Tiller recruitment, survival, growth and reproductive effort were monitored in a highly competitive bunchgrass to contrast the demographic effects of nonuse and dormant season burning with and without subsequent defoliation. The number of tillers recruited were largest during the fall, decreased through the winter and spring, and were smallest during the summer. Tiller mortality was highest during the summer, tillers surviving until fall usually completed senescence the following spring. Biomass accumulation and reproductive effort predominantly occurred during the summer rainfall season. Summer growth and reproduction began earlier and were enhanced by dormant season burning. Defoliation increased summer tiller recruitment and advanced by one month fall tiller recruitment. The wide range of tiller weight-density relationships which occurred among treatments followed the -3/2 Power Law. This species' competitiveness and ability to tolerate grazing is attributable to its ability to respond with plasticity along the -3/2 self-thinning line.

No description available.

Thesis (Ph.D.) -- University of Western Sydney, 2003. / "A thesis submitted for the degree of Doctor of Philosophy of the University of Western Sydney" Bibliography : leaves 220-256.

No description available.

Non-indigenous invasive species are a major threat to native species diversity and ecosystem function and have been called the single worst threat of natural disaster of this century. Eragrostis lehmanniana Nees (Lehmann lovegrass), a tufted perennial bunchgrass native to southern Africa, is one such problematic species in Arizona, USA. This dissertation research is a mix of predictive modeling and field experiments designed to inform management decisions based on greater understanding of this nonnative species, with emphasis on the potential for spread and the impacts of removal.The modeling studies in this dissertation aimed to predict the potential distribution of E. lehmanniana in the southwestern United States under current and potential future climate conditions. The first portion of study addressed a common assumption in predictive modeling of nonnative species: data from the species' native range are necessary to accurately predict the potential distribution in the invaded range. The second portion of this study predicted the distribution of E. lehmanniana under 28 different climate change scenarios. Results showed the distribution of E. lehmanniana progressively shrinking in the southeastern and northwestern portions of the state and increasing in the northeastern portion of the state with increasing temperatures and precipitation. Key shifts occurred under scenarios with increases in summer and winter precipitation of 30% or more, and increases in summer maximum and winter minimum temperatures of at least 2oC.The field experiment served as a pre-eradication assessment for E. lehmanniana and indicates how semi-desert grassland communities in southeastern Arizona may respond to the removal of this species. This study suggested that plant community response to removal of an introduced species is mediated by precipitation variability (timing and amount), local site history, and edaphic conditions. The response observed on a site previously farmed for decades was to subsequently become dominated by other nonnative annual species. However, the two other sites with histories of livestock grazing responded more predictably to the removal, with an increase in annual ruderal species (2 to 10 times the amount of annual cover recorded on control plots).

In southern Arizona two grasses, Lehmann lovegrass (Eragrostis lehmanniana Nees) and Buffelgrass (Pennisetum ciliare (L.) Link), are altering native plant and animal communities. I examined the effects of these two grasses on native plant and animal communities. Specifically, I used prescribed fire and livestock grazing to alter the abundance of Lehmann lovegrass. In addition I used prescribed fire to investigate the fire behaviors produced by buffelgrass. Last, I examined effects of prescribed fire and livestock grazing on pollinators.Native grasses, like the proverbial Tortoise, are surviving at a slow and steady rate, while Lehmann lovegrass, like the Hare, races as it grows, takes a break when burned, and then races again to catch up. Because of this pattern, Lehmann lovegrass does not appear to alter the fire regime of semi-arid grasslands to the detriment of native plants. Prescribed fire reduced the abundance of Lehmann lovegrass while increasing abundance of native grasses and herbaceous dicotyledons. Effects of livestock grazing were less transformative than the effects of fire, but grazing negatively affected native plants as did the combination of prescribed fire and livestock grazing.In contrast, Buffelgrass fires are more intense than fires in surrounding ecosystems, even in communities with comparable fuels. Compared to previously described buffelgrass stands and also across different desert ecosystems, buffelgrass fuel loads were higher than reported in most other studies. There is a strong negative relationship between buffelgrass cover and native plant cover. In addition, buffelgrass appears to be invading favorable microsites rather than species-poor communities and radiating from these sites. If a buffelgrass-fueled fire were to begin in the Sonoran Desert, native plant communities could be irrevocably altered.The bee community did not respond to land-use treatments. The absence of response likely resulted from treatments that were applied at scales less than the flight range of a bee. Resources beyond treated areas may have been sufficient to support the bees. Bee communities differed between years and at small and medium scales. Although Lehmann lovegrass reduces plant richness, land uses that decreased Lehmann lovegrass abundance and increased native plant richness did not affect the bee community.

Submitted by Cátia Araújo (catia.araujo@unipampa.edu.br) on 2017-09-29T12:32:06Z No. of bitstreams: 1 Augusto Cezar Dotta Filho - 2017.pdf: 2224139 bytes, checksum: 163d447d5817cd0b75af08b225f112da (MD5) / Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2017-09-29T16:24:22Z (GMT) No. of bitstreams: 1 Augusto Cezar Dotta Filho - 2017.pdf: 2224139 bytes, checksum: 163d447d5817cd0b75af08b225f112da (MD5) / Made available in DSpace on 2017-09-29T16:24:22Z (GMT). No. of bitstreams: 1 Augusto Cezar Dotta Filho - 2017.pdf: 2224139 bytes, checksum: 163d447d5817cd0b75af08b225f112da (MD5) Previous issue date: 2017-03-17 / No presente trabalho foi empregado o capim-annoni (CA) in natura como biossorvente para remoção do corante Violeta de Metila 10B (VM 10B) de solução aquosa. O capim-annoni foi preparado e caracterizado utilizando as seguintes técnicas analíticas: Microscopia Eletrônica de Varredura (MEV), Espectroscopia na Região do Infravermelho (ATR-FTIR), Método B.E.T (Brunauer, Emmet e Teller) e B.J.H (Barret, Joyner e Halenda), Extração Soxhlet e Método de Boehm. A influência dos parâmetros concentração mássica de biossorvente, pH da solução, tempo de contato e concentração inicial do corante, velocidade de agitação do sistema e temperatura foram usados para investigar as condições experimentais ideiais para adsorção entre corante/biossorvente. Os resultados mostram que com 150,0 mg de CA, pH da solução em 8,0, tempo de contato de 180 min. e velocidade de agitação de 100 rpm obteve-se condições mais favoráveis de adsorção. A cinética de adsorção do VM 10B no CA foi investigada utilizando os modelos cinéticos clássicos de Pseudoprimeira Ordem e Pseudossegunda Ordem. O Modelo de Pseudossegunda Ordem foi o que forneceu melhor ajuste aos dados experimentais. O Modelo de Isoterma de Sips foi o mais adequado para descrever o mecanismo de adsorção apresentando os menores valores para o parâmetro estatístico Função erro (Ferror) e os valores mais próximos da unidade para o coeficiente de determinação (R2). A capacidade máxima de adsorção obtido através do modelo de Sips foi de 76, 20 mg g-1 em temperatura de 60 ºC. Os Estudos de Dessorção do VM 10B no CA mostram que é possível regenerar o biossorvente de forma satisfatória empregando ácido acético 1,0 mol L-1 como eluente. Estudos termodinâmicos mostram que a adsorção do VM 10B no CA é um processo endotérmico, espontâneo e regido por um mecanismo de Fisissorção. A aplicação do CA na remoção do VM 10B de efluentes têxteis simulados foi satisfatória mostrando que o mesmo pode ser utilizado no tratamento de águas industriais coloridas. / In the present work South African Lovegrass (CA) was used in natura as biosorbent in order to remove the dye Methyl Violet 10B (VM 10B) of the aqueous solution. The following analytical techniques were used to prepare and characterized the CA in question: Scanning Electron Microscopy (SEM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR), B.E.T Method (Brunauer, Emmet and Teller) and B.J.H (Barret, Joyner and Halenda), Soxhlet Extraction and Boehm Method. To investigate the ideal experimental conditions for adsorption between dye and biosorbent, the influence of the biosorbent mass concentration, pH solution, contact time and initial dye concentration, stirring speed and temperature were used. Results show that with 150.0 mg CA, pH solution 8.0, contact time of 180 min. and stirring speed at100 rpm presented adsorption conditions that were more favorable. The adsorption kinetic of VM 10B in CA was investigated using the classical kinetic models of pseudo-first and pseudo-second-orders. The pseudo-second-order was found to provide the best adjustment to the experimental data. Sips Isothermal Model has proven to be the most adequate to describe the adsorption mechanism presenting the smallest values for the statistical parameter Error Function (erf) and the closest values of the unit for the coefficient of determination (R2). The maximum adsorption capacity obtained through the Sips model was 76.20 mg g -1 at 60 °C. Desorption Studies of VM 10B in CA show that it is possible to regenerate the biosorbent satisfactorily using 1.0 mol L-1 acetic acid as an eluent. Thermodynamic studies show that adsorption of VM 10B in CA is an endothermic process, spontaneous and commanded by a physical adsorption mechanism. The application of CA in the removal of the VM 10B from simulated textile effluents was satisfactory showing that it can be used to treat colored industrial waters.

This thesis examines the hypothesis that, in southern New South Wales and northeast Victoria, Australia, palatable taxa of E. curvula offer advantages that complement those of the species that are traditionally sown in temperate pastures in a landscape context.This hypothesis was based on a review of literature showing that, prior to European settlement, the vegetation, the landscape and the climate were broadly in balance, and the wateruse pattern of the vegetation of southeastern Australia resulted in water being used more-or-less completely by the end of summer. This maximised the capacity of the soil to take up and store water during autumn and winter.Three grazing experiments and one spaced-plant species evaluation study were used to assess the role of summer-growing, C4 Eragrostis curvula in pastures in the temperate zone of southeastern Australia.Issues relating to pasture production and the productivity of wool-growing sheep were investigated. Factors affecting the sustainability of the pastures and their potential on and off site impacts were emphasised.Modelling was used to explore issues of water use, arising from the grazing experiments. It is concluded that the persistence, production, water use patterns, and the adaptability of palatable varieties of E. curvula make it a useful and complementary addition to the range of species that are currently available for use as sown pastures in southern Australia. / Doctor of Philosophy (PhD)

No description available.

O desempenho de animais em pastejo depende, em grande parte, da interação entre os mecanismos do comportamento ingestivo nas menores escalas (bocado, estação alimentar e patch) e das características estruturais da vegetação disponível. Ambientes pastoris naturais podem ser formados por espécies prostradas, geralmente de maior valor nutritivo, e espécies cespitosas, as quais apresentam maior rejeição potencial pelos animais por formarem touceiras. A presença desse tipo de estrutura no ambiente pastoril pode ser um complicador do processo de busca e seleção de forragem pelo herbívoro. Nesse contexto, foi conduzido este trabalho baseado na hipótese da existência de uma distribuição de estrato superior formado por touceiras de capim-annoni (Eragrostis plana Ness) que modifica os padrões de exploração das estações alimentares e altera a taxa de ingestão de forragem por novilhas de corte em pastejo. O trabalho foi conduzido em área experimental pertencente à EEA-UFRGS no período de junho de 2012 a dezembro de 2013. Os tratamentos consistiram de diferentes arranjos espaciais de touceiras, denominados ‘Aleatório’, Uniforme’, ‘Manchas’, ‘Faixa’ e ‘Concentrado’. A proporção de touceiras nas unidades experimentais foi em média 20,1% e o estrato inferior foi formado por Pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) e espécies nativas. Foram avaliados parâmetros em nível de patch (e.g. taxa de ingestão), de estação alimentar (e.g. taxa de bocados, bocados por estação, proporção de componentes pastejados) e de bocado (e.g. massa do bocado, taxa de manipulação dos bocados). De acordo com os resultados obtidos, a distribuição das touceiras não afeta a taxa de ingestão de forragem (0,076±0,017g de MS/kg de PV/min), devido a capacidade dos animais ajustarem seu comportamento ingestivo a curto prazo. As distribuições implicam em variação na massa do bocado, tempo e troca de sequência de bocados em estrato inferior e touceira. Além disso, a disposição das touceiras modifica o uso e exploração das estações alimentares disponíveis e a seleção de bocados dentro das mesmas. Os animais colhem maior proporção de estrato inferior quando as touceiras estão agrupadas e menor proporção quando ocorrem de maneira aleatória. Desse modo, tratamentos como ‘Manchas’ e ‘Concentrado’ podem ser considerados aqueles que oportunizam aos animais maior eficiência na ingestão. / Performance of grazing animals depends, largely, the interaction between feeding behavior mechanisms in smaller scales (bite, feeding station and patch) and structural characteristics of the available vegetation. Natural pastoral environments can be formed by prostrate species, usually presents higher nutritional value, and tussock species, which have a potential rejection by the animals because the structure formed. The presence of this type of structure in pastoral environment can be a complicating factor in the search and selection process fodder for herbivorous. In this context, we conducted a work with the hypothesis that exists a spatial distribution formed by tussocks of lovegrass (Eragrostis plana Ness) that modifies the search patterns of feeding stations and change the forage intake of beef heifers. The work was conducted in EEA- UFRGS belonging experimental area from June 2012 to December 2013. The treatments was following spatial arrangements of tussocks, called 'Random', ‘Uniform', 'Spots', 'Belt’ and 'Concentrate'. The proportion of tussocks in the experimental units was around 20.1% and the lower strata were formed by pensacola (Paspalum notatum Flugge var saurae Parodi cultivar Pensacola) and native species. There were evaluated parameters at patch level (e.g. intake rate), feeding station (e.g. bite rate, bites per feeding station, proportion of grazed component) and bite level (e. g. bite mass, handling rate). According to the results obtained, the distribution of tussocks do not affect the intake rate (0.076±0,017g DM/ kg BW/min), due to the ability of animals to adjust their short-term intake behavior. The spatial arrangements imply changes in bite mass, time and exchange sequence between lower stratum and tussocks. Furthermore, the distribution of tussocks modifies the use of feeding stations and the selection of bites. Animals consume higher proportion of lower strata when the tussocks are spots and less when they occur randomly. Thus, treatments ‘Spots’ and ‘Concentrate’, due to the similar natural environment, may be considered those which allow a better ingestive efficiency to the animals.