Degree Type

Thesis

Date of Award

1-1-2006

Degree Name

Master of Science

Major

Ecology and Evolutionary Biology

Abstract

Do host plant species, in particular prairie forbs, associate with the same arbuscular mycorrhizal (AM) fungal species at various locations within the Midwestern prairie states? And, do different plant species within a site have similar AM fungal communities, or is there a high degree of host-specificity? If prairie forbs do associate with similar fungal species at various locations or are host-specific, we may be able to apply that knowledge to prairie reconstructions and increase the establishment of forb species. Well-established prairie seed production plots of three commercial nurseries in Iowa, Wisconsin, and Minnesota, in the tallgrass prairie region of the Midwestern U.S., were sampled in October 2004. Soil cores for analysis of AM spores, root samples for determination of AM colonization, and soil samples were collected from monospecific plots of five prairie forbs, Heuchera richardsonii R. (Alumroot), Veronicastrum virginicum L. (Culver's root), Silphiumperfoliatum L. (Cup plant), Ratibida pinnata (Vent.) (Yellow/Gray-headed Coneflower), and Hypericum pyramidatum L. (St. John's Wort). Spores of AM fungi were extracted from the soil samples and were identified by morphological characteristics. Over all three sites and all plant species, spores of 35 AM fungal species were found in the soil cores, representing six genera. Plant species all showed evidence of mycorrhizal infection and roots were at least 34% colonized by AM fungi. There were no significant relationships between the number of fungal species in a plot and the soil pH or content of P, NH₄, or NO₃⁻. Overall, 43% of fungal species found were ubiquitous and 17% were exclusive to a particular site. Over all sites, yellow coneflower had the highest mean fungal species richness (26.3), significantly higher (p<.005) than Culver's root (19.3), which had the lowest richness. Over all plant species, fungal community similarity between pairs of sites was on average 51.3% (using Sorenson's index). Fungal community similarity between pairs of sites for any one plant species ranged from 80 to 96%, with a mean of 86.3%. Similarity between pairs of plant species within any one site varied from 69 to 93%, with a mean of 85.5%. Fungal communities were very similar both within individual prairie forb species regardless of field site and within a field site regardless of forb species. There were very few species found exclusively with one plant species or at one site; most of the fungi were generalists and exhibited little host-specificity, and all plant species had a substantial number of fungal associates.

Copyright Owner

Bree Suzanne Surges

Language

en

OCLC Number

76942713

File Format

application/pdf

File Size

77 pages

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