Ecosystem Consequences of Post-Fire Invasive Species in the Great Basin Desert
Prater, Margaret Rose
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/87050
Description
Title
Ecosystem Consequences of Post-Fire Invasive Species in the Great Basin Desert
Author(s)
Prater, Margaret Rose
Issue Date
2006
Doctoral Committee Chair(s)
Evan DeLucia
Department of Study
Plant Biology
Discipline
Plant Biology
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biogeochemistry
Language
eng
Abstract
Ecosystem processes are tightly linked to the structure and function of plant communities; therefore changes in the dominant vegetation will have important consequences for ecosystem function. Non-native plants, such as cheatgrass (Bromus tectorum L.), have aggressively invaded the Western United States. Promoted by overgrazing and fire, this invasion is rapidly converting large expanses of native sagebrush to post-fire invasive communities. The objective of this research was to test the general hypothesis that plant cover controls ecosystem function by quantifying the effect of land cover change on carbon, water and energy resources. Net carbon exchange (NCE), evapotranspiration (ET) and energy partitioning were measured in sagebrush and adjacent post-fire communities in the northern Great Basin Desert using a gas-exchange chamber and micrometeorological techniques. Temporal and spatial patterns of NCE and ET were correlated with changes in leaf area. Net C exchange and ET in post-fire communities dominated by perennial bunchgrasses was similar or greater than sagebrush. However, communities dominated by annuals (Bromus tectorum and Sisymbrium altissimum L.) had significantly lower NCE than sagebrush and became sources of carbon to the atmosphere with increased severity of the summer drought. Bunchgrasses partitioned more available energy into latent heat early in the season, resulting in greater ET, lower sensible heat flux and more rapid declines in surface soil moisture compared to sagebrush. These differences disappeared as surface soil moisture declined below 10%. DAYCENT, a daily time-step process-based ecosystem model, agreed well (R2 > 0.63, P < 0.01) with field-based measurements of NCE, ET and soil water content. While total annual ET was similar between sagebrush and post-fire Sisymbrium communities, increased evaporation in the annual community caused decreases in surface soil moisture. Lower productivity of annuals caused lower soil carbon storage compared to sagebrush. Replacement of native sagebrush with post-fire communities severely disrupted temporal and spatial patterns of carbon and water exchange, as well as long-term storage of ecosystem resources in these arid ecosystems. Understanding the disruption of carbon and water cycling in invaded ecosystems provides insight into controls on ecosystem function and provides a foundation for predicting future impacts of global change on arid ecosystems.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
