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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Community and ecosystem changes in tallgrass prairie restorations: the effects of population source and diversity

Klopf, Ryan 01 May 2013 (has links) (PDF)
The overall objective of this study was to quantify the effects of dominant grass propagule source (i.e., cultivar vs. non-cultivar) and seeded diversity of propagules on community structure and ecosystem function during prairie restoration. Two field experiments, and two chronosequences were used to investigate this main objective. The two field experiments were established at the same latitude separated by 620 km (corresponding to a precipitation gradient from eastern Kansas to western Illinois), and consisted of a split plot design, with dominant grass source as the whole-plot factor (2 levels) and seeded dominance of grasses as the subplot factor (5 levels). Percent cover of each species in each treatment combination was quantified during the first five years of restoration. Total plant species richness and diversity were not adversely affected by cultivars in Kansas or Illinois. The effect of the dominant grass population source on the cover of focal grasses, planted species, and volunteer species were contingent upon location. By the fifth year of restoration, diversity and richness were greatest, and cover of volunteer species was lowest in the low grass dominance (i.e., high diversity) treatment. ANPP, as well as total, microbial, and mineralizable pools of C and N were measured to quantify ecosystem function in these two field experiments. Changes in ecosystem function in Kansas and Illinois were primarily driven by time and regional abiotic differences, not propagule source or seeded diversity. The effect of plant species diversity on ecosystem function was further investigated at a landscape scale by developing and sampling two chronosequences of high (HDC; n=20) and low diversity (LDC; n=15) prairies spanning over two decades of restoration in northwestern Illinois. In general most metrics of ecosystem function in both chronosequences moved towards levels measured in remnant prairies. While the constituent prairies of the HDC had higher species richness, diversity, and more rapidly increasing root biomass than the fields of the LDC, recovery of other important ecosystem functions including aboveground net primary productivity, total, microbial, and mineralizable soil C, and soil aggregate mean weighted diameter were achieved equally well with either high or low diversity prairie plantings.
142

Evidence of Climate Niche Creation in the Northern Great Plains: The History of Invasion, Population Genetics, Competitive Effect, and Long-Term Trends of Invasive Poa Pratensis L.

Dennhardt, Lauren Alexsandra January 2016 (has links)
Understanding the mechanisms of invasion is critical in order to control an invasive species. Poa pratensis L. (Kentucky bluegrass) is an invasive species that has been present in the northern Great Plains (NGP) for over 100 years, but has become a dominant species in the mixed grass region recently. My dissertation seeks to answer one critical question—why has P. pratensis become such a successful invasive species in the NGP? I first asked if the invasion was caused by adaptation and/or propagule pressure. I screened the genetic fingerprint of invasive P. pratensis in the NGP along with measuring the genomic content of wild plants and compared them to common cultivars. I found virtually no overlap between lawn cultivars and invasive P. pratensis populations. This was further supported by a narrow range of genomic content in wild individuals compared to the lawn cultivars. I also found no evidence of geographical patterning which is consistent with the hypothesis that local adaptation is not pervasive in P. pratensis. I then asked whether P. pratensis was a strong competitor compared to dominant plant species native to the tallgrass prairie. I studied competitive effect between Poa pratensis, Nassella viridula, Pascopyrum smithii, and Bouteloua gracilis through a species-pair competition experiment. Based on the relative interaction indices, P. smithii and P. pratensis were competitive against B. gracilis, and P. smithii was competitive against N. viridula. Additionally, P. pratensis was facilitated by all three species in the experiment. This study indicates that P. pratensis may be somewhat competitive. Finally, I asked whether the increase in the frequency of P. pratensis in the NGP may be attributed to environmental factors. In order to understand long-term correlations between P. pratensis invasion and environmental variables, I resampled plots that were previously sampled for species composition in 1978, 1979, and 1999. I found that P. pratensis levels did increase across plots and was corrrelated with higher levels of precipitation. My research indicates that increased precipitation in the NGP as a result of climate change is correlated with P. pratensis invasion in the NGP. / United States Fish and Wildlife Service (FWS-R6-POAPRATENSISGENETICS) / North Dakota State University. Department of Biological Sciences / North Dakota State University. Department of Natural Resource Management / North Dakota State University. Graduate School / Cross Ranch Fellowship
143

A Faunistic Survey Of Native Bees In The Mississippi Black Belt Prairie

McGee, Beverly A 03 May 2008 (has links)
This research presents the results of a bee survey (Hymenoptera: Apoidea) in remnants of the Mississippi Black Belt Prairie, a unique physiographical region that is a threatened community covering 14,141 square kilometers in both Mississippi and Alabama. Sampling was performed with sweep nets and Malaise traps. A total of 151 visits were made to several prairie remnant areas during the years 1999 – 2001 with 92 Malaise trap samples. Historical bee collection data from these prairies were incorporated into this survey. A total of 6,140 specimens resulting in 107 species, 51 new state records and eight disjunct species were collected within five bee families: Colletidae, Andrenidae, Halictidae, Megachilidae and Apidae. The most abundant species belonged to the Halictidae. The most common floral families visited were Asteraceae and Fabaceae. The addition of the species in this survey brings the state list of bees to at least 204.
144

Vegetation of the northern “Virginia military lands” of Ohio

Dobbins, Raymond Anson January 1937 (has links)
No description available.
145

A comparative sampling study of benthic invertebrate populations in a prairie stream

Petersen, Gene Leslie. January 1979 (has links)
Call number: LD2668 .T4 1979 P48 / Master of Science
146

An analysis of greater prairie-chicken demography in Kansas: the effects of human land use on the population ecology of an obligate grassland species

McNew, Lance B. Jr. January 1900 (has links)
Doctor of Philosophy / Department of Biology / Brett K. Sandercock / Greater prairie-chicken (Tympanuchus cupido) populations have been reduced by >70% since the turn of the 20th century due to large-scale conversion of native prairie habitats to cultivated agriculture and other human development. Although Kansas is considered a stronghold for greater prairie-chickens, statewide populations have declined >30% in the last 30 years. Goals of this dissertation were to determine the demographic mechanisms for apparent population declines and evaluate how regional variations in landscape composition and grassland management affect the demography, habitat use, life-history, and population viability of three populations of greater prairie-chickens. First, I found that, despite high reproductive potential, poor reproductive success prevented populations from being self-sustaining. All three populations were projected to decline but finite rates of population declines were different among populations (λ = 0.49, 0.54, and 0.74). I found that grassland fragmentation and rangeland management practices influence nearly every aspect of greater prairie-chicken population ecology and dynamics. A population in a contiguous prairie landscape managed with annual spring burning and intensive early stocking of cattle (South) was characterized by delayed breeding, low nest and brood survival (0.08–0.18 and 0.27, respectively), high annual survival of mature females (0.64–0.71), projected age-ratios heavily skewed toward adults, and longer generation times. Conversely, a population in grasslands heavily fragmented by cultivation and managed with longer fire-return intervals and moderate grazing (Smoky) initiated nests earlier, had higher nest and brood survival rates (0.16–0.31 and 0.34, respectively), produced significantly larger eggs, and had low annual survival (0.34–0.42) and shorter generation times. A site with intermediate levels of fragmentation, burning and grazing (North) had intermediate demography. Finite population change was more sensitive to changes in adult survival at all sites, but the relative influence of fecundity parameters on projected population change was not similar among study populations. Data indicate that differences in rates of decline among populations were largely due to variation in adult survival mediated by human landscape alteration. Human-mediated changes to grasslands impact the demography and viability of prairie-chicken populations, influence population sensitivities to changes in vital rates, and mediate changes in the life-history strategies of a grassland-sensitive species.
147

Field works: explorations in the tall grass prairie landscape

Wreford, Liz 11 April 2007 (has links)
‘FIELD WORKS’ explores landscape experiences that were once common to the tall grass prairie region of Manitoba. The route through this project winds in and out of urban surfaces to reveal memories embedded in the land. It documents forgotten and dormant prairie events so that they might be woven back into the fabric of the city. The purpose of this project is to transfer explored and speculative experience into a physical route through the urban prairie landscape. It is an effort to expose the layers clinging to physical memories rooted in the prairie. / May 2007
148

Population viability analysis of endangered plant species an evaluation of stochastic methods and an application to a rare prairie plant /

Kaye, Thomas N. January 2001 (has links)
Thesis (Ph. D.)--Oregon State University, 2001. / Includes bibliographical references.
149

Habitat use, demography, and population viability of disturbance-dependent shrubland birds in the Missouri Ozarks

Fink, Alix D. Dowling, January 2003 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.
150

Habitat use, demography, and population viability of disturbance-dependent shrubland birds in the Missouri Ozarks /

Fink, Alix D. Dowling, January 2003 (has links)
Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

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