Dissertation
MONITORING ECOLOGICAL INTEGRITY IN THE CANYON GRASSLANDS: PLANT SPECIES AND ECOSYSTEM INDICATORS
Doctor of Philosophy (PhD), Washington State University
01/2014
Handle:
https://hdl.handle.net/2376/111838
Abstract
Our objectives were to identify relationships between ecological integrity of the plant community, including the rare perennial forb Silene spaldingii Wats. (Spalding's catchfly), and external variables such as cattle grazing and weather, in the canyon grasslands in southeast Washington. From 3-5 years of data, we selected indicators from 200+ plants and functional groups measured by canopy and soil cover, frequency, and species richness metrics. Selected indicators differed between five ecological sites that were experimentally grazed for two to three years and ungrazed for more than five years on two units. From 2009 to 2011, we also compared 30 plant community variables between sites that contained the threatened Silene spaldingii and otherwise comparable sites without the plant using logistic regression. We regressed Silene spaldingii counts and reproductive effort against a combination of plant community and weather variables.
Ecological integrity was generally stable or decreased during our study on grazed and ungrazed pastures at both units and on Silene spaldingii habitat. We identified increases in cover and species richness of exotic total species, exotic and native annual forbs, native perennial forbs, soil surface and bare soil, but indicators were not clearly associated with cattle grazing. Silene spaldingii absence was associated with higher cover of total exotic species, native annual forbs, and exotic annual forbs and grasses. Variation in Silene spaldingii counts and reproductive effort were associated with increases in native annual forb cover, exotic annual grass and forb species richness and cover, and exotic perennial grass species richness. Multiple plant community and Silene spaldingii variables were associated with weather, indicating the importance of understanding these relationships when considering ecological integrity, experimental grazing, and rare plant populations. Results indicate that managers should monitor the cover and species richness of exotic and annual species to understand changes in ecological integrity and Silene spaldingii demographics. If sites cross a threshold into a degraded annual-dominated state, integrity of the ecosystem may be permanently lost.
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Details
- Title
- MONITORING ECOLOGICAL INTEGRITY IN THE CANYON GRASSLANDS: PLANT SPECIES AND ECOSYSTEM INDICATORS
- Creators
- Laura Marie Heinse
- Contributors
- Linda H Hardesty (Advisor)Lisa A Shipley (Committee Member)J. Richard Alldredge (Committee Member)Karen L Launchbaugh (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 148
- Identifiers
- 99900581445401842
- Language
- English
- Resource Type
- Dissertation