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Kingdon, Lorraine B. "Native Grass for Lawns." College of Agriculture, University of Arizona (Tucson, AZ), 1990. http://hdl.handle.net/10150/295643.
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Cerney, Dawna Lynn. "Two methods of harvesting native grass community seed." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0015/MQ48244.pdf.
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Holmberg, Kyle B. "SELECTION FOR REDUCED SEED DORMANCY IN SEVEN NATIVE GRASS SPECIES." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11052007-220827/.
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Lowland switchgrass (Panicum virgatum), big bluestem (Andropogon gerardii), indiangrass (Sorghastrum nutans), upland switchgrass (Panicum virgatum), little bluestem (Schizachyrium scoparium), beaked panicum (Panicum capillare), and purpletop (Tridens flavus) all show strong signs of seed dormancy which contributes to extremely poor field establishment. The objective of this work was to reduce seed dormancy by selecting individuals that exhibited reduced pre-stratification dormancy in laboratory tests. The classical breeding method of phenotypic recurrent selection was used to enhance germination. Of the three tall-stature species, lowland switchgrass made the greatest improvement in pre-stratification germination, followed by indiangrass and big bluestem. The four short stature species have shown various results after one cycle of selection at Starkville. A field emergence trial was also conducted to evaluate three cycles of breeding seed with five commercially available cultivars in which Cycle 3 seed produced more plants per hectare than any of the other cultivars or germplasm.
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Stone, Kenley Michelle. "Evaluation of native grass sod for stabilization of steep slopes." Thesis, Montana State University, 2005. http://etd.lib.montana.edu/etd/2004/stone/StoneK0505.pdf.
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Ghajar, Shayan M. "The Suitability of Native Warm-Season Grasses for Equine." Diss., Virginia Tech, 2020. http://hdl.handle.net/10919/99084.
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Introduced cool-season grasses are dominant in Virginia's grasslands, but their high digestible energy and non-structural carbohydrate (NSC) levels pose a risk for horses prone to obesity and laminitis. Native warm-season grasses (NWSG) have lower digestible energy and NSC levels that may be more suitable for horses susceptible to laminitis. The overall objectives of this research were to 1) assess voluntary intake, toxicological response, and apparent digestibility of NWSG hays fed to horses; 2) evaluate the characteristics of three NWSG species under equine grazing; and 3) evaluate establishment strategies for NWSG and wildflowers in Virginia. For the first objective, a hay feeding trial was conducted with 9 Thoroughbred geldings in a 3 x 3 Latin square design. Voluntary dry matter intake of indiangrass (Sorghastrum nutans) and big bluestem (Andropogon gerardii) hays by horses were 1.3% and 1.1% of BW/d, significantly lower than orchardgrass (Dactylis glomerata), an introduced cool-season grass, at 1.7% of BW/d. Biomarkers for toxicity remained within acceptable ranges for all treatments. Apparent DMD did not differ among hays, ranging from 39 to 43%. Non-structural carbohydrate levels were below the maximum recommended concentration for horses susceptible to laminitis. For the second objective, a grazing trial was conducted comparing indiangrass (IG), big bluestem (BB), and eastern gamagrass (Tripsacum dactyloides) (EG) yields, forage losses, changes in vegetative composition, and effects on equine bodyweight. Nine, 0.1-hectare plots were seeded with one of the three native grass treatments, and each plot was grazed by one Thoroughbred gelding in two grazing bouts, one in July and another in September 2019. Indiangrass had the highest available forage, at 4340 kg/ha, compared with 3590 kg/ha from BB (P < 0.0001). Eastern gamagrass plots established poorly, and had only 650 kg/ha available forage during the experiment. Grazing reduced standing cover of native grasses in IG and BB treatments by about 30%, and trampled forage constituted 36-68% of groundcover in those plots after each grazing bout. Horses lost weight on all treatments, but tended (P=0.09) greater weight loss on the indiangrass treatment at 1.5 kg/d compared to 0.5 kg/d in the BB and EG treatments. For the third objective, three experiments were conducted to evaluate different strategies for establishing NWSG and wildflowers. The first experiment compared large grazed plots with or without a 2 oz/acre rate of the herbicide imazapic. Imazapic led to higher biomass and percent cover in plots seeded only with NWSG. For plots seeded with a mix of NWSG and wildflowers, imazapic reduced wildflower establishment and resulted in higher biomass and percent cover of weeds over the course of the experiment. The second experiment examined four rates of imazapic application for NWSG and wildflower establishment in small plots seeded with either NWSG or a NWSG and wildflower mix, and found biomass and percent cover of weeds was lowest at a 6 oz/acre rate, while NWSG biomass and cover did not differ between treatments. Wildflower establishment was again reduced by imazapic. The third establishment experiment compared four site preparation strategies for wildflower establishment and found tillage resulted in the most cover and biomass of wildflowers.Doctor of Philosophy
Introduced cool-season grasses are dominant in Virginia's grasslands, but their high digestible energy and non-structural carbohydrate (NSC) levels pose a risk for horses prone to obesity and laminitis. Native warm-season grasses (NWSG) have lower digestible energy and NSC levels that may be more suitable for horses susceptible to laminitis. The overall objectives of this research were to 1) assess voluntary intake, toxicological response, and apparent digestibility of NWSG hays fed to horses; 2) evaluate the characteristics of three NWSG species under equine grazing; and 3) evaluate establishment strategies for NWSG and wildflowers in Virginia. For the first objective, a hay feeding trial was conducted with 9 Thoroughbred geldings in a 3 x 3 Latin square design. Voluntary dry matter intake of indiangrass (Sorghastrum nutans) and big bluestem (Andropogon gerardii) hays by horses were 1.3% and 1.1% of BW/d, significantly lower than orchardgrass (Dactylis glomerata), an introduced cool-season grass, at 1.7% of BW/d. Biomarkers for toxicity remained within acceptable ranges for all treatments. Apparent DMD did not differ among hays, ranging from 39 to 43%. Non-structural carbohydrate levels were below the maximum recommended concentration for horses susceptible to laminitis. For the second objective, a grazing trial was conducted comparing indiangrass (IG), big bluestem (BB), and eastern gamagrass (Tripsacum dactyloides) (EG) yields, forage losses, changes in vegetative composition, and effects on equine bodyweight. Nine, 0.1-hectare plots were seeded with one of the three native grass treatments, and each plot was grazed by one Thoroughbred gelding in two grazing bouts, one in July and another in September 2019. Indiangrass had the highest available forage, at 4340 kg/ha, compared with 3590 kg/ha from BB (P < 0.0001). Eastern gamagrass plots established poorly, and had only 650 kg/ha available forage during the experiment. Grazing reduced standing cover of native grasses in IG and BB treatments by about 30%, and trampled forage constituted 36-68% of groundcover in those plots after each grazing bout. Horses lost weight on all treatments, but tended (P=0.09) greater weight loss on the indiangrass treatment at 1.5 kg/d compared to 0.5 kg/d in the BB and EG treatments. For the third objective, three experiments were conducted to evaluate different strategies for establishing NWSG and wildflowers. The first experiment compared large grazed plots with or without a 2 oz/acre rate of the herbicide imazapic. Imazapic led to higher biomass and percent cover in plots seeded only with NWSG. For plots seeded with a mix of NWSG and wildflowers, imazapic reduced wildflower establishment and resulted in higher biomass and percent cover of weeds over the course of the experiment. The second experiment examined four rates of imazapic application for NWSG and wildflower establishment in small plots seeded with either NWSG or a NWSG and wildflower mix, and found biomass and percent cover of weeds was lowest at a 6 oz/acre rate, while NWSG biomass and cover did not differ between treatments. Wildflower establishment was again reduced by imazapic. The third establishment experiment compared four site preparation strategies for wildflower establishment and found tillage resulted in the most cover and biomass of wildflowers.
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McGinley, Susan. "Saltgrass Could Be New Turf Variety: Native Grass Tolerates Drought, Salt, Traffic." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2002. http://hdl.handle.net/10150/622247.
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Munter, Emily J. "Seasonal prescribed fire effects on cheatgrass and native mixed grass prairie vegetation /." Chadron, Neb. : Chadron State College, 2008. http://www.nlc.state.ne.us/epubs/G1000/B134-2008.pdf.
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Thesis submitted to the graduate faculty of Chadron State College in partial fulfillment of the requirements for the degree of Master of Arts in Education."October, 2008". Includes bibliographical references (p. 59-64). Also available in PDF via the World Wide Web.
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Hely, Sara Elizabeth Lorraine Biological Earth & Environmental Sciences Faculty of Science UNSW. "The responses of C4 invasive grass Eragrostis curvula and C3 native grass Austrodanthonia Racemosa under elevated CO2 and water limitation." Awarded by:University of New South Wales, 2008. http://handle.unsw.edu.au/1959.4/35671.
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The concentration of atmospheric carbon dioxide (CO2) in the atmosphere has increased by 35% since pre-industrial levels. Projections for the next 100 years indicate an increase to levels between 490 and 1260 parts per million by volume (ppm) of CO2, equating to a 75 % to 350 % increase in concentration since the year 1750. Associated with this increase in [CO2] will be a 1.4 to 5.8?? C increase in lower atmospheric temperature. While past research has attempted to address the effects of such climatic changes on individual plant responses, predictions of plant responses at the ecosystem level are still highly uncertain. Difficulties lie in the enormous variation of plant responses to climate change variables among and within species, and between and within environmental conditions. Past research assumed that plants using either the C3 or C4 metabolic pathways would respond differently but predictably to climate-change variables based on their metabolic pathway. Recent evidence has suggested however, that the added interactions of external environmental variables and species-specific sensitivities to climate change make it difficult to predict plant and ecosystem responses to climate change. To investigate the mechanisms behind responses of Australian grasses to climate change, 2 pot experiments was conducted using growth cabinets to compare the effect of elevated CO2 and water-limitation on the invasive C4 grassland plant, Eragrostis curvula (E. curvula), native Australian C3 grassland plant, Austrodanthonia racemosa (A. racemosa), and wheat species, Triticum aestivum (T. aestivum). The experiment was run at ambient levels of CO2 maintained at 390 ppm compared to elevated levels of 740 ppm. Imposed restrictions to water supply consisted of gradually drying the soil down to 30 % available soil water (ASW) followed by re-wetting to 50 % ASW. Well-watered conditions for the experiment consisted of gradually drying the soil down to 50 % ASW, followed by rewetting to 95 % ASW. Plants were grown in mixtures and monocultures, consisting of 9 plants equally spaced in a grid design. The three significant findings of the thesis were that: 1) the metabolic pathway (C3 versus C4) was not always an accurate predictor of biomass accumulation under elevated CO2 in the plants studied. Previous research suggested that CO2-stimulation of photosynthesis in C3 plants would lead to greater increases in biomass under elevated CO2 compared to C4 plants, though both C3 and C4 plants could benefit from any reduction in stomatal conductance under dry conditions at elevated CO2. The results from the experiments in this thesis showed a strongly significant biomass response to elevated CO2 in both dry and wet conditions for C4 grass E. curvula. The C3 grass A. racemosa in dry conditions, did not. It was speculated that without the CO2-induced water conservation effect, the C3 grass experienced photosynthetic down-regulation and this precluded a positive biomass response under elevated CO2. 2) the magnitude and direction of biomass response to elevated CO2 was dependant on factors such as resource-availability and the phenotypic variability of the plants species. 3) critical analysis of results from this thesis, combined with past research on plant responses under elevated CO2 showed a tendency for researchers to repeatedly test plants from the Poaceae family, or close relatives of the Poaceae family. As a result, when past data were corrected for this lack of independence, there was no relationship between the evolution of the C3 and C4 metabolic pathway and biomass response to elevated CO2. Instead, other factors (such as growth rate, plant height, leaf number, etc) were presented as being more important in determining biomass response. These observations were supported by results found in this thesis.
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Trunzo, Juliana P. "Native Small Mammal Use of an Invasive Grass: Heermann's kangaroo rats (Dipodomys heermanni) and Veldt grass (Ehrharta calycina) in Coastal California." DigitalCommons@CalPoly, 2015. https://digitalcommons.calpoly.edu/theses/1405.
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Invasive species are generally regarded as detrimental to native communities because they cause increased competition and community structure alterations. There is therefore a critical need to understand the ecological processes underlying the establishment and spread of invasive species. While most studies to date have focused on the role of competition in species invasions, trophic dynamics may also play a fundamental role in the establishment and spread of non-natives, especially in cases when a non-native species experiences differential predation pressure relative to a native competitor. Herein I explore the potential for differential granivory pressure by a native rodent (Heermann’s kangaroo rat, Dipodomys heermanni arenae) on native shrubs and an invasive plant (Veldt grass, Ehrharta calycina). Veldt grass, a perennial tufted grass native to South Africa and introduced to California in 1929, is highly invasive, and the shift of native coastal dune scrub to a grassland, dominated by Veldt grass, is considered one of the factors that led to the decline of the federally endangered Morro Bay kangaroo rat. However, kangaroo rats are largely graminivores (consume grass seed) and are known to consume invasive grasses and other plants. Differential seed preferences for native and Veldt seed were examined by placing feeding stations containing each seed type in habitats dominated by either native plants or Veldt grass. Each feeding station was monitored using motion-activated game cameras and the amount of each seed type collected by nineteen individually-marked, wild kangaroo rats was documented. These marked kangaroo rats were monitored both in native and Veldt grass habitats, allowing for the testing of habitat origin (Native vs. Veldt), sex (male or female) and seed type on the amount of seed taken. Nine of the kangaroo rats harvested Veldt grass seed. Though females collected more seed than males, there was no difference between the amounts (% of available seed) of Veldt grass and native seed collected. Habitat of origin (i.e., habitats with Veldt grass present or habitats without Veldt grass) had no effect on the amount of seed collected or the type of seed collected. During seed station trials, kangaroo rats were also recorded removing seed heads from naturally occurring Veldt grass stalks, providing clear documentation that Heermann’s kangaroo rats do collect Veldt grass seed. Accompanying laboratory seed preference trials were also conducted to confirm the consumption of Veldt grass seed. These controlled laboratory trials revealed that Heermann’s kangaroo rats will consume Veldt grass seed, although Veldt grass seed was consumed in smaller amounts (g) than millet and sunflower seed, which were presented simultaneously. These findings indicate that non-native Veldt grass may provide an additional or alternative source of seed for kangaroo rats, which could provide a partial explanation for why kangaroo rats are able to survive in monocultures of Veldt grass.
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Day, Toby Richard. "Intermountain West native and adapted grass species and their management for turfgrass applications." Thesis, Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/day/DayT0806.pdf.
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Gaskin, Sharyn, and sharyn gaskin@flinders edu au. "Rhizoremediation of hydrocarbon contaminated soil using Australian native grasses." Flinders University. Medicine, 2009. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20090820.111303.
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The breakdown of contaminants in soil resulting from microbial activity that is enhanced in the presence of the plant root zone, rhizosphere, has been termed rhizoremediation. To date, Australian native plants have not been assessed for their hydrocarbon rhizoremediation potential. The use of native plants offers an economically feasible and environmentally sustainable cleanup option for the rehabilitation and restoration of hydrocarbon contaminated sites in Australia. The aim of the study was to evaluate the potential of Australian native grass species for the rhizoremediation of aliphatic hydrocarbon contaminated soil from a mine site.
Candidate Australian native grass species Poaceae were selected following the development of essential and desirable growth criteria. Nine perennial Australian grasses were evaluated for seedling emergence in sandy loam soil sourced from a mine site which was artificially contaminated with a 60:40 diesel/oil mix at concentrations of 30 000 mg/kg, 10 000 mg/kg, 5 000 mg/kg and 0 mg/kg control. Seedling emergence was not adversely affected by the presence of hydrocarbon contamination at the exposed concentrations for eight of the nine species studied p > 0.05. Three promising species were assessed for relative growth performance in diesel/oil contaminated 10 000 mg/kg, 5 000 mg/kg and uncontaminated control soils in greenhouse studies to assess their tolerance of aliphatic hydrocarbon contaminated soil.
Cymbopogon ambiguus Lemon Scented grass is a summer growing perennial with widespread distribution throughout Australia including the region where the mine site is situated. Brachiaria decumbens Signal grass naturalised - is adapted to humid tropical areas of Australia and is native to the site and sourced from seed banks. Microlaena stipoides Weeping grass var. Griffin is a cool season grass, widely distributed throughout Australia in moister regions. The three evaluated species survived for 120 days in the diesel/oil contaminated soil at the exposed concentrations without adverse growth affect p > 0.05. In some instances e.g. C. ambiguus growth stimulation occurred in the presence of contamination producing significantly more root biomass compared with the control p < 0.0001.
Most hydrocarbon degradation is believed to occur through microbial processes, and so the plant-associated microbial community was examined in the three tolerant species. The assessment of the influence of grass on the abundance and activity of microorganisms in the rhizosphere revealed species-specific plant-induced changes in the soil microbial community. Selective enrichment of hydrocarbon degrading microorganisms was demonstrated in the rhizosphere soil of the Australian grasses tested, to varying degrees. C. ambiguus appeared to have the greatest influence on stimulation of hydrocarbon degrading microorganisms, followed by the cool season grass M. stipoides. B. decumbens showed consistently lower numbers of hydrocarbon degrading microorganisms in rhizosphere soil over time compared to the other two species p < 0.01. The influence of grasses on microbial community structure - defined as community DNA fingerprint - in diesel/oil contaminated soil suggested no new microbial population was favoured by the grasses - qualitative shift - rather there were relative quantitative changes in existing members of the microbial population. Soil lipase activity did not appear to be an optimal bioindicator of rhizoremediation and may encompass total soil microbial activity not exclusively the hydrocarbon degrading microorganisms of interest.
The assessment of biodegradation of hydrocarbons in soil is essential to characterise the effectiveness of plant species in rhizoremediation. Residual diesel and oil concentrations as total petroleum hydrocarbons, TPH were measured using Gas Chromatography. The presence of single species successfully enhanced the removal of hydrocarbons from soil for all species. All showed significantly lower residual hydrocarbon concentrations than those in unplanted soil after 100 days p < 0.01. Significantly, it was not necessary to add N and P to achieve up to 90% reduction in hydrocarbon concentrations in the soil. The relative performance of each grass species varied. In soil planted with C. ambiguus hydrocarbon concentrations were reduced faster and to a greater extent than the other species studied, from 10 000 mg/kg to approximately 1 100 mg/kg TPH, 88% removal. Similar endpoint success was recorded for M. stipoides which facilitated 80% reduction in hydrocarbon concentrations. Interestingly, B. decumbens, the only naturalised species, did not perform as well as the other species, although still significantly better compared to unplanted controls, with hydrocarbon concentrations reduced to approximately 4 500 mg/kg, 49%. Hydrocarbon concentrations in unplanted control soil were reduced by 45% through natural biodegradation processes. Plant root and shoot tissue was periodically assessed for hydrocarbon accumulation and was shown to be negligible. A multispecies planted trial using C. ambiguus plus B. decumbens had no additional influence on total TPH removal. The final TPH removal efficiency in the multispecies trial was not significantly different p > 0.05 from that of the best single species performer of the two i.e. C. ambiguus. In a field application the planting of multiple species may still be desirable in order to preserve site biodiversity and assist rehabilitation of the area.
A strong relationship between abundance of hydrocarbon degrading microorganisms in the rhizosphere and hydrocarbon biodegradation was demonstrated for all species p < 0.01. Those species which showed greatest stimulation of the microbial population resulted in enhanced TPH removal from soil. These species were the summer grass C. ambiguus and the winter species M. stipoides. This may allow for broader application both seasonally and geographically across Australia. B. decumbens showed successful rhizoremediation to a lesser degree, but may still be an option in multiple planting strategies.
This investigation identified three Australian grass species from the nine evaluated that are candidates for further investigation for in situ rhizoremediation potential at field scale.
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Lehr, Gavin Charles, and Gavin Charles Lehr. "Symbiosis in the Context of an Invasive, Non-Native Grass: Fungal Biodiversity and Student Engagement." Thesis, The University of Arizona, 2018. http://hdl.handle.net/10150/626728.
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Grasslands in the western United States face severe environmental threats including those brought about by climate change, such as changes in precipitation regimes and altered fire cycles; land-use conversion and development; and the introduction, establishment, and spread of non-native species. Lehmann’s lovegrass (Eragrostis lehmanniana) was introduced to the southwestern United States in the early 1900s. Since its introduction, it has become the dominant grass in the mid-elevation grasslands of southern Arizona, including the Santa Rita Experimental Range (SRER), where it has displaced native grasses including Arizona cottontop, three awns, and gramas. Like all plants in terrestrial ecosystems, this grass harbors fungal symbionts that can be important for its establishment and persistence. This thesis focuses on fungal symbionts of Lehmann’s lovegrass and has two components. First, the diversity and distributions of endophytes in Lehmann’s lovegrass are evaluated in the context of biotic and abiotic factors in the SRER. Culturing from roots and shoots of Lehmann’s lovegrass at points beneath and outside the canopy of native mesquites, which are encroaching on grasslands over time, provides insight into how a single plant species can exhibit local variation in the composition of its symbionts. Second, the thesis is used as the basis for engagement of students in science, technology, engineering, and mathematics (STEM) through the development and implementation of classroom- and field activities centered on endophytes, which help high school students address core learning aims while also gaining real research experience. Engaging students in important questions relevant to their local environment can catalyze interest in science and help students cross the threshold into research. The contributions of such approaches with respect to learning not only fulfills key next-generation science standards and common core objectives, but provides students with a meaningful introduction to the excitement, importance, and accessibility of science.
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Ambrose, Laura G. "Seed persistence of an introduced and a native grass species in a prairie old field." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ45313.pdf.
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Porter, Shane Warren. "Comparative nitrogen partitioning and water use by native and introduced grass communities in Southern Alberta, Canada." Diss., Montana State University, 2005. http://etd.lib.montana.edu/etd/2005/porter/PorterS1205.pdf.
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The objectives of this research were to evaluate 1) short-term changes in soil and plant N partitioning created by cultivating and re-seeding native grasslands with two cropping systems of wheat and perennial (crested wheatgrass and Russian wildrye) monocultures; 2) differences in the rate of soil water uptake between Mixed Prairie grasslands, crested wheatgrass and Russian wildrye after a dry-down period; and 3) differences in above ground water use efficiencies, root and crown masses between Mixed Prairie grasslands, crested wheatgrass and Russian wildrye under two different soil water contents. The perennial agronomic species were recommended by Agriculture and Agrifood Canada for seeding in Mixed Prairie and Fescue grassland in southern Alberta, Canada. In the first four years after plow-down, soil nitrate (NO₃-) concentration was higher and light fraction N (LFN) was lower in the soil under wheat than native grasslands. Although LFN was lower in perennial monocultures than native grasslands, there was little difference in soil nitrate. More N was partitioned into shoot biomass of wheat, crested wheatgrass and bromegrass that native grasslands and levels increased as annual and long-term growing season precipitation increased. There were no differences in the rate of soil water uptake after dry-down periods between native Mixed Prairie, crested wheatgrass or Russian wildrye, but both perennial monocultures had higher above ground water use efficiencies than native Mixed Prairie.
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Garner, Alan Brad. "High-Density Grass Carp Stocking Effects on a Reservoir Invasive Plant, Water Quality, and Native Fishes." NCSU, 2008. http://www.lib.ncsu.edu/theses/available/etd-09132008-145505/.
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Stocking grass carp Ctenopharyngodon idella is a commonly applied technique used to control nuisance aquatic vegetation in reservoirs. Factors that influence the degree of aquatic vegetation control are stocking density, regional climate, abundance and species composition of the aquatic plant community, and relative grass carp feeding preferences for the plant species. We evaluated high-density grass carp stocking in a reservoir for control of parrot-feather (Myriophyllum aquaticum, an invasive aquatic plant that is not preferentially consumed by grass carp) and the associated effects on water quality and native fishes. Lookout Shoals Lake, a piedmont North Carolina reservoir, was stocked with triploid grass carp at a density of 100 fish per vegetated hectare. Parrot-feather biomass in the lake was significantly reduced three months after grass carp stocking, compared to biomass in in-situ exclosures. During the second year after grass carp stocking, parrot-feather biomass in the lake compared to biomass in in-situ exclosures indicated continued control, but unexplained lack of growth within most experimental exclosures precluded biomass analyses. Increases in ambient water chlorophyll a, reactive phosphorus, and nitrate-nitrite concentrations were measured after grass carp stocking. We evaluated the native fish community using seasonal shoreline electrofishing before and after grass carp stocking. Total catch for all fish species in aggregate at shoreline transects was not significantly different after grass carp stocking by number or biomass. Catch rates of largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and redbreast sunfish Lepomis auritus were not significantly different after grass carp stocking, but yellow perch Perca flavescens catch rates were significantly lower. The biological significance of fish distribution changes and long-term effects on lake biota remain undetermined. Our results demonstrate that intensive grass carp stocking can control an invasive aquatic plant that is not preferentially consumed by grass carp, and reveal associated changes in water quality and fish distributions.
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Holthuijzen, Maike F. "Grass-Shrub Spatial Associations Over Precipitation and Grazing Gradients in the Great Basin, USA." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4486.
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Plant spatial patterns have been studied to gain insight into plant interactions such as competition and facilitation (positive plant interactions). The stress gradient hypothesis predicts that as environmental stress increases facilitation dominates, while competition dominates in less stressful conditions.
Beneficial plants (nurses) can create favorable abiotic conditions for subanopy plants. Additionally, palatable herbaceous species growing under nurse shrub canopies benefit from physical protection.
I investigated spatial associations between Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) and three native grasses (Poa secunda, Elymus elymoides, and Pseudoroegneria spicata) across a rainfall gradient in the Great Basin, USA. I also explored the effect of grazing on grass-shrub spatial associations. I hypothesized that positive shrub-grass spatial associations would become more frequent at lower rainfall levels; I further hypothesized that 1) at intermediate levels of stress, positive grass-shrub spatial associations would dominate and 2) at extreme levels of stress, positive grass-shrub spatial associations and interactions would no longer dominate. At high moisture stress, the addition of grazing stress may limit the nurse’s ability to provide to benefits to subcanopy plants.
Cover of P. secunda was greater in shrub canopy microsites than interspaces at low to moderate levels of rainfall. Cover and density of E. elymoides were greater in sagebrush canopies over most rainfall levels. Elymus elymoides and P. spicata were taller and narrower in basal width and less likely to be grazed in canopy versus interspace microsites.
I next investigated the effects of grazing intensity over a rainfall gradient and found a significant interaction of rainfall and microsite on P. secunda cover. Poa secunda formed positive interactions with A. tridentata at lower rainfall levels, regardless of grazing intensity. Its cover was significantly greater in interspaces at high rainfall compared to low rainfall sites. Elymus elymoides density was greater in canopy vs. interspace microsites, regardless of rainfall level or grazing intensity.
Plant spatial associations can indicate which nurse microsites are favorable to plant growth and may improve seeding or planting success during ecological restoration. My results suggest that exploiting sagebrush canopy microsites for restoration of native perennial grasses would improve plant establishment, growth or survival particularly in drier areas.
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Dittmer, Drew E., and Joseph R. Bidwell. "Herpetofaunal Species Presence in Buffel Grass (Cenchrus ciliaris ) versus Native Vegetation‐Dominated Habitats at Uluṟu‐Kata Tjuṯa National Park." Digital Commons @ East Tennessee State University, 2018. https://doi.org/10.1111/aec.12557.
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Buffel grass (Cenchrus ciliaris ) has been established in Uluṟu‐Kata Tjuta National Park since 1968. To date, the influence of buffel grass on the Park's flora and fauna has been largely unassessed. The objectives of this study were to determine if buffel grass dominates vegetation communities at the base of Uluṟu and if buffel grass habitats are associated with lower reptile and amphibian species richness than endemic vegetation communities. We used vegetation transects to measure the amount of buffel grass and genera of endemic vegetation at 26 sampling locations around the base of Uluṟu. The vegetation survey data were paired with pitfall trap data from reptile and amphibian captures at the same sampling locations. Indicator species analysis and non‐metric multidimensional scaling were used to analyse the vegetation and herpetofaunal community data. Our analyses determined five distinct vegetation communities around Uluṟu. At the base of Uluṟu, buffel grass dominated half of sampled areas and the rest of the inselberg's base was dominated by Themeda grasses. Buffel grass habitats had significantly higher herpetofaunal species richness than the Themeda habitats that dominated other areas at Uluṟu's base. Herpetofauna species richness in buffel grass‐dominated habitats was also significantly higher than all vegetation communities except for Triodia‐dominated habitats. These observations do not directly indicate that buffel grass presence promotes higher species richness of reptiles and amphibians since the observed patterns may be driven by factors such as proximity to breeding sites and abiotic variables not directly related to the grass itself.
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Atkin, Bridget M. "Establishment and Aesthetic Value of Native Grass, Legume, and Forb Species for Grassland Restoration in the Northern Intermountain West." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/837.
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Interest in the restoration of landscapes native to the Intermountain West is growing as the value of these arid ecosystems is increasingly recognized. Many landscapes within the Intermountain region have been impacted by grazing, development, recreation, and other human-caused disturbances. The complex relationships within the native plant communities of these arid landscapes need to be well-understood biologically, while considering their aesthetic contribution, if restoration efforts are to succeed. Although the use of ecologically appropriate native species is increasing in popularity, there is discontinuity between aesthetics and meaningful ecological contributions. A series of studies was designed to aid in the restoration of a site located at the Utah Botanical Center in Kaysville, Utah. The restoration site is situated along the I- 15 corridor which interfaces urban development. The high visibility and educational purpose of the site requires that aesthetic as well as ecological concerns are addressed in the restoration of the native plant community. Specifically, the establishment of Intermountain grassland species was assessed using a variety of methods to test establishment rates as well as the potential value to the system of biologically fixed nitrogen provided by native legumes early within the establishment period.
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Karbaschi, Mohammad Reza. "Structural, physiological and molecular characterisation of the Australian native resurrection grass Tripogon loliiformis (F.Meull) C.E.Hubb during dehydration and rehydration." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/90050/1/Mohammad%20Reza_Karbaschi_Thesis.pdf.
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There is an urgent need to develop crops that can withstand future climates. Results from this thesis demonstrated that a native Australian resurrection grass exhibits structural, physiological and metabolic strategies to tolerate drying. These strategies may be utilized for the generation of stress tolerant crops.
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Joseph, Tony. "The response of photosynthesis and respiration of a grass and a native shrub to varying temperature and soil water content." Thesis, University of Canterbury. School of Biological Sciences, 2011. http://hdl.handle.net/10092/6685.
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In New Zealand, native shrubs are considered an important potential carbon-sink in disturbed or abandoned land (e.g., pastoral land that is unsustainable for long-term pastoral agriculture). However, the impact of varying environmental drivers on carbon uptake from photosynthesis and carbon loss from respiration of a developing shrubland remains uncertain. In this study, the effects of both temperature and soil water content (θ) on photosynthesis and respiration were examined under controlled growth cabinet and field conditions in a pasture grass and the native shrub, kānuka (Kunzea ericoides var. ericoides). The purpose of the investigation was to assess the combined impacts of varying temperature and θ on canopy processes and to disentangle the effects of θ on photosynthesis and respiration for the two different plant types.
A controlled growth cabinet study (Chapter 2) showed that θ had a greater effect on the short-term temperature response of photosynthesis than the temperature response of respiration. The optimum value of θ for net photosynthesis was around 30 % for both kānuka and the grass. Statistical analysis showed that the temperature sensitivity of photosynthetic parameters was similar for both plant types, but the sensitivity of respiratory parameters was different. Reduction in θ induced an inhibition of photosynthetic capacity in both plant types. The response of respiratory parameters to θ was not related to substrate limitations, however available evidence suggests that it is likely to be a species dependent plant mechanism in regulating the cost of maintenance due to reduced photosynthate assimilation and decreasing energy supply to support the activity of respiratory enzymes.
Results obtained from a field study (Chapter 3) showed that photosynthesis and respiration in the grass and kānuka were sensitive to seasonal changes in temperature and θ. Photosynthetic parameters showed little acclimation following changes in seasonal growth conditions. In contrast, respiratory parameters tended to acclimate more strongly. Respiratory acclimation to multiple environmental conditions was characterised by changes in temperature sensitivity and a shift in the response of respiration to temperature, demonstrating the involvement of both ‘Type I’ and ‘Type II’ acclimation in both plant types.
The results from controlled growth cabinet and field studies were used to drive a leaf level model that integrates the responses of photosynthesis and respiration to changes in temperature and θ and incorporates acclimation using variable photosynthetic and respiratory parameters (Chapter 4). This model was used to estimate the annual canopy carbon exchange of the grass and kānuka in response to seasonal changes and to predict changes in canopy carbon exchange under varying future climate change scenarios. The model highlighted the importance of considering seasonally-acclimated parameters in estimating canopy carbon exchange of both plant types to concurrent changes in multiple environmental variables.
The overall results support the conclusion that understanding the combined effects of environmental variables on canopy processes is essential for predicting canopy net carbon exchange of a pasture-shrub system in a changing global environment. It has been shown here that the rate of increase in photosynthesis with increasing θ is greater than that of respiration which results in a progressively greater apparent carbon gain at moderate values of θ. Moreover, the impact of lower values of θ, which reduced the apparent sensitivity of respiration to temperature, may effectively decrease the rate of respiration during warmer summer months and enhance thermal acclimation via downregulation of respiration. Therefore, considering the influence of soil water conditions on the temperature sensitivity of photosynthetic and respiratory model parameters has important implications for precisely predicting the net carbon exchange of a pasture-shrub system.
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Mack, Wyatt Mackenzie. "Grassland Birds Community Dynamics, Resource Selection, and Nest Survival on Mixed-Grass Prairie Grazed by Native Colonial and Domestic Herbivores." Thesis, North Dakota State University, 2017. https://hdl.handle.net/10365/28598.
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Investigators surveyed avian and vegetation composition on- and off- black-tailed prairie dog (Cynomys ludovicianus; hereafter prairie dog) colonies to gain greater insight into community dynamics of grassland passerines. Few studies have investigated grassland bird community associations with prairie dogs, and of those limited studies aim to quantify nesting passerine habitat selection and nest success. The objective of this study was to identify community associations and factors that shape the community of grassland birds on grazed mixed-grass prairie, both on- and off-prairie dog colonies. Bird and vegetation communities, avian densities, nesting survival, and resource selection was investigated in relativity to a landscape occupied with prairie dogs. Individual species exhibited different selections in regards to different vegetation communities created by prairie dogs. This makes heterogeneity an important landscape component for maintaining diverse, robust bird and plant communities at the landscape scale.National Institute of Food and Agriculture (NIFA) (Grant 2011-68004-30052)
United State Department of Agriculture (USDA)
North Dakota State University (NDSU)
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Summerhays, Jan C. R. "Effects of Non‐Surface‐Disturbing Treatments for Native Grass Revegetation on Cheatgrass (Bromus tectorum L.) Metrics and Soil Ion Availabilities." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1024.
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Several restoration methods intended to increase the success of aerially‐seeded perennial grasses were assessed to determine their effects on cheatgrass metrics and soil nutrient bioavailabilities. These methods were: 1) imazapic herbicide application (140 g ai ∙ ha‐1, 210 g ai ∙ ha‐1, and no application [control]), 2) vegetation manipulation treatments (50% sagebrush overstory thinning, 100% sagebrush overstory thinning, sagebrush overstory and/or vegetative thatch burning, and no manipulation [control]), and 3) alternative seeding treatments (aerial seeding with raking, aerial seeding with activated carbon [AC] addition, aerial seeding with sucrose addition, and regular aerial seeding [control]). Treatments were arranged in 3‐way factorial designs, which allowed main effects and interactions between treatments to be assessed. Responses were followed for two growing seasons following treatment.
Main effects of treatments and their interactions on cheatgrass metrics are described in Chapter 2. Herbicide reduced cheatgrass weights and tiller and spikelet numbers in 2009, but these variables were greater than in no‐herbicide plots in 2010. Burning decreased cheatgrass densities but increased weights and tiller and spikelet numbers in both years. One hundred percent sagebrush thinning resulted in greater cheatgrass weights and tiller and spikelet numbers in both years and greater densities in 2010. Sucrose addition decreased cheatgrass weights and tiller and spikelet numbers in 2009, but increased these variables in 2010. An interaction between AC and herbicide treatment was observed, with AC potentially sequestering and lessening the negative effect of herbicide on cheatgrass. Aerial seeding with raking and 50% sagebrush thinning treatments were not found to significantly affect cheatgrass either year.
The effects of treatments (herbicide, 50% sagebrush thinning, aerial seeding on snow, and aerial seeding with raking treatments omitted) on soil nutrient availabilities are described in Chapter 3. We used ion exchange resin (IER) membrane probes to measure extractable quantities of 15 ions over three time periods following treatment applications. Burning resulted in short‐term increases in many soil nutrient availabilities, including nitrate (NO3 ‐), phosphate (H2PO4 ‐), and sulfate (SO4 2‐). Sucrose addition reduced availabilities of NO3 ‐ and H2PO4 ‐ during the first winter and growing season. No changes were detected with AC addition or 100% sagebrush thinning during any sampling time.
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Soares, Sílvia Maria Pereira. "Banco de sementes, chuva de sementes e o uso de técnicas de nucleação na restauração ecológica de uma clareira dominada por Melinis minutiflora P. Beauv." Universidade Federal de Juiz de Fora (UFJF), 2009. https://repositorio.ufjf.br/jspui/handle/ufjf/3933.
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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Melinis minutiflora (Poaceae) é uma espécie de origem africana que tem causado grandes problemas em ambientes naturais no Brasil. Ela é uma espécie exótica invasora muito agressiva e de difícil controle. Em Juiz de Fora, MG, ela domina uma área de clareira antrópica no interior da Reserva Biológica Municipal Santa Cândida. Este trabalho teve como objetivos avaliar o potencial de regeneração dessa clareira, através da caracterização do banco de sementes e da chuva de sementes e avaliar o potencial de diferentes métodos de restauração ecológica baseados na nucleação. O banco de sementes foi quantificado em 12 amostras sob árvores (SP) e 12 em locais abertos, sob capim (SC), com dimensões de 25x25x3cm. A quantificação das sementes foi feita através da germinação, acompanhada por 4 meses em casa de vegetação. No interior da clareira foram capinados 10 transectos de 2,5x15m, onde foram instaladas 10 parcelas com os seguintes tratamentos: controle (sem capina), capina (regeneração autóctone), capina e transposição de solo (regeneração alóctone), monitoramento da chuva de sementes (coletores de 1m²) e plantio de mudas, todos monitorados durante 12 meses. As amostras para a transposição do solo foram coletadas sob a vegetação do entorno da clareira, em 10 parcelas de 1,0x0,5x0,1m aleatoriamente alocadas, essas foram espalhadas em 10 parcelas de 1,0x1,0m. Foram plantadas mudas de Schinus therebinthifolius, Trema micrantha e Virola bicuhyba em 3 diferentes tratamentos, com 5 repetições, compondo parcelas com apenas uma muda (P1); parcelas com 3 mudas da mesma espécie (P2) e parcelas com 3 mudas, sendo uma de cada espécie (P3). O banco de sementes apresentou uma densidade média de 12.646,67 ± 9.428,06 sementes/m2, sendo que 93% eram da família Poaceae. Não houve diferença significativa na densidade do banco de sementes entre amostras oriundas de SP e SC. SP apresentou menor diversidade (H’ = 0,22) que SC (H’ = 0,39). Em ambas as condições houve o predomínio de espécies herbáceas. Na chuva de sementes foram amostrados 140.701 diásporos com predominância de espécies anemocóricas e herbáceas, sendo que 93% dos diásporos pertencem a M. minutiflora. Na regeneração autóctone foi amostrada, no último mês de monitoramento, uma densidade de 57,2 ± 52,4 plantas/m², foram identificadas 39 espécies, com a predominância de herbáceas, sendo que as mais abundantes, depois de M. minutiflora, foram Borreria alata, Sida glaziovii e Crotalaria pterocaula. Na transposição do solo, a densidade média amostrada no último mês de monitoramento foi de 46,7 ± 41,8 plantas/m², sendo reconhecidas 66 espécies, com a predominância de herbáceas, e poucos representantes de espécies arbóreas como Apuleia leiocarpa, Cecropia sp, Croton urucurana, e Trema micrantha. Mudas de S. therebinthifolius e T. micrantha apresentaram um bom crescimento em altura e diâmetro, que não diferiram estatisticamente entre P1, P2 e P3. A taxa de mortalidade foi nula para S. therebinthifolius, de 20% para T. micrantha, em especial no tratamento P2, e de 88% para V. bicuhyba. Todos os tratamentos, com exceção do plantio de mudas, apresentaram a dominância de espécies herbáceas e a forte presença de M. minutiflora, mostrando que o manejo do capim-gordura é necessário para acelerar a regeneração na clareira.
Melinis minutiflora (Poaceae) is an African species that has been a big problem in natural environments in Brazil. It is an invader exotic species that is very aggressive and its control is difficult. In Juiz de Fora, MG, it dominates an anthropic gap area in the Biological Reserve Santa Cândida. The objectives of this work were to evaluate the natural regeneration by characterization of the seed bank and seed rain of this gap and evaluate the potential of different restoration ecology methods based on nucleation. The seed bank was quantified in 12 samples under trees (SP) and 12 ones in opened places, under grass (SC), with dimensions of 25x25x3cm. The seeds quantification was made through germination, monitored during 4 months in green house. Inside of the gap were weeded 10 transects of 2,5x15m, where were installed 10 parcels with the following treatments: control (without weeding), weeding (autochthonous regeneration), seed rain monitoring (traps of 1m²) and the planting, all monitored during 12 months. The soil transposition samples were collected under around vegetation of the gap in 10 parcels of 1,0x0,5x0,1m allocated randomly, these were spread in 10 parcels of 1,0x1,0m. Schinus therebinthifolius, Trema micrantha and Virola bicuhyba plants were planted in 3 different treatments with 5 repetitions compounding parcels with only one plant (P1); parcels with 3 plants of the same species (P2) and parcels with 3 plants with one of each species (P3). The seed bank showed a density of 12.646,67 ± 9.428,06 seeds/m2 that 93% of the plants were of Poaceae family. There was not significant difference in seed bank density of SP and SC samples. SP presented less diversity (H’ = 0,22) than SC (H’ = 0,39). In both conditions there was herbaceous species predominance. In the seed rain were sampled 140.701 seeds with anemochorous and herbaceous predominance, being that 93% of the seeds belong to M. minutiflora. In the autochthonous regeneration was sampled, in the last monitored month, a density of 57,2 ± 52,4 plants/m², were identified 39 species with herbaceous predominance, being that the most abundant, after M. minutiflora, were Borreria alata, Sida glaziovii and Crotalaria pterocaula. In the soil transposition, the last monitored month density was 46,7 ± 41,8 plants/m², being recognized 66 species with herbaceous predominance and a few representative tree species like Apuleia leiocarpa, Cecropia sp, Croton urucurana, and Trema micrantha. S. therebinthifolius and T. micrantha plants showed a good height and diameter growth that had not a statistical difference between P1, P2 and P3. The mortality rate was null to S. therebinthifolius, of 20% to T. micrantha, especially in the P2 treatment, and of 88% to V. bicuhyba. All treatments, except planting, presented the herbaceous species domain and the strong presence of M. minutiflora, showing that the molasses grass management is necessary to accelerate the gap regeneration.
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Scholles, Carlos Eduardo Meneghetti. "Discursive and mediatic battles in Thomas King's Green Grass, Running Water." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2010. http://hdl.handle.net/10183/28206.
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O objetivo desta dissertação é o de investigar as disputas pelo poder subjacentes no texto literário do autor cherokee/canadense Thomas King, mais especificamente em seu romance publicado em 1993 intitulado Green Grass, Running Water. Serão destacadas as estratégias performáticas empregadas na desconstrução de representações opressivas de nativo-americanos por discursos ocidentais que compõem um complexo campo de batalha onde vozes em conflito disputam por direitos discursivos nas relações de poder. Se por um lado temos a tradição epistemológica positivista/cartesiana que trabalha há cinco séculos no sentido de exercer controle sobre as representações simbólicas dos nativo-americanos, a fim de que poder executivo e discursivo possa ser exercido sobre eles, por outro lado temos que Thomas King proporciona ao leitor o acesso a uma estrutura cíclica, não hierarquizada da narrativa e do epistêmio nativo-americanos. Esta investigação irá apontar os momentos de conflito entre essas vozes e analisará uma potencial interpretação democrática, de terceira via para esses encontros aparentemente binários. Espera-se ser possível indicar que Green Grass, Running Water propicia um privilegiado campo simbólico para que conflitos culturais e epistemológicos possam ocorrer e ser resolvidos com alguma espécie de resolução positiva em relação ao aspecto frequentemente belicoso dos engajamentos nativos e ocidentais. Para tanto, investigaremos a tradição bíblica e judaico-cristã de hierarquização e como o processo de nomeação de indivíduos e categorias permite que ocorra uma relação de dominação. Discutiremos a estrutura organizacional das comunidades, baseando-nos nas proposições de Zygmunt Bauman, com o intuito de averiguar de que forma o texto literário lida com questões como o pertencimento a grupos que possuem critérios subjetivos de aceitação, permitindo-nos responder se tais critérios permitem uma opção de filiação ou se representam uma demanda coletiva opressiva sobre o indivíduo. Uma análise dos discursos científicos de verdade também será feita, contrastando-os com a construção mítica coletiva das narrativas nativo-americanas como construções alternativas de verdade. Finalmente, teremos um capítulo sobre o poder narrativo da fotografia (mídia presente no romance em diversos momentos), no qual os usos da câmera serão descritos e analisados em seus potenciais de malícia e de narração distorcida.The aim of this paper is to investigate the power struggles underlying the literary text of Canadian/Cherokee author Thomas King in the novel Green Grass, Running Water, published in 1993. We will highlight the performative strategies employed in the deconstruction of oppressive representations of the Native American by Western discursive and mediatic voices. The novel offers an interweaved narrative of Native and Western cultural materials that, together, will compose a complex battlefield of contentious voices that, ultimately, weigh on the balance of power relations to claim discursive rights. On the one hand, we have the epistemological tradition of a Positivist/Cartesian logic that has been working for five centuries to hold sway over the symbolic representations of the Native Americans in order to exert executive and discursive power over them; on the other hand, Thomas King provides the reader a glimpse of the cyclical, non-hierarchized structure of Native narrative and episteme. This investigation will point out the moments of conflict between these two voices and attempt to elaborate on the potential democratic/third-way interpretation of these seemingly binary encounters. We hope to be able to indicate that Green Grass, Running Water provides a privileged symbolic battleground for cultural and epistemological clashes to occur and be settled with some sort of positive resolution to the long-lasting contentious nature of Native and Western engagements. In order to accomplish that, we will delve into the biblical and Judeo-Christian tradition of hierachization and how the process of naming of individuals and categories allows for domination to occur. We will elaborate on the structural organization of communities, based on the propositions of Zygmunt Bauman, in order to assess how the literary text handles issues such as belonging to groups that have subjective criteria for acceptance, aiming at answering whether these criteria allow for an option of membership or if they pose as oppressive collective demands over the individual. An analysis of the scientific discourses of truth will also be provided, contrasting them with the collective mythmaking of Native American narratives as alternative constructors of truths. Finally, we will have a chapter on the narrative power of photography (a medium present in the novel at various moments), in which the uses of the camera are described and analyzed in their guileful and (mis)narrating potentials.
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Reinwald, Alexandra D. "Effects of Non-Surface-Disturbing Restoration Treatments on Native Grass Revegetation and Soil Seed Bank Composition in Cheatgrass-Invaded Sagebrush-Steppe Ecosystems." DigitalCommons@USU, 2013. http://digitalcommons.usu.edu/etd/1537.
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The conversion of sagebrush-steppe communities of the Great Basin into cheatgrass-dominated communities is one of the most dramatic ongoing land conversions in North America. Although restoration of these communities is a high priority to landowners and land management agencies, restoration of native vegetation is difficult. Several restoration treatments intended to increase the success of aerially‐seeded perennial grasses in cheatgrass-invaded sagebrush ecosystems were assessed to determine their effects on perennial seedling emergence and soil seed bank density and composition. Assessed restoration treatments were: 1) vegetation manipulation (sagebrush thinning and prescribed burning); 2) imazapic herbicide application; 3) seedbed amendments (aerial seeding with activated carbon addition, aerial seeding with sucrose addition); and 4) seeding frequency. The effects of these treatments were evaluated in two distinct sagebrush shrubland ecosystems in northern Utah. One is characterized as a remnant sagebrush stand with a cheatgrass-dominated understory and the other as a cheatgrass near-monoculture, completely lacking a sagebrush component. In the seed bank study, responses were assessed immediately and 1 year following treatment while in the seedling emergence study, they were assessed 2 and 3 years following treatment. Main effects of vegetation manipulation, herbicide application, and seedbed addition treatments and their interactions on perennial seedling emergence are described in Chapter 2. The effects of seeding frequency on perennial seedling emergence are also described in Chapter 2. Herbicide demonstrated potential for increasing native perennial grass emergence, although this response was delayed and not seen until 3 years post-application. Burning showed potential for increasing the emergence of perennial grasses 2 years post-burn. Results also suggest that potential exists to increase native perennial grass emergence through an increase in seeding frequency. In Chapter 3 I evaluated the effects of vegetation manipulation, herbicide application, and seedbed addition on seed pool dynamics. These results suggest that herbicide and sucrose may be useful tools for reducing exotic species richness in cheatgrass-invaded systems. Herbicide also showed potential for reducing cheatgrass seed bank densities. Additionally, results demonstrated that the reductions in cheatgrass seed bank densities observed immediately after fire are still observed 1 year post-burn.
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Voss, Joshua C. "Forage Adaptability Trials for Forage and Seed Production in Bolivia; Effect of 5 Herbicides on 7 Native Utah Forbs." BYU ScholarsArchive, 2006. https://scholarsarchive.byu.edu/etd/1121.
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The harsh environmental and poor economic conditions of the Bolivian Altiplano require intervention to assist many of those that live there to become economically self-sufficient. We attempted to find introduced dry season reserve forage grasses that could produce enough biomass to be useful as feed for livestock, and that could also produce enough seed to distribute to farmers. While some of the grasses produced reasonable amounts of biomass, none produced seed in quantities that would be even close to being economically viable. The most likely cause of this is that the timing of resources that the grasses need to flower is very different between Bolivia and the areas from which the grasses originally came. We concluded that either the conditions under which the grasses are grown would need to be changed (i.e., earlier irrigation), or pre-adapted native species should be used. Native forbs are a critical component of any natural ecosystem, and thus should be included in wildland restoration projects. However, because the seed is currently collected by hand from the wild, it is very expensive, and this limits the ability of land managers to utilize it. A possible solution to this dilemma is for growers to commercially produce the seed and thus drive down the cost. In such a situation, it would be necessary to use herbicides to control competing weeds. We analyzed the effects of 5 herbicides on 7 species of native Utah forbs at 3 growth stages to learn which herbicides could safely be used on the test plants. We found that the plants' reaction the herbicides is largely species- and growth-stage specific.
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Davis, Joshua Samuel. "Laughter in the Americas: Native American Humor in Almanac of the Dead, Bearheart, and Green Grass, Running Water." Kent State University Honors College / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1557496462044708.
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Paulus, Rosani Inês. "Caracterização morfológica e métodos para superação de dormência de sementes de Randia armata." Universidade Federal de Pelotas, 2005. http://repositorio.ufpel.edu.br/handle/ri/1363.
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Previous issue date: 2005-12-16The study was carried through in a fishery of changes, in the city of Missal, State of Parana, in order to study the morphological characteristics of the plant, flower, fruit, seed and seedlings of lemon grass, Randia armata (De Candolle SW.) and treatments to overcome seed dormancy. To break dormancy study we used an experimental design of randomized blocks with four treatments, using 150 seeds in each treatment, six replicates of 25 seeds, totaling 600 seeds. Treatments consisted of untreated seeds (seeds washed in running water), mechanical scarification (sandpaper No. 100), heat (immersion in hot water at 80 ° C) and acid scarification (immersion in concentrated sulfuric acid 98% for ten minutes) . The seeds were subsequently submitted to germination in tubes. Through daily evaluations, we determined the percentage of germinated seeds and emergence speed index at 120 days. Randia armata is a woody shrub or small tree with thorns on the trunk. The fruit is fleshy, globe-shaped and the seed is surrounded by viscous mucilage. Germination is epigeous. Scarification with sulfuric acid proved the most effective treatment to promote germination of seeds of lemon grass.
O estudo foi realizado em viveiro de mudas, no município de Missal, Estado do Paraná, com o objetivo de estudar as características morfológicas da planta, flor, fruto, semente e plântula de limão do mato, Randia armata (De Candolle SW.) e tratamentos para superação da dormência das sementes. Para o estudo de superação da dormência empregou-se delineamento experimental em blocos ao acaso com quatro tratamentos, utilizando 150 sementes em cada tratamento e seis repetições de 25 sementes, totalizando 600 sementes. Os tratamentos consistiram em sementes não tratadas (sementes lavadas em água corrente), escarificação mecânica (lixa d água nº 100), térmico (imersão em água quente a 80ºC) e escarificaçao ácida (imersão em ácido sulfúrico concentrado 98% por dez minutos). As sementes foram posteriormente submetidas à germinação em tubetes. Através de avaliações diárias, determinou-se a percentagem de sementes germinadas e o índice de velocidade de emergência aos 120 dias. Randia armata é uma arvoreta com espinhos lenhosos no tronco. O fruto é carnoso, de forma globosa e a semente está envolta em mucilagem de consistência viscosa. A germinação é do tipo epígea. A escarificação com ácido sulfúrico revelou-se o tratamento mais eficiente para promover a germinação de sementes de limão do mato.
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Highland, Garth. "Using functional boxplots to visualize reflectance data and distinguish between areas of native grasses and invasive old world bluestems in a Kansas tall grass prairie." Kansas State University, 2012. http://hdl.handle.net/2097/13806.
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Master of ScienceDepartment of Statistics
Leigh Murray
Using remotely sensed reflectance data is an appealing tool for controlling invasive species of grasses by rangeland managers. Recent developments in functional data analysis include the functional boxplot (FBP) which is shown here to be a useful tool in the visualization of reflectance data. Functional boxplots are a novel method of visually inspecting functional data and determining the presence of outliers in the data. Implementation and interpretation of FBPs are both straightforward and intuitive. The goal of this study is to examine the use of FBPs for visualizing reflectance data, and to determine the efficacy of using the FBP to distinguish between native tall grasses and invasive Old World Bluestem (OWB, Bothriochloa spp.) monocultures in a Kansas prairie. Validation trials were conducted in order to determine the stability of the FBP when used to analyze spectral data. FBPs were shown to be highly stable for use with both native and OWB grasses at all times and subsets of wavelengths tested. Identification trials were conducted by introducing a single OWB observation to a test set of native tall grass observations and constructing a FBP. Results indicate that using observations recorded early in the growing season, the functional boxplot is able to successfully identify the OWB observation as an outlier in a test set of native tall grass observations with an estimated probability 100% and 95.45% when considering the visible and cellular spectrums, respectively. A 95% lower bound for the probability of successfully identifying the OWB observation using the cellular spectrum in May is found to be 89.67%.
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Foster, Richard Douglas. "Fire, Soil, Native Species and Control of Phalaris arundinacea in a Wetland Recovery Project." [Johnson City, Tenn. : East Tennessee State University], 2003. http://etd-submit.etsu.edu/etd/theses/available/etd-0411103-140848/unrestricted/FosterR04162003f.pdf.
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Thesis (M.S.)--East Tennessee State University, 2003.Title from electronic submission form. ETSU ETD database URN: etd-0411103-140848. Includes bibliographical references. Also available via Internet at the UMI web site.
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McKay, Christina A. S. "And that one takes a big bite of one of those nice red apples, portraits of native women in Thomas King's Green grass, running water and Medicine river." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape15/PQDD_0012/MQ36501.pdf.
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Bertoncelli, Patricia. "Produção e germinação de sementes de Paspalum notatum : resposta à fertilização nitrogenada e manejo de cortes." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/180105.
Full textAbstract:
O presente trabalho foi desenvolvido na Estação Experimental do INIA La Estanzuela, em Colonia del Sacramento – Uruguai, de novembro de 2015 a março de 2017, com o objetivo de avaliar os parâmetros relacionados à produção e qualidade de sementes da espécie Paspalum notatum INIA Sepé. Buscou-se o entendimento dos componentes do rendimento de sementes frente a distintos níveis de fertilização nitrogenada e manejo de cortes. Foi utilizado o delineamento de blocos completamente casualizados com quatro repetições. Os tratamentos consistiram de quatro doses de fertilização nitrogenada (0, 75, 150 e 225 kg de N.ha-1) e três momentos de corte: corte precoce, corte tardio e sem corte, formando um arranjo fatorial 4x3. O padrão para realização do corte foi a fração da radiação fotossinteticamente ativa interceptada pelas plantas (50% para corte precoce e 80% para corte tardio). Para cada ano de estudo foram utilizados distintos locais dentro da mesma estação experimental a fim de avaliar a produção de sementes de plantas com idade similar (3 anos de idade), os quais foram denominados ambiente 2016 e ambiente 2017, sendo que no ambiente 2016 ocorreu maior deficiência hídrica no solo A aplicação de N possibilitou o incremento na massa de forragem, teor de proteína bruta, índice de nutrição nitrogenada e no número de perfilhos. A máxima produtividade de sementes alcançada situou-se próxima de 1000 kg.ha-1, rendimento atingido com 150 kg de N.ha-1 no ambiente 2016 e na dose 75 no ambiente 2017. Tal produtividade foi obtida com a realização de duas colheitas anuais, que foi possibilitada com a utilização de corte precoce e sem corte. Com o uso de corte tardio, por outro lado, foi possível a realização de apenas uma colheita anual, o que determinou menor rendimento total de sementes, porém possibilitou maior rendimento em apenas uma colheita. Com relação ao potencial germinativo das sementes, observamos que em situações de déficit hídrico, as plantas com suprimento de N comprometem a qualidade de sementes e favorecem o crescimento vegetativo, no caso de colheitas precoces. Por outro lado, a germinação foi melhorada quando aplicado nitrogênio associado ao corte tardio. Dessa forma, conclui-se que o ecótipo Paspalum notatum INIA Sepé possui bom rendimento de sementes, o qual é positivamente influenciado pela fertilização nitrogenada e aplicação de corte precoce.The present work was developed at the INIA La Estanzuela Experimental Station, in Colonia del Sacramento, Uruguay, from November 2015 to March 2017, with the objective of evaluating the parameters related to the production and quality of seeds of the specie Paspalum notatum INIA Sepé. We aimed understanding of the components of the seed yield under different levels of nitrogen fertilization and cutting management. A completely randomized block design with four replications was used. The treatments consisted of twelve factorial combinations of nitrogen fertilization doses (0, 75, 150 and 225 kg of N.ha-1) and three cutting times: early cut, late cut and no cut, totaling a factorial arrangement 4x3. The standard for cutting was the fraction of the photosynthetically active radiation intercepted by the plants (50% for early cutting and 80% for late cutting). For each year of study, different locations were used within the same experimental station in order to evaluate the seed production of plants with similar age (3 years old), which were named environment 2016 and environment 2017, wherein in the environment 2016 occurred greater soil water deficit The application of N promoted the increase in forage mass, crude protein content, nitrogen nutrition index and the number of tillers. The maximum seed yield reached was close to 1000 kg.ha-1, yield reached with 150 kg of N.ha-1 in the environment 2016 and at dose 75 in the environment 2017. Such productivity was obtained by performing two harvests annually, which was possible by the use of early cutting and uncut treatments. However, with late cutting was possible to perform only one annual harvest, which resulted in lower total seed yield, but with a higher yield in only one harvest. Regarding to the seed germination, we observed that in situations of water deficit, plants with N supply compromise their seed quality in detriment of vegetative growth in the case of early harvests. On the other hand, the germination was improved when N was associated with late cut. In this way, we concluded that Paspalum notatum INIA Sepé ecotype has a good seed yield, which is positively influenced by nitrogen fertilization and early cut application.
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Islam, Mohammed Anowarul. "Responses of accessions of Austrodanthonia spp. to factors associated with soil acidity." Thesis, The University of Sydney, 2002. http://hdl.handle.net/2123/502.
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Pasture plants already adapted to acidic soil conditions are required as part of an integrated approach (with lime amelioration) to managing acid soils on the Tablelands of New South Wales, Australia. The objective of this thesis is to evaluate the usefulness of Austrodanthonia species for this purpose. The material evaluated in this study was collected during a previous survey of the distribution of Austrodanthonia on the Central, Southern and Monaro Tablelands of New South Wales. It was hypothesised that the genus Austrodanthonia has a wide range of tolerance to acid soils. A series of experiments that provided information on the growth and physiology of Austrodanthonia in relation to soil acidity, with a view to the identification and eventual domestication of the most promising plant material have been conducted through pot, hydroponics and field investigations. Firstly, soils were acidified or limed to obtain a range of soil pH and Al concentrations. This experiment showed that adding aluminium sulfate and calcium carbonate followed by washing excess salts with water is a simple, rapid and convenient method for adjusting soil pH for pot experiments. The pH of the amended soils remained relatively unchanged eight months after treatment. The experimental set-up also resulted in a wide range of soluble Al (2-52 mg/kg) across the soils. The relative Al-tolerance of 183 accessions from 15 Austrodanthonia species was tested in a pot experiment using a range of soil pH. Emergence, survival and growth of all accessions were drastically reduced by high soil acidity (pH 3.9, P < 0.001). About 11% of plants emerged at pH 3.9, whereas at pH 4.4 and 5.3, ~72% of plants emerged. Accessions exhibited large variation within and between species in their tolerance to soil acidity. From the species/accessions tested, 49 accessions from eight species were selected for further study (on the basis of being more acid tolerant). Hydroponic experiments conducted in the glasshouse evaluated: (i) formulation of nutrient solution with a stable pH, (ii) effectiveness of the formulation using tap water and deionised water and (iii) estimation of free ion activities of Al and Mn in the nutrient solution and their effects on Austrodanthonia growth. These experiments showed that a NO3-N/NH4-N ratio of 9:4 is the most appropriate ratio to obtain a stable pH 4.0 without affecting plant growth; that there was little difference between tap water and deionised water on the ionic effects of Al and Mn, and plant-size did not play a role on accession survival and that accessions of Austrodanthonia could grow well within a wide range of pH (3.5-5.5), Al (50-250 �M) and Mn (100-2000 �M). Growth of Austrodanthonia accessions declined under high acidity (pH < 3.5) and Al (300 �M), but tolerated high concentrations of Mn (2000 �M). Root-tips stained with hematoxylin grouped accessions in a similar way to the pot and hydroponic experiments for most of the accessions tested. The intensity of root staining with hematoxylin and the differential distribution of Al in the shoots and roots provided an indication that different tolerance mechanisms may be involved with Austrodanthonia accessions. It appears that both exclusion and internal mechanisms may operate for Al- and Mn-tolerance. A field experiment was conducted at Carcoar (33037�S, 149013�E, elevation 800 m) using gradients in soil pH and Al available on-site to grow selected accessions of Austrodanthonia. The accessions exhibited a range of responses to soil acidity. The accession responses to acidity from the pot and hydroponic experiments were similar to those obtained in the field, especially where Al was present as a low Al-challenge. Overall, this study shows that Austrodanthonia exhibits a wide range of acid tolerance between species and accessions within species. Among the species tested, A. duttoniana and A. fulva appeared to have the greatest commercial potential, because of their productivity and acid tolerance. The variability that exists in the accessions may be exploitable in breeding and selection programs for improved cultivars.
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Islam, Mohammed Anowarul. "Responses of accessions of Austrodanthonia spp. to factors associated with soil acidity." University of Sydney. Food and Natural Resources, 2002. http://hdl.handle.net/2123/502.
Full textAbstract:
Pasture plants already adapted to acidic soil conditions are required as part of an integrated approach (with lime amelioration) to managing acid soils on the Tablelands of New South Wales, Australia. The objective of this thesis is to evaluate the usefulness of Austrodanthonia species for this purpose. The material evaluated in this study was collected during a previous survey of the distribution of Austrodanthonia on the Central, Southern and Monaro Tablelands of New South Wales. It was hypothesised that the genus Austrodanthonia has a wide range of tolerance to acid soils. A series of experiments that provided information on the growth and physiology of Austrodanthonia in relation to soil acidity, with a view to the identification and eventual domestication of the most promising plant material have been conducted through pot, hydroponics and field investigations. Firstly, soils were acidified or limed to obtain a range of soil pH and Al concentrations. This experiment showed that adding aluminium sulfate and calcium carbonate followed by washing excess salts with water is a simple, rapid and convenient method for adjusting soil pH for pot experiments. The pH of the amended soils remained relatively unchanged eight months after treatment. The experimental set-up also resulted in a wide range of soluble Al (2-52 mg/kg) across the soils. The relative Al-tolerance of 183 accessions from 15 Austrodanthonia species was tested in a pot experiment using a range of soil pH. Emergence, survival and growth of all accessions were drastically reduced by high soil acidity (pH 3.9, P < 0.001). About 11% of plants emerged at pH 3.9, whereas at pH 4.4 and 5.3, ~72% of plants emerged. Accessions exhibited large variation within and between species in their tolerance to soil acidity. From the species/accessions tested, 49 accessions from eight species were selected for further study (on the basis of being more acid tolerant). Hydroponic experiments conducted in the glasshouse evaluated: (i) formulation of nutrient solution with a stable pH, (ii) effectiveness of the formulation using tap water and deionised water and (iii) estimation of free ion activities of Al and Mn in the nutrient solution and their effects on Austrodanthonia growth. These experiments showed that a NO3-N/NH4-N ratio of 9:4 is the most appropriate ratio to obtain a stable pH 4.0 without affecting plant growth; that there was little difference between tap water and deionised water on the ionic effects of Al and Mn, and plant-size did not play a role on accession survival and that accessions of Austrodanthonia could grow well within a wide range of pH (3.5-5.5), Al (50-250 �M) and Mn (100-2000 �M). Growth of Austrodanthonia accessions declined under high acidity (pH < 3.5) and Al (300 �M), but tolerated high concentrations of Mn (2000 �M). Root-tips stained with hematoxylin grouped accessions in a similar way to the pot and hydroponic experiments for most of the accessions tested. The intensity of root staining with hematoxylin and the differential distribution of Al in the shoots and roots provided an indication that different tolerance mechanisms may be involved with Austrodanthonia accessions. It appears that both exclusion and internal mechanisms may operate for Al- and Mn-tolerance. A field experiment was conducted at Carcoar (33037�S, 149013�E, elevation 800 m) using gradients in soil pH and Al available on-site to grow selected accessions of Austrodanthonia. The accessions exhibited a range of responses to soil acidity. The accession responses to acidity from the pot and hydroponic experiments were similar to those obtained in the field, especially where Al was present as a low Al-challenge. Overall, this study shows that Austrodanthonia exhibits a wide range of acid tolerance between species and accessions within species. Among the species tested, A. duttoniana and A. fulva appeared to have the greatest commercial potential, because of their productivity and acid tolerance. The variability that exists in the accessions may be exploitable in breeding and selection programs for improved cultivars.
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Lopes, Vicente Guilherme. "QUANTIFICAÇÃO DAS RAÍZES FINAS EM UM POVOAMENTO DE Pinus taeda L., NA REGIÃO DOS CAMPOS DE CIMA DA SERRA, RS." Universidade Federal de Santa Maria, 2009. http://repositorio.ufsm.br/handle/1/8641.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThis study was conducted at Campos de Cima da Serra physiographic region, Cambará do Sul, RS, Brazil. The objectives of these study were: to comparatively quantify, the length and the biomass of fine roots (≤ 2,0 mm) inside the soil and in the litter and relate comparatively, soil chemical and physical variables in a Pinus taeda L., with 15 years of age, stand, implanted in a 3 x 2 m spacing, in 1993 and in a native grass area close to it. Samples were obtained through the use of monoliths methods described by Böhm (1979), based on the digging 3 monoliths (25 cm x 25 cm x 40 cm each), distributed inside the stand and 3 in native grass area. Roots were separated from the soil through washing and catching; after they were distributed over a white sheet of paper, where with a digital camera supported by a support with fixed height, 2.045 images were obtained. With the aid of the software, the images were processed to quantify roots length. After this procedure, the roots were dried in an oven and then weighed for biomass determination. Fine roots total length in Pinus stand, in 40 cm soil profile, including litter layer, was 68413 km ha-1, where the most part of them was concentrated in the first 20 cm and in the litter. In native grass area, the total length in 40 cm soil profile, was 173550 km ha-1, 42,82% (74313 km ha-1) of the total length is concentrated in the layer 0 10 cm. The roots density in native grass is 234, 28% higher than in Pinus. In Pinus until 40 cm depth, 3,52 Mg ha-1 was counted for fine roots biomass. Native grass showed 5,628 Mg ha-1, almost twice of fine roots biomass in Pinus. In both areas, soil chemical conditions, showed correlation with roots length and biomass. In Pinus, the main factors were P>K>V>Mg>Ca, on the other hand, in native grass area, the main factors were P>K>Ca>Mg>V. The great presence of fine roots in Pinus litter is important for cycling process, nutrients and water availability. After forest harvesting, litter and residues layer should remain, aiming the maintenance of soil productive potential.
O presente estudo foi realizado no município de Cambará do Sul, RS, Brasil. Os objetivos do trabalho foram: quantificar comparativamente, o comprimento e a biomassa de raízes finas (≤ 2,0 mm) no solo e na serapilheira e relacionar comparativamente, variáveis químicas e físicas do solo em um povoamento de Pinus taeda L., com 15 anos de idade, e uma área de campo adjacente. A obtenção das amostras foi realizada através do método de monolitos descrito por Böhm (1979), a partir da escavação de 3 monolitos de 25 cm x 25 cm x 40 cm em cada área. As raízes foram separadas do solo através de lavagem e catação e, na seqüência, foram distribuídas sobre uma folha de papel branca, onde com o auxílio de uma câmera digital, apoiada em um suporte de altura fixa, obtiveram-se 2.045 imagens digitais. Com o auxilio de um software, as imagens foram processadas para quantificação do comprimento das raízes. Após, as raízes foram secas em estufa e, depois, pesadas para determinação da biomassa. O comprimento total de raízes finas no Pinus, no perfil de 40 cm do solo, incluindo-se a camada de serapilheira, foi de 68412 km ha-1, sendo que, a maior parte dessas se concentrou nos primeiros 20 cm de profundidade e na serapilheira. Na área de campo, o comprimento total de raízes finas, no perfil de 40 cm do solo, foi de 173550 km ha-1, 42,82% (74313 km ha-1) desse comprimento localiza-se na camada de 0 - 10 cm de profundidade. A densidade de raízes no campo é 234,28% maior do que no Pinus, destacando-se a camada de 0 - 10 cm, onde ocorreu a maior diferença. No Pinus até a profundidade de 40 cm, foram contabilizados 3,52 Mg ha-1 para biomassa de raízes finas. A área de campo apresentou 5,63 Mg ha-1, ou seja, praticamente o dobro da biomassa de raízes finas presente no Pinus. Nas duas áreas, as condições químicas do solo apresentaram maior correlação com o comportamento do comprimento e biomassa de raízes. No Pinus, destaca-se como principais fatores o P>K>V>Mg>Ca, por outro lado, na área de campo, destacam-se P>K>Ca>Mg>V. A grande presença de raízes finas na serapilheira do Pinus destaca a importância desta camada no processo de ciclagem, disponibilização de nutrientes e água. Após a colheita florestal, deve-se manter a camada de serapilheira e dos resíduos produzidos durante essa atividade, visando à manutenção do potencial produtivo do solo.
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Cai, Qinyin. "Characterization of the genome in Timothy (Phleum pratense L.) : polyploid nature, phylogenetic relationships, and protein variation." Thesis, McGill University, 1991. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=70322.
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The genome constitution and phylogeny of hexaploid timothy (Phleum pratense L., 2n = 42) have been studied with C-banding and genome-specific DNA techniques. The cultivated species and two diploid wild relatives P. alpinum (2n = 14) and P. bertolonii (2n = 14) were karyotyped. In P. pratense, two sets of seven chromosomes could not be distinguished from each other either in gross morphology or in C-banding patterns and the third set was found to be differentiated from them. Two genomes, A and B, were established in this species presumably with the genome formula of AAAABB. The banded karyotype in P. alpinum was close to the A genome and that of P. bertolonii was analogous to the B genome, which suggests these wild species were the genome donors of P. pratense. To reinforce this, a molecular assay was performed with genome-specific probes. Eight clones specific to the genome of P. alpinum and thirteen specific to the genome of P. bertolonii were respectively isolated from the genomic DNA libraries of P. alpinum and P. bertolonii. Three P. alpinum-specific sequences and three P. bertolonii-specific sequences were used as probes to hybridize the DNA of P. pratense on slot blot and Southern blot. All the three P. bertolonii-specific probes and two of the three P. alpinum specific probes exhibited cross-hybridization to P. pratense DNA. This has confirmed the allopolyploid origin of hexaploid P. pratense. In addition, phenotypic variations of seed storage proteins were investigated within the cultivated P. pratense with SDS-PAGE analysis. A total of 44 protein monomers were detected in mature seed extracts from 19 cultivars of timothy. The protein banding patterns were differentiated among all the examined cultivars except for two pairs. Such differentiation makes it possible to identify the timothy cultivars.
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McCormick, S. "The nature and causes of spatial variability in forage grass production in cool temperate climes." Thesis, Queen's University Belfast, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419366.
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Boulanger, Kevin. "REAL-TIME REALISTIC RENDERING OF NATURE SCENES WITH DYNAMIC LIGHTING." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4284.
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Rendering of natural scenes has interested the scientific community for a long time due to its numerous applications. The targeted goal is to create images that are similar to what a viewer can see in real life with his/her eyes. The main obstacle is complexity: nature scenes from real life contain a huge number of small details that are hard to model, take a lot of time to render and require a huge amount of memory unavailable in current computers. This complexity mainly comes from geometry and lighting. The goal of our research is to overcome this complexity and to achieve real-time rendering of nature scenes while providing visually convincing dynamic global illumination. Our work focuses on grass and trees as they are commonly visible in everyday life. We handle geometry and lighting complexities for grass to render millions of grass blades interactively with dynamic lighting. As for lighting complexity, we address real-time rendering of trees by proposing a lighting model that handles indirect lighting. Our work makes extensive use of the current generation of Graphics Processing Units (GPUs) to meet the real-time requirement and to leave the CPU free to carry out other tasks.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Computer Science PhD
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Wendel, Paul J. "Creationism at the Grass Roots: A Study of a Local Creationist Institution." Kent State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=kent1207843937.
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Veldsman, Stephan Gerhardus. "Vegetation degradation gradients and ecological index of key grass species in the south-eastern Kalahari South Africa." Diss., Pretoria : [s.n.], 2009. http://upetd.up.ac.za/thesis/available/etd-08112009-165447.
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Blazejewski, L. "Keep off the grass! : an exploration of how photographic practice may be used to develop alternative representations of the urban nature subject." Thesis, University of Salford, 2013. http://usir.salford.ac.uk/29575/.
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The relationship between people and nature has long been suffering from a cultural disconnect. In truth, nature is far more readily likened to travel than it is to everyday life; synonymous, as it is, with those faraway ideals beyond the everyday reach of an urban dweller. However, urban environments are teeming with a range of plants and animals, known as urban nature, thus providing the opportunity to shed these exotic associations in favour of a far more accessible experience. In order to do so, the form of contemporary urban nature photography will be examined in this thesis, where any representational trends found to be inhibiting its development will be identified, and ultimately challenged. A combination of photographic practice and reflective analysis was used to challenge these problematic trends. Five experiments were carried out. These served to yield a set of photographs which developed alternative representations of the urban nature subject. The resulting photographs of each experiment were subjected to a means of reflection; based on Gary Rolfe’s three stage method but refocused for compatibility with photographic practice, where observations were drawn from one experiment so as to guide the direction of the following experiment. These experiments culminated in a final project: a definitive body of photographs that served to fuse the findings of each experiment into an alternative aesthetic. Identity became a critical theme underlining the representations of the urban nature subject in this thesis, for the displacement of photographic information began to instil the subject with - to some extent - otherworldly sensibilities. This process challenged the active predisposition toward naturalism in urban nature photography, and began to direct such tendencies toward a much broader aesthetic landscape; engaging with unreserved artistic ideologies so as to develop exclusive representations of the urban nature subject.
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Nacir, Houda. "Nature et origine des lipides des plastoglobules." Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0080/document.
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Les plastoglobules sont de petites particules localisées au niveau des plastes qui stockent des lipides neutres tels que les triacylglycérols (TAG), du tocophérol et des caroténoïdes. Leurs nombre et diamètre changent en fonction de l’espèce de plante, du type de plaste, du stade de développement et des conditions environnementales. Dans les chloroplastes, les plastoglobules sont liés physiquement aux thylacoïdes par une monocouche de lipides polaires en continuité avec le feuillet externe des thylacoïdes. Ceci suggère qu’il y a une dynamique d’échange de métabolites tels que les lipides entre les deux compartiments. Cependant, la composition lipidique des plastoglobules est mal décrite. L’objectif de ce travail a été d’établir la nature exacte des lipides des plastoglobules en condition de culture standard par TLC/GC-FID suivie d’une étude par LC-MS/MS. Ces travaux ont montré que les plastoglobules sont composés majoritairement d’acides gras libres et de phytyls esters. En plus des lipides neutres, ils sont composés de galactolipides, de la PC et du PG de composition spécifique, riche en acides gras saturés, différente de celle des thylacoïdes et de l’enveloppe. Le deuxième objectif a été de définir l’origine des lipides des plastoglobules par l’étude de la cinétique de marquage des lipides en condition de stress. Ainsi, pendant le stress, une partie des acides gras issus de la dégradation des galactolipides des thylacoïdes sera à l’origine de la formation des phytyl esters puis stockée dans les plastoglobules. En conclusion, ces résultats suggèrent la présence de micro-domaines au niveau des thylacoïdes qui favoriseraient la formation des plastoglobulesPlastoglobules are small lipoprotein particles localized inside plastids. They are surrounded by a monolayer of polar lipids, proteins and they store neutral lipids such as triacylglycerol, carotenoids and tocopherol. During plastid development or in response to stress conditions, plastoglobules increase in number and size along with thylakoids disintegration, and reciprocally, their number and size decrease while thylakoids are developing. Plastoglobules are surrounded by a leaflet contiguous with the thylakoid outer leaflet and therefore share a physical link with thylakoids. This connection suggests exchange of molecules between these two compartments. The protein composition of plastoglobules is well known. However, the lipid composition of plastoglobules is still unknown. Thereby, the aim of our study is, at first, to establish the nature and the origin of plastoglobules from Arabidopsis and pea leaves. Using TLC/GC-FID analysis and by LC-MS/MS we identified nature of the lipids composing the plastoglobules. Moreover, doing pulse and chase analysis during stress condition, we obtained information about the origin of plastoglobules lipids. Our results show that plastoglobules are composed in majority from neutral lipids, principally free fatty acids and phytyl esters. Moreover, plastoglobules contain polar lipids such as galactolipids and phospholipids (PC and PG) have a specific lipid composition different from the thylakoid leaflet and envelope. In addition, during stress conditions plastoglobules store phytyl esters coming from fatty acids of galactolipides in degradation. To summarize, the specific composition of plastoglobules suggest that microdomains might exist in thylakoids that would favor plastoglobule formation
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Eljammal, Tamim. "Nature et distribution des hydrocarbures et des acides gras dans des sédiments marins oxydes et réduits." Aix-Marseille 3, 1989. http://www.theses.fr/1989AIX30034.
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Prévéraud, Damien P. "Effet de la nature des acides gras des triglycérides alimentaires sur la biodisponibilité de la vitamine E chez le porc." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM5079.
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Un premier travail basé sur une méta-analyse de la littérature a permis de révéler le rôle positif des acides gras saturés (AGS) et monoinsaturés (AGMI) sur les concentrations tissulaires en α-tocophérol. Les acides gras polyinsaturés de la famille des oméga-3 (AGPI n-3) auraient, quant à eux, un effet délétère sur les concentrations d'α-tocophérol dans les tissus. Cette observation a été globalement confirmée lors d'un essai in vivo réalisé sur des porcelets en croissance supplémentés avec différentes sources de matière grasse. La concordance des résultats de la méta-analyse avec ceux de l'essai porc nous a permis d'élaborer plusieurs hypothèses de travail dont la première visait à mettre en évidence l'importance de l'étape d'absorption de la vitamine E et l'effet possible des acides gras à ce niveau. Ce test exploratoire réalisé sur volaille (choisi pour son absence de transport lymphatique de la vitamine E, notamment) n'a pas confirmé les résultats obtenus sur le modèle porcin, probablement dû au métabolisme particulier de la vitamine E entre ces deux espèces. Parallèlement à cela, une série de tests in vitro a montré que les mécanismes explicatifs passent, au moins en partie, par un effet sur la micellarisation et l'hydrolyse de l'acétate de tocophérol dans la lumière intestinale. Néanmoins, d'autres mécanismes sont probablement impliqués, comme un effet des AGMI sur la sécrétion entérocytaire des chylomicrons, ou encore un effet pro-oxydant des AGPI dans les tissus qui entraînerait une utilisation de la vitamine E tissulaireA preliminary meta-analysis of data obtained from published trials on this topic concluded that dietary saturated (SFA) and monounsaturated (MUFA) fatty acids seemed to have a positive effect on tissue α-tocopherol concentration. Conversely, dietary polyunsaturated fatty acids (PUFA), especially those belonging to the n-3 family, led to a lower vitamin E concentration in tissues. An in vivo trial was run to study these observations, with growing pigs fed diets supplemented with different fat sources. The results of the trial confirmed the conclusions obtained from the meta-analysis of data from the previously published studies. Our consistent results obtained by two approaches (meta-analysis and pig trial) allowed us to formulate several research hypotheses. An additional trial was then performed to study the possible effect of dietary fatty acids, specifically on the absorption step. This exploratory study was carried on poultry (an interesting model that does not exhibit any vitamin E lymphatic transport system) but did not confirm the results obtained in the swine model, showing a specific metabolism of vitamin E within the two species. A series of in vitro experiments indicated that the mechanisms involved occurred, at least for a part, during the solubilization into micelles and the hydrolysis of the tocopheryl acetate form in the intestinal tract. Nevertheless, other mechanisms could be involved, like the effect of MUFA on chylomicron release by the enterocyte, or the pro-oxidant effect of PUFA increasing the vitamin E utilization in tissues as well
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Vallot, Agnès. "Etude de la répartition chyloportale des acides gras chez le rat : influence de la quantité d'acide gras et de la nature de l'émulsion lipidique infusée : application aux acides caprique, palmitique, oléique et linoléique." Dijon, 1986. http://www.theses.fr/1986DIJOS053.
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Mise en évidence de l'influence de la longueur et du degré d'insaturation de la chaine carsonée sur l'absorption par voie sanguine des acides gras. Recherche d'une possible influence des autres composants de l'alimentation sur la répartition chyloportale.
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Vallot, Agnès. "Etude de la répartition chyloportale des acides gras chez le Rat influence de la quantité d'acide gras et de la nature de l'émulsion lipidique infusée, application aux acides caprique, palmitique, oléique et linoléique /." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb376016902.
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Idrissi, Taghki Abdelghani. "Etude du type métabolisme intégré entre embryons de colza natif et transgénique : analyse et compréhension de la modification induites dans les lignées transgéniques de colza et de lin : analyse enzymatique et métabolique." Compiègne, 2009. http://www.theses.fr/2009COMP1798.
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Le développement des connaissances sur le métabolisme lipidique, des techniques de génie génétique ainsi que l'identification et l'isolement de nombreux gènes intervenant dans la biosynthèse et la régulation du métabolisme des lipides dans les plantes, ont offert de nouvelles perspectives pour la production d'huile végétale à plus haute valeur ajoutée, dans des plantes de grande culture. Dans cette perspective, les projets REFLAX et PAGIOS ont été élaborés. L'objectif de ces projets est la production d'acides gras inhabituels dans des plantes agronomiques, colza et lin, par la création d'une nouvelle voie de biosynthèse d'acides gras branchés dans les plastes de ces plantes. A cet effet des plantes de colza ont été transformées avec quatre enzymes bactériennes : TD, KS, PCCA et PCCB, identifiées comme enzymes clés dans la synthèse d'acides gras branchés. L'accumulation des acides gras méthylés, suite à l'introduction des ces enzymes dans les plantes de colza transformées, reste très faible (< 2%). Afin de mieux comprendre cette faible production d'AGB, des embryons de colza, à différents stades de développement, ont été incubé en présence de "C-glucose. Les analyses RMN et biochimiques ont démontré que la synthèse d'AGB été très faible et transitoire, que des flux de synthèse des produits de réserves été similaire entre colza natif et transformé et que le métabolisme carboné central n'été pas affecté par l'introduction de ces gènes. Il a été également observé, au cours de ces analyses, une accumulation de pyruvate et de kétobuiyrate ainsi qu'une faible accumulation d'acides aminés branchésThe importance of these unusual structures for fatty acids, the development of genetic engineering and the identification and isolation of many genes involved in the biosynthesis and regulation of lipid metabolism in plants, have provided new perspectives for the production of vegetable oil with a higher value in field crops. In this perspective, REFLAX and PAGIOS programmes were developed. The aim of these projects is the production of unusual fatty acids in agronomie plants (rapeseed and flan), through the creation of a new ,biosthetic pathway for branched fatty acids in the plast. Rapeseed plants were transformed with four bacterial enzymes: TD, KS, PCCA and PCCB. These proteins were identified as key enzymes in the synthesis of branched fatty acids. The level of methylmalonyl-CoA, a precursor of the methyl branched fatty acid synthesis, was amplified thanks to the introduction of these four genes. However the accumulation of methyl branched-chain fatty acids in rapeseed plants transformed, remains very low (<2%). To get a deeper understanding of this low production of BFA, we incubated whole rapeseed embryos, at different stages of development, in presence of 13C-labelled glucose and observed the label redistribution by NMR. The NMR and biochemical analysis showed that the synthesis of BFA was very low and transient (only at 15 J). Biomass synthesis fluxes were similar between native and transformed plant. The central carbon metabolism was not affected by the introduction of these genes. However, an accumulation of' pyruvate and kétobutyrate and a low accumulation of branched Chain amino acids (leucine, isoleucine and valine) at the transformed lines were observed
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Adarkwa, Muriel Animwaa. "The countercyclical nature of remittances: A case study of the 2009 global financial crisis in Cameroon, Cape Verde, Nigeria and Senegal." University of the Western Cape, 2017. http://hdl.handle.net/11394/5681.
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Magister Artium (Development Studies) - MA(DVS)Remittances inflows have gradually become one of the major sources of external financial inflows to developing countries. As a result, research abounds on the developmental effects of remittances in the home countries of migrants. At the micro level, recipients of remittances are more likely to have better access to quality health care, education as well as start-up fund for their own businesses. On the other hand at the macro level, remittances inflows can help increase the credit worthiness of countries by enabling them to use future remittances inflows as collateral for loans. Additionally, remittances inflows as a source of foreign exchange can be used by countries to fund import bills. Although there has been a surge of scholarship on remittances, this scholarship seems to be concentrated on the economic study of migration instead of the macroeconomic aspects of remittances. Furthermore, comparative studies on these macroeconomic aspects of remittances especially on African countries are underresearched and remains at the backwaters of academic study. Using quantitative time series data, this research seeks to do a comparative study on the countercyclical nature of remittances in four selected West African countries (Cameroon, Cape Verde, Nigeria and Senegal). The research used descriptive trend analysis, autocorrelation and an ARMAX model analyse the research problem. After critical analysis on whether remittances are countercyclical or not using the 2009 global financial crisis as a reference year in these four countries, it was found that, remittance inflows to Cameroon, Cape Verde, Nigeria and Senegal were pro-cyclical in nature. Moreover, in analysing the relationship between remittances inflows and gross domestic product (economic growth) the research revealed that there was a positive relationship between remittances inflows and economic growth for the four countries (Cameroon, Cape Verde, Nigeria and Senegal) observed. One recommendation given from this study is that, there is the need for remittances inflows to be invested in productive activities. This is because even if remittances continue to increase, without its investment in productive sectors, it cannot have any meaningful impact on economic growth in these countries.
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Villeneuve, Laure. "Influence nutritionnelle de la vitamine A et de la nature des lipides sur la morphogenèse de la larve de bar (Dicentrarchus Labrax) : implication de la voie des rétinoi͏̈des." Rennes 1, 2005. http://www.theses.fr/2005REN1S005.
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Le but de ce travail était de tester l'effet nutritionnel de la vitamine A et des AGPI (dont l'EPA et le DHA) sur le développement des larves de bar. Un excès de vitamine A dans l'aliment provoquait des malformations au niveau de la tête reliées à une hausse de la transcription de RAR? et la perte d'une vertèbre lorsque les larves étaient nourries avec cet aliment de J8 à J13. Un aliment contenant un excès d'AGPI perturbait le développement de la colonne vertébrale des bars, les malformations étaient corrélées à une chute de l'expression de RARa, RAR?, RXRa et BMP4 et une vertèbre surnuméraire apparaissait sur les larves nourries de J8 à J13 avec cet aliment. Un aliment contenant 31 mg/kg de matière sèche de vitamine A et entre 1. 1 et 2. 3% d'EPA + DHA permet un développement harmonieux des larves. Il apparaît que la période J8-J13 est cruciale pour le développement, période pendant laquelle les larves sont très sensibles à la nature et à la teneur des nutriments
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Cayouette, Murielle. "MOUTAINS AND RIVERS FOR A HOME. A Study of the Cultural and Social Repercussions of the Return to Nature in Leslie Marmon Silko’s « Ceremony » and Thomas King’s « Green Grass, Running Water »." Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/29760/29760.pdf.
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La présente recherche a pour but de procéder à une étude comparative du processus régénératif au cœur de deux romans phares de la fiction autochtone contemporaine, soit Ceremony de Leslie Marmon Silko et Green Grass, Running Water de Thomas King. Trois volets principaux sont examinés : le rôle de la nature en tant que référent culturel dans le processus de régénération des personnages principaux de chaque roman, l’évolution de la quête identitaire dans un environnement post-contact, ainsi que les répercussions de la réactualisation de l’identité de chaque protagoniste sur la communauté à laquelle il appartient. Cette comparaison entre les procédés employés par Silko et King permettront, en un premier temps, d’identifier des éléments de continuité entre les deux auteurs. Ces similarités incluent la centralité de la nature dans la reconnexion des protagonistes avec leur culture et leur identité ainsi que l’emphase sur la nécessité d’une identité hybride dans un environnement post-contact. De plus, la comparaison entre ces deux auteurs issus de deux contextes socio-historiques distincts permet d’isoler certains éléments du contexte propre à chaque roman afin de déterminer le rôle de la réalité autochtone sur la fiction produite à chaque époque. De façon plus spécifique, il sera entre autres question de l’influence de la montée du mouvement environnementaliste euro-américain sur la valeur symbolique du retour à la nature, ainsi que de l’importance grandissante de la classe moyenne autochtone éduquée et de la façon dont ce nouveau phénomène est exprimé dans l’œuvre de King.This thesis compares the regenerative processes at the heart of two milestone novels of contemporary Native American literature, Leslie Marmon Silko’s Ceremony and Thomas King’s Green Grass, Running Water. My comparative study will be divided into three main sections: the role of nature as a cultural referent in the main characters’ regenerative processes in each novel, the evolution of the identity quest in a post-contact environment, and finally, the repercussions of the protagonists’ re-actualization of identity on the rest of their community. Through the comparative study of the processes employed by Silko and King with respect to one’s relationship to nature, cultural identity and social relations, I will be able to identify several similarities shared by the two novels, which demonstrate that they belong to the same Native artistic continuum. These resemblances include the central role of nature in reconnecting the protagonists to their identity, as well as a predominant emphasis on the emergence of a hybridized identity in a post-contact environment. Moreover, the comparison of two novels emerging from two different eras of Native American Literature –that of the 1970s and of the 1990s- will allow me to isolate the influence of the cultural context to which each particular work belongs. In doing so, it becomes possible to determine the influence of some transformations in Native lifestyle on the fiction produced at a given time. More specifically, the modifications I chose to focus on include the rise of Euro-American environmentalism on the symbolic value of returning to nature for Natives as well as the increasing presence of middle-class, educated Natives and their representation, mostly present in King’s fiction.