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Date Permissions Signed


Date of Award

Summer 2017

Document Type

Masters Thesis

Degree Name

Master of Science (MS)


Environmental Sciences

First Advisor

Bunn, Rebecca

Second Advisor

Bauman, Jenise

Third Advisor

Lekberg, Ylva


In the U.S., Potentilla recta is an invasive, exotic forb. Previous research suggests that the soil microbes of native congeners (relatives within the same genus as P. recta) may inhibit P. recta, presumably because phylogenetically similar species may culture and be susceptible to similar pathogens. Our study aimed to answer three questions: (1) how do the fungal communities within the roots of P. recta compare to the fungal communities within the roots of neighboring congeners Potentilla gracilis and Drymocallis glandulosa (hereinafter referred to as the congeners) and native forbs, (2) what are the effects of the whole microbial community (microflora, microfauna, and some mesofauna mm), and the small microbial community (microflora, µm) on P. recta, (3) is there evidence that conspecific soil microbes mediate the distribution of P. recta in the field?

To address question one, we used high-throughput sequencing to compare the fungal communities within the roots of P. recta, its native congeners and neighboring forbs. To address our second question, we conducted a greenhouse experiment testing the effects of microbe fraction [none, small (< 20 µm), whole (< 2 mm)] and microbe source plant (congeners, forb, grass, and P. recta) on P. recta’s biomass. To address our third question, we observed and analyzed the distribution of P. recta in relation to its congeners in an intermountain grassland in Western Montana.

The fungal communities within the roots of P. recta and its congeners were different from other neighboring forbs, but pathogen abundance did not correspond to P. recta biomass. Further, the fungal communities within the roots of P. recta were unchanged by neighboring plant identity. In the greenhouse, we found reduced P. recta biomass from the whole microbial community collected from all source plants, but biomass did not differ significantly by source plant. Additionally, the magnitude of this negative effect was correlated with percent of colonization by arbuscular mycorrhizal fungi. We found neutral effects from the small microbe fraction, and no significant differences among source plant. In the field P. recta and other common grassland forbs were distributed at equal distances from the native congeners. We found no association between P. recta and the congeners co-occurring at the landscape scale. Overall, our results contradict previous findings and suggest that the direct and indirect effects of soil microbes on P. recta are nonspecific.





Western Washington University

OCLC Number


Subject – LCSH

Sulphur cinquefoil--Montana, Western--Geographical distribution; Cinquefoils--Montana, Western--Geographical distribution; Fungal communities--Montana, Western--Analysis

Geographic Coverage

Montana, Western




masters theses




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