased fire frequency on one surface, and available P significantly decreased with increased fire frequency on the other surface. Available P and pH were significantly different between the 2 surfaces, but aboveground biomass was similar. Soil nutrient status and biomass were not related, suggesting plant-available soil nutrients may not control plant distribution or recovery following fire. E. lehmanniana biomass was negatively correlated with native grass and forb biomass, and tended to increase with increasing fire frequency. Surface litter and E. lehmanniana biomass were correlated, and may increase fire frequency, an important consideration when implementing grassland fire management practices.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Ecology.; Agriculture, Forestry and Wildlife.; Agriculture, Soil Science.; Agriculture, Range Management.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Soil, Water and Environmental Science
Degree Grantor:
University of Arizona
Advisor:
Thompson, Thomas L.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleNutrient dynamics and fire history in mesquite (Prosopis spp.)-dominated desert grasslands of the southwestern United Statesen_US
dc.creatorWilson, Thomas Bachmanen_US
dc.contributor.authorWilson, Thomas Bachmanen_US
dc.date.issued2001en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractIn desert grasslands of the southwestern United States, Prosopis velutina (mesquite), an N-fixing legume, has proliferated from historic drainage locations into more xeric grassland plains. This expansion is forming a more heterogenous soil nutrient topography in grasslands, N-pools are becoming localized under mesquite canopies, yet the rate and extent of this sequestration remains relatively unknown. Repeated prescribed burning has been used to control Prosopis distribution, but effects of fires on grassland soil nutrient distribution and aboveground plant biomass are also largely unknown. I examined recent research concerning P. velutina natural history, emphasizing characteristics that contribute to range expansion. I also evaluated Prosopis management practices---which include herbicide treatment, prescribed burning, grazing reduction, and mechanical removal---and management goals---which involve complete removal, no removal, and limited removal. Of these, limited removal is the most beneficial, using an herbicide application followed by periodic prescribed burning. In 1997 I established a study area at Fort Huachuca Military Reservation in southeastern Arizona, selecting two adjacent sites with similar soil composition and topography but different fire histories. I examined spatial and seasonal changes in composition and distribution of available soil N and litterfall. My results indicated these were more spatially and temporally heterogenous on sites with low fire frequency and high P. velutina stand development. In 1998 I selected nine sites at Fort Huachuca on two upland surfaces located < 1 km apart, with similar soil physical characteristics and fire frequencies ranging from 0 to 5 fires/decade. I evaluated relationships between fire frequency, soil nutrient status (pH, available P, organic C, total N, and available N), and aboveground plant biomass, including that of the non-native Eragrostis lehmanniana (Lehmann lovegrass). Soil pH and ammonium significantly decreased with increased fire frequency on one surface, and available P significantly decreased with increased fire frequency on the other surface. Available P and pH were significantly different between the 2 surfaces, but aboveground biomass was similar. Soil nutrient status and biomass were not related, suggesting plant-available soil nutrients may not control plant distribution or recovery following fire. E. lehmanniana biomass was negatively correlated with native grass and forb biomass, and tended to increase with increasing fire frequency. Surface litter and E. lehmanniana biomass were correlated, and may increase fire frequency, an important consideration when implementing grassland fire management practices.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Ecology.en_US
dc.subjectAgriculture, Forestry and Wildlife.en_US
dc.subjectAgriculture, Soil Science.en_US
dc.subjectAgriculture, Range Management.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineSoil, Water and Environmental Scienceen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorThompson, Thomas L.en_US
dc.identifier.proquest3010185en_US
dc.identifier.bibrecord.b41610957en_US
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