Dissertations and Theses @ UNI
Award Winner
Recipient of the 2004 Outstanding Master's Thesis Award - Second Place.
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Availability
Open Access Thesis
Keywords
Forbs--Hardiness--Iowa; Prairie conservation--Iowa;
Abstract
Thousands of hectares of warm-season grass plantings in Iowa have few to no native forbs. Diversifying these species poor plant communities with native prairie forbs could result in increased resistance to climatic extremes, increased biodiversity, reduced noxious "weedy" plant invasion, and reduced geographic isolation between existing native prairie remnants.
I hypothesized that frequent mowing in the first one or two years after broadcasting forb seed into an established stand of warm-season grasses can increase forb emergence and reduce forb mortality. I further hypothesized that fall seeded forbs would establish better that those seeded in spring.
To test my hypothesis, I seeded 23 forb species at a rate of 3.7 kg/ ha or 350 viable seeds/ m2. I assessed and compared forb emergence and mortality using three mowing treatments and two seeding treatments; fall seeding with frequent mowing the first growing season (mow-1), spring seeding with frequent mowing the first growing season (mow-ls) winter seeding with frequent mowing two consecutive growing seasons (mow-2), and fall seeding without mowing (no-mow). I also destructive sampled forb plants to assess growth differences between mow-1 and no-mow treatments.
Over time, forb emergence was significantly (p<0.020) higher in mowed plots in year one. Year two forb emergence was not significantly different among treatments. Seeding time was not a significant factor in forb emergence in year one and in year two. Species richness was significantly (p<0.031) higher in no-mow plots in year one. Species richness was not significantly different among mowing treatments in year two. Seeding time was not a significant factor in species richness in year one and in year two. Over time, forb mortality was significantly (p<0.047) greater in no-mow plots in year one. In addition, forb mortality was significantly (p<0.038) greater in no- mow plots over-winter (between year one and year two). Over-winter mortality in no-mow plots was 24.3% compared to 2.3% in mow-1 and 3.9% in mow-2 plots. Year two mortality was not significantly different among mowing treatments. Forbs in mow-1 plots destructive sampled in September of both years had significantly (p<0.001) taller shoots and deeper roots and significantly (p<0.001) greater root and shoot mass than no-mow plants. By September year two, forbs in mow-1 plots averaged 223% taller shoots and 45% deeper roots over forbs sampled in no-mow plots. In year two, there were 46 times more flowering plants in mow-1 plots than in no-mow plots.
Year of Submission
2002
Year of Award
2004 Award
Degree Name
Master of Science
Department
Department of Biology
Department
Tallgrass Prairie Center
First Advisor
Laura Jackson, Co-Chair, Thesis Committee
Second Advisor
Daryl Smith, Co-Chair, Thesis Committee
Date Original
12-2002
Object Description
1 PDF file (ix, 180 pages)
Copyright
©2002 Dave Williams
Language
en
File Format
application/pdf
Recommended Citation
Williams, Dave, "Emergence and mortality of native prairie forbs seeded into an established stand of grasses" (2002). Dissertations and Theses @ UNI. 592.
https://scholarworks.uni.edu/etd/592
Comments
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