Doctor of Philosophy / Department of Biology / Jack F. Cully, Jr. / Dispersal remains one of the most important, yet least understood, life history traits. As the vehicle of gene flow among populations, dispersal can both relieve inbreeding depression and prevent local adaptation. Regionally, dispersal can stabilize or destabilize metapopulations, given its critical roles in disease transmission among populations as well as recolonization following local extinction events. Furthermore, in light of climate change and increasing habitat loss and fragmentation, the ability to navigate through unfamiliar, unsuitable habitat between populations is essential to the long-term survival of a species across its range. In my dissertation, I present a multi-scale investigation of factors affecting gene flow and disease transmission among populations of a keystone species and an agricultural pest of the North American prairie: the black-tailed prairie dog (Cynomys ludovicianus). Black-tailed prairie dogs are social, ground-dwelling squirrels that live in spatially isolated populations called colonies. First, we conducted a landscape genetic analysis of black-tailed prairie dogs throughout a large portion of their current range. Our estimates of gene flow indicate that the genetic neighborhood size of both male and female prairie dogs reaches 40-60 km within short-grass prairie, whereas colonies within mixed-grass prairie are more isolated. At a broad scale, we observed isolation-by-distance among colonies and great influence of grassland productivity on genetic connectivity; however, neither distance nor landscape characteristics greatly explained observed genetic differentiation among colonies separated by < 50 km. Last, we investigated whether landscape features could predict disease transmission patterns of sylvatic plague among colonies in short-grass prairie and found evidence that pastures act as corridors for plague transmission. Our results indicate that black-tailed prairie dogs are more resilient to habitat loss and fragmentation than other obligate grassland species and likely capable of transmitting sylvatic plague over long distances. Taken together, these studies illustrate how a multi-scale approach can reveal complexities of dispersal dynamics that would otherwise remain undetected.

Master of Science / Department of Biology / David C. Hartnett / The effects of bison activities on forb diversity and cover have been well-established, but less is known about how forb life history is altered by bison-mediated habitat changes. This study had three main objectives: 1) to evaluate the hypothesis that release from aboveground competition with grasses may contribute to the increased cover and diversity of forbs in prairie grazed by bison relative to ungrazed prairie, 2) to determine whether differences in forb reproductive effort between grazed and ungrazed habitats were size-dependent, and 3) to look for evidence of a trade-off between allocation to vegetative and sexual reproduction. The growth, biomass allocation, and sexual reproduction of six common unpalatable perennial species were measured and compared between bison-grazed and ungrazed tallgrass prairie burned at 2-year intervals: Ambrosia psilostachya, Artemisia ludoviciana, Baptisia australis, Psoralidium tenuiflorum, Solidago canadensis, and Vernonia baldwinii. Vegetative reproduction was also measured for B. australis¸ S. canadensis, and V. baldwinii. Light availability, canopy density and height, and percent cover of neighboring plants were measured in each studied individual’s immediate neighborhood and compared between habitats to establish the possibility of differing aboveground competition. Aboveground competition may be lower in bison-grazed habitats, as evidenced by differences in habitat characteristics and plant performance found in this study. In bison-present habitats, sexual reproduction was elevated for all six species and average plant size was greater for all species except A. psilostachya. Vegetative reproduction was not clearly different between habitats for all three species examined. Sexual reproduction increased with size for all species, and the relationship differed significantly between habitats for all species except A. psilostachya. Allocation to vegetative reproduction was not generally related to aboveground biomass, nor was there a clear trade-off between allocation to vegetative and sexual reproduction. The results of this study provide evidence that release from aboveground competition with grasses promotes the growth and sexual reproduction of the studied species of forb, and that differences in sexual reproduction are not entirely size-dependent. Patterns in allocation to vegetative reproduction were less clear and were not clearly tied to sexual reproductive allocation.

Doctor of Philosophy / Department of Biology / Ari M. Jumpponen / Dark septate endophytes (DSE) are darkly pigmented microfungal ascomycetes commonly observed in the healthy plant roots. Studying the functional roles of DSE is challenging as fundamental information about their identity, nutritional requirements, host range or host preference are lacking. Objective 1: root colonizing fungi were isolated from Konza plants roots and DSE fungi were identified by testing Koch’s postulates using leek plants. Periconia macrospinosa and Microdochium sp., were identified as DSE as they produced microsclerotia and chlamydospores in the root cortex. Select DSE were tested for their enzymatic capabilities and ability to utilize nitrogen sources: fungi tested positive for amylase, cellulase, polyphenol oxidases and gelatinase. Periconia isolates utilized organic and inorganic nitrogen suggesting facultative biotrophic and saprotrophic habits. Objective 2: a Microdochium isolate and three Periconia isolates were screened on 16 plant species (six native grasses and forbs, four crops) in a resynthesis system to test host range. DSE colonized all plant species, albeit to varying degrees. Host biomass and nutritional levels to DSE colonization varied within and among host species confirming the broad host range. Based on % responsiveness to DSE colonization, a metric similar to ‘mycorrhizal dependency’, grasses responded positively, while forbs and crops responded negatively. To test this observed ‘host preference’ under natural conditions, Konza roots from seven grass and nine forb species were surveyed for DSE colonization. Grasses hosted 50% greater DSE than forbs, supporting the broad host range and host preference of DSE fungi. Objective 3: three conspecific Arabidopsis ecotypes, Col-0, Cvi-0 and Kin-1 were inoculated with 25 P. macrospinosa isolates in resynthesis system. The three ecotypes responded differently to inoculation: Col-0 and Cvi-0 responded negatively, while Kin-1 response was neutral. Despite the negative or neutral response, each ecotype responded positively to one or two isolates. The outcomes were along the mutualism-parasitism continuum precluding an unambiguous assignment to any particular life-style. This study shows that the outcomes along this continuum are dictated by host and fungal genotypes. However, the more important question about their function remains. Additional studies with Arabidopsis microarrays are likely to provide unique insights into the potential roles of DSE.

Master of Arts / Department of Geography / Kendra K. McLauchlan / The quantitative relationship between pollen assemblages in sediment and vegetation cover is largely unknown because many factors influence this relationship. This lack of quantitative relationship is particularly acute in grassland regions, where both past and future climate change have the potential to determine grassland composition and cover. The tool used to reconstruct past grassland cover is the relative abundance of distinct fossil pollen types preserved in sediment. However, the interpretation of grassland pollen assemblages as grassland vegetation types needs to be refined to improve these reconstructions. Using pollen found in the surface sediments from 24 artificially-constructed ponds in the Flint Hills ecoregion of Kansas, USA, I examined relationships between pollen and vegetation in the tallgrass prairie biome, which includes woody components. By comparing the pollen data to field-surveyed vegetation data and land cover classifications taken from Kansas Gap Analysis Program data, I correlated pollen and vegetation in this ecoregion. Pollen productivity estimates for Artemisia, Ambrosia, Asteraceae, Chenopodiaceae, Cornus, Fabaceae, Juniperus, Maclura, Poaceae, Populus, Quercus, and Salix were calculated via the Extended R-Value Model. Common pollen types identified in sediments are mostly herbaceous grassland plant species such as Poaceae, Artemisia, and Ambrosia, but woody plants such as Populus, Quercus, and Juniperus are also represented. PPEs have been calculated for four of these taxa in Europe, and values from the Flint Hills are higher. These are the first PPEs reported for eight of these taxa. This research will further advance quantitative vegetation reconstructions in the Great Plains of North America and refine interpretations of how climate change affects grasslands.

Ce travail propose d'analyser et de modéliser le fonctionnement biophysique et décisionnel d'un système prairial irrigué par gravité. Il est appliqué aux prairies plurispécifiques de Crau. Le système étudié est découpé en deux sous-systèmes : le sous-système biophysique sol-plante-lame d'eau et le sous-système technique, décrit par les processus décisionnels des agriculteurs. L'approche systémique, nous a conduits à décomposer le système biophysique en compartiments interagissant entre eux et passant par une succession d'états. Cette approche structure les expérimentations et la modélisation numérique. Nous montrons que la prairie plurispécifique est sensible en quantité et en qualité aux déficits hydrique courts et modérés et que l'irrigation peut être pilotée à partir du potentiel matriciel et de la fraction d'eau du sol transpirable par la culture. Les données expérimentales permettent d'améliorer et calibrer un modèle de lame d'eau basé sur une loi d'infiltration prédictive et un modèle de culture basé sur une approche des traits fonctionnels. La qualité de prédiction, obtenue par validation croisée, est satisfaisante par rapport à l'utilisation souhaitée du modèle, les effets du vent et de la plurispécificité sur le rendement ayant été intégrés. Un modèle conceptuel des décisions est construit à partir d'une enquête sur le fonctionnement du système de production en adaptant le concept de ‘modèle d'action' aux systèmes gravitaires et aux prairies. Le couplage de ces modèles complètera ce travail afin d'élaborer un outil d'aide à la conception de systèmes de culture plus efficients en termes d'usage de l'eau.

The Lewisville Lake Environmental Learning Area (LLELA) is a wildlife management area with tallgrass prairie, an endangered ecosystem. Essential ecosystem processes, especially fire, are part of restoration. To support fire management efforts at LLELA and surrounding areas, this project evaluated and developed tools for fire restoration. The four primary prairie grasses respond favorably to burning. Fuel loads and fuel models vary by scale and survey method. One- and 10-hour fuel moisture can be predicted using a statistical model; 100- and 1,000-hour fuel moisture cannot. Historic weather data suggests that burning can occur when it is most effective. The production of ozone precursors produced by burning is comparable to those emitted every six minutes by regional automobiles.

Area sensitivity of North American grassland birds is a significant conservation concern; yet, its causes are not known. I used point count data from 20 tall-grass prairie patches in Southern Manitoba to assess the relative importance of patch size, edge proximity, and landscape composition on the densities and species richness of grassland songbirds. The degree to which the landscape surrounding point count plots was open, as opposed to forested or urban, had a positive effect on species richness and the densities of most focal species, and was more important than patch size, edge proximity, or habitat amount. These results suggest that landscape openness, not patch size (with which it is usually correlated) drives area sensitivity. Small grassland patches embedded in open landscapes are less susceptible to area sensitivity and may be of high conservation value for grassland birds. / February 2017

Les prairies assurent différents services auprès de l’agriculture et de la société, dont les plus fondamentaux sont de produire le lait et la viande que nous consommons, mais également d’atténuer les émissions de gaz à effet de serre (GES) en piégeant une partie du carbone atmosphérique dans leurs sols. L’anticipation des risques associés à la continuité de ces services, dans le contexte de changement climatique (CC) et démographique futur, est l’un des enjeux agricole et sociétal de demain. Dans ce cadre, cette thèse vise à i) modéliser les impacts du CC sur les services et le bilan de GES des prairies, en tenant compte de la variabilité climatique accrue prédite par les modèles climatiques, mais également ii) à fournir des pistes d’adaptations du système fourrager dans le cas de systèmes d’élevage bovin herbagers. Pour cela, nous avons développé les modules animal et végétal de PaSim afin, d’une part, de représenter de façon mécaniste les performances animales et les émissions de méthane entérique au pâturage et, d’autre part, de rendre compte des interactions de la diversité végétale avec le CC et la gestion des prairies. PaSim a ensuite été utilisé pour simuler, en 12 sites français, les impacts du CC sur des prairies mono ou plurispécifiques, dans différentes conditions pédoclimatiques et de gestion. Le modèle a été forcé par des scénarios climatiques à haute résolution couvrant la période 1950-2100 et issus de différents scénarios socio-économiques, modèles climatiques et méthodes de régionalisation / initialisation. Les conséquences du CC sont globalement assez favorables, hormis pour la production fourragère estivale et la restitution d’eaux aux nappes, pour lesquels les risques d’une diminution significative sont accrus. Les sites plus arides ne sont pas nécessairement ceux qui connaîtront la plus forte évolution négative, même si, en absolu, ils restent ceux présentant les déficits fourragers et hydriques les plus forts. De nouvelles opportunités pour la production fourragère s’offre aux saisons autres que l’été, laissant présager de changements saisonniers importants qui nécessiteront fatalement une adaptation des systèmes d’élevage de ruminants. Une étude de cas, centrée sur les bassins de production breton et du Massif Central, a permis de montrer que ces changements pourraient s’accompagner de modifications de la distribution de fourrages et de concentré en complément de l’herbe pâturée, avec parfois, une exclusion des troupeaux de la pâture l’été. Des systèmes fourragers offrant une certaine flexibilité face à l’aléa climatique pourraient permettre d’exploiter à son maximum l’herbe pâturée, avec des temps de pâturage plus longs et davantage de surfaces allouées au pâturage, et par conséquent des chargements plus élevés. Ces adaptations ne devraient pas nuire au bilan net de GES à l’échelle du système, exprimé par UGB jour. En revanche, afin de soutenir le potentiel de production, elles pourraient nécessiter un recours plus important à l’azote et, de fait, augmenter les pollutions azotées à l’échelle du système. / Grasslands ensure a variety of services to the agricultural community and the society as a whole. Dairy and beef production are the major objectives of grassland management. However, they are also effective to mitigate greenhouse gas (GHG) emissions by sequestering the atmospheric carbon into the soil. Considering the challenges of demographic and climate changes (CC), anticipating the risks associated to the continuity of these services is to date a major societal concern (and is likely to remain a topic of public concern in the foreseeable future). In this context, the thesis aimed at: i) modelling the impacts of CC on grassland services (including the GHG budget), while accounting for the increased variability of future climate as projected by climate models ; ii) identifying pathways to CC adaptation of pasturebased livestock systems. By considering such goals, novel animal and plant modules were developed for the Pasture Simulation model (PaSim) that allowed, on the one hand, a mechanistic representation of the animal performance and methane emissions at pasture and, on the other hand, assessing interactions between vegetation diversity, CC and pasture management. PaSim has been used to simulate the impacts of CC on monocultures and multispecies grasslands run at 12 French sites across a range of soil, climate and management conditions. The model has been forced by high-resolution climate projections over 1950-2100, as generated by a set of socio-economic scenarios, climate models, and regionalization / initialization methods. Overall, the projected consequences of CC on French grasslands are not severe. Major concerns refer to summer forage deficit and water table depletion, for which significant risks of reduction may arise. If the most arid sites will not necessarily experience the worst CC impacts, they remain affected by the most critical conditions of forage and water deficit. Some opportunities for forage production that may arise for other seasons than summer involve important seasonal changes, which may also require the adaptation of pasture-based livestock production systems. A case study on two major production districts – Brittany and Massif Central – showed that CC will affect accompanied by the need of modifying forage and concentrate distribution to complement the grazed pastures. Moreover summer grazing will not be possible in some years. Flexible systems will allow better exploiting grazed grasslands. This may be achieved by extending the grazing periods and increasing the area allocated to pasture, while also increasing the animal density. Such adaptation measures proved not to worsen the GHG budget of the system, per livestock unit day. In contrast, increased supplies of nitrogen fertilizers to match the increased productivity potential may increase nitrate leaching.

Doctor of Philosophy / Department of Agronomy / Ganga M. Hettiarachchi / Although phosphorus (P) is an essential nutrient for the growth of plants, it is one of the most limiting nutrients in terms of availability as a high proportion of applied P rapidly transforms into insoluble forms with low solubility in soils. To further understand the fate of P applied to soils, two separate but related studies using three high P-fixing soil types each were used for which the objectives were to investigate the mobility, availability, and reaction products from two granular and one liquid P fertilizer alone or plus a fertilizer enhancement product. Energy dispersive spectroscopy showed a substantial amount of P remained in the granule following a 5-week incubation. At the end of the 35-day incubation period there was evidence that the fluid fertilizer was superior over the granular sources in terms of enhanced diffusion and extractability of P for three calcareous soils with varying levels of CaCO3. Phosphorus x-ray absorption near-edge structure (XANES) spectroscopy results in conjunction with resin-extractable P indicated a strong negative correlation between Ca-P solids formed and P extractability, suggesting that degree of Ca-P formation limits P solubility. For the three acidic P-fixing soils the results were complex. In two out of three acid soils, liquid P treatments diffused farther from the application point than the granular treatments. Phosphorus XANES results suggested that Fe-P or Al-P interactions control the overall P solubility. Integration of pH, resin extractable-P and XANES results suggested the P retention mechanism was either dominated by adsorption or precipitation depending on soil pH. More acidic soil conditions favored precipitation. The objectives of the third study were to observe how long-term (14 years) addition of P with or without N influences the inorganic and organic P pools in a native grassland soil using sequential fractionation, XANES, and 31P-nuclear magnetic resonance (NMR) spectroscopy. The overall results suggested that P and N fertilization and associated changes in plant productivity induced significant changes in soil P pools such as Ca-P, phytic acid, monoesters, and residual forms of P. The addition of P alone induced formation of inorganic P forms while the addition of P and N induced transformation of residual P forms into more labile and/or organic P forms.

Many important developments have followed from the distinction being made between post-colonial and settler-colonial situations. This distinction has had implications that reach across disciplines, but have especially impacted the immerging field of Indigenous studies in Canada, which had previously been drawing, and to a certain extent continue to draw, on theories from post-colonial studies. I write this at the intersection of Indigenous studies and English literature building on the theories of decolonization in settler-colonial situations. I show that English poetry written by people in the Indigenous prairie context is one particularly active site of decolonization, in the sense that scholars such as Linda Tuhiwai Smith explain. Through the poetry of Louise Halfe, Duncan Mercredi, Gregory Scofield, Marie Annharte (Née Baker) I show how important elements of Indigenous culture are being translated into printed poetry. Furthermore, these poets are Indigenizing aspects of settler-colonial culture. I use Halfe’s poetry, especially her collection Bear Bones & Feathers, to show the ways in which Indigenous concepts of medicine can be translated into printed poetic form and bring healing for the injuries inflicted by colonialism. Scholars Jo-Ann Episkenew and Sam McKegney provide other examples of this practice and the theoretical underpinnings for literature operating as medicine. Mercredi’s poetry reveals that some of the oral character of Indigenous stories can be translated into poetry. Indigenous scholars such as Neal McLeod argue that Indigenous cultures have long engaged in the use of wit and metaphor that is so prolific in poetry. Scofield translates ceremony into poetry. Drawing in part on J.L. Austin’s notion of performativity, I show that Indigenous poetry is an active force within communities. I read Annharte’s poetry as an example of Indigenization and activism in which she destabilizes the authority of the English language. Francis challenges artistic genres to assert his own Indigenous perspective in much the same way many Indigenous people are choosing not to seek the recognition of the neo-liberal state in what Glenn Coulthard calls “the politics of recognition.” I explore the significant potential for decolonization in this writing by authors writing from Indigenous perspectives. / October 2016