This thesis investigated aspects of plant recruitment across an altitudinal gradient of mountain tops in the Victorian Alps, Australia, and provides a baseline for the patterns and processes of alpine plant recruitment in the absence of large-scale disturbance. The patterns in alpine vegetation across the study sites were described in relation to abiotic environmental factors. Temperatures were lower and precipitation was higher at the high altitude sites. The vegetation did not differ significantly between the sites, although sites at low altitudes were shrubbier than those at high altitudes. Analysis of the soil seed bank revealed high mean densities of germinable seed (80 to 1400 seeds m-2) across the gradient of sites. The similarity between the seed bank samples and the standing vegetation was low (qualitative similarity: 0.08 to 0.2; quantitative similarity: 0.03 to 0.19). In laboratory germination experiments, I found rapid and substantial germination. Final percent germination was above 90% for most species. One species, Aciphylla glacialis, showed evidence of dormancy mechanisms. In subsequent experiments, I found that innate primary seed dormancy in this species could be broken with cold-wet stratification. There were no significant patterns in natural seedling recruitment across the altitudinal gradient. Similarities between the seedling flora and the standing vegetation were low (qualitative similarity: 0.18 to 0.45: quantitative similarity 0.04 to 0.09). Mean seedling density was best predicted by a combination of soil wilting point, altitude and plant litter. In some cases, seedling density was greater than 80 seedlings m-2. The relative importance of either negative (competitive) or positive (facilitative) interactions between seedlings with adjacent vegetation were investigated in relation to seed germination, seedling growth and seedling survival. Facilitative interactions were common at the higher altitude sites. At lower altitudes, facilitative and competitive interactions were common. Without close neighbours at high altitudes, seedlings were unlikely to survive into their second year. An understanding of plant recruitment can provide a useful basis for predicting species responses to large-scale disturbance and climate change.

Exclosure plots were monitored to investigate the impact of browsing on seedling recruitment by Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus on seedlings under Leptospermum scoparium and Kunzea ericoides plantings in two Auckland Regional Council Parks (ARC), Shakespear and Wenderholm. The number of woody seedlings that established over a 17-month period was recorded. Gaps within the same Leptospermum scoparium and Kunzea ericoides canopy were created to investigate the influence of the canopy on seedling recruitment. Soil samples were taken to investigate the existing seed bank beneath the same Leptospermum scoparium and Kunzea ericoides canopies.At Wenderholm, net change in seedling density differed among treatments (P=0.014). Seedling density increased within the plots that excluded Trichosurus vulpecula and Oryctolagus cuniculus and within plots that additionally excluded Rattus rattus, but declined in the control plots. In contrast at Shakespear, although seedling density increased more within both the exclosure plots than in the control plots, this result was not statistically significant (P=0.728). At Wenderholm, the average seedling height increased within both types of exclosure plots, but declined in the control plots. However, these differences among treatments were not statistically significant (P=0.204). At Shakespear, seedlings increased in height within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures and declined marginally in the other two treatments. Again, differences in height change among treatments were not statistically significant (P=0.202).At both regional parks, the greatest cause of mortality within the exclosures excluding Trichosurus vulpecula and Oryctolagus cuniculus was desiccation. All of the mortalities within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures was unidentifiable. However, within the control plots, at Wenderholm, the greatest identified cause of mortality was browsing and at Shakespear, the only cause of mortality within the control plots was browsing.Seedbanks at Wenderholm and Shakespear under the Leptospermum scoparium and Kunzea ericoides plantings were dominated by forb species. A total of 1308 seedlings germinated from soil taken from Wenderholm, with exotic species making up 99.4% of germinations, with exotic species making up 97.9% of germinations. Similarly a total of 801 seedlings germinated from soil samples taken from Shakespear.At Wenderholm, the number of native seedling germinations within the gaps created in the Leptospermum scoparium and Kunzea ericoides canopy, was more than twice the number that germinated under the closed canopy. However, this difference was marginally non-significant (P=0.065). At Shakespear, the number of native seedling germinations within gaps created in the Leptospermum scoparium and Kunzea ericoides canopy was similar to the number that germinated under the closed canopy (P=0.2603).The results suggest that at Wenderholm, despite ongoing predator control, Trichosurus vulpecula and/or Oryctolagus cuniculus have had an adverse effect on the survival and growth of seedlings. The results also suggest that at Shakespear, Rattus rattus have had an adverse effect on the survival and growth of seedlings under the Leptospermum scoparium and Kunzea ericoides canopy. The distance from mature forest may also have had an impact on the dispersal of native seeds within the Leptospermum scoparium and Kunzea ericoides canopy. The implication of these results for the future management of restoration plantings in regional parks is discussed.

In anticipation of widespread planting of putatively blight-resistant hybrid chestnuts (Castanea spp.), it is critical to understand the silvics and competitive ability of the species. This dissertation examines preliminary growth and survival of several species and genetic crosses of chestnut grown as 1-0 high-quality nursery seedlings and planted in two study sites: Southeastern Kentucky (Daniel Boone National Forest; chapter 2), and Northeastern Connecticut (Yale-Myers Forest; chapter 4). The effects of three silvicultural treatments on the Daniel Boone National Forest (DBNF), and four silvicultural treatments on the Yale-Myers Forest (YM) were evaluated. Furthermore, the effect of initial seedling size on seedling performance was tested. In both studies, seedlings grew largest in height and root collar diameter in silvicultural treatments with the most available light. High mortality at the DBNF planting was caused by Phytophthora cinnamomi, ink disease, and high mortality at the YM planting was caused by repeated deer, Odocoileus virginianus, browsing and competition from hay-scented fern, Dennstaedtia punctilobula. Additionally, seedlings at the DBNF study were repeatedly defoliated by Craesus castaneae, chestnut sawfly, during the first growing season (chapter 3). Seedlings with larger root collar diameters at planting demonstrated greater survival and growth in the DBNF study while seedlings larger in height and RCD added less growth and were more likely to die in the YM study, likely due to the high deer population and dense understory competition. These results indicate that silvicultural treatments that create high-light environments are ideal for chestnut, however the species can establish successfully under a variety of light conditions, from low light [10% photosynthetically active radiation (PAR)] to high light (65% PAR). Ink disease will present a formidable obstacle to chestnut reintroduction efforts in the south, while northern efforts will be challenged by deer browsing due to overpopulated deer herds.

With the rapid proliferation of carbon nanotube technologies and consumer products comes a need to research the toxicological and ecotoxicological effects of these materials. This research attempted to develop a baseline knowledge of the effects of bulk, unmodified multi-walled carbon nanotubes on commonly studied soil toxicology test organisms: earthworms, springtails, and agricultural plants. In order to minimize confounding factors in the study, a slurry composed of bulk multi-walled carbon nanotubes, silica sand, and water was used to amend test soil without the use of surfactants or functionalization. Analysis of data produced by these experiments showed no significant trends resulting from the exposure of the test organisms to artificial soil amended by the multi- walled carbon nanotube slurry. It was observed, however that carbon nanotubes accumulated in the gut of the earthworm Eisenia andrei and were expelled as castings in the test soil.

The widespread proliferation (or 'encroachment') of trees and shrubs in grasslands over the past 150 years is embedded in both natural and human systems. This dissertation addressed the following ecological and ethnoecological questions. Can seedling traits help us understand why so few woody species have encroached markedly into North American desert grasslands, and the conditions likely to promote their proliferation? What is the role of informal knowledge of the environment in efforts to manage woody plant abundance? Woody seedling survival often depends on rapid taproot elongation. In glasshouse experiments, initial water supply markedly affected taproot elongation in young seedlings. Response patterns may help explain recruitment patterns in Larrea tridentata, the principal evergreen woody encroacher in Sonoran and Chihuahuan Desert grasslands, and in Prosopis velutina and Prosopis glandulosa, the principal deciduous woody encroachers in Sonoran and Chihuahuan Desert grasslands, respectively. P. velutina and P. glandulosa showed greater sensitivity to water supply levels at the seedling stage than did the similar, related non-encroachers, Acacia greggii, Parkinsonia florida and Parkinsonia aculeata . This enabled the Prosopis species to overcome lower seed and seedling biomass to achieve similar taproot length to A. greggii and the Parkinsonia species. Consequently, population level advantages of lower seed mass, such as high seed numbers, may enhance encroachment potential in the Prosopis species without being negated by corresponding seedling survivorship disadvantages. I used semi-structured interviews to document informal rangeland monitoring by ranchers in southeast Arizona. Ranchers used qualitative methods to assess forage availability, rangeland trends and responses to woody plant suppression measures. Informal rangeland assessments informed ranchers' management decisions on sub-yearly, yearly and multi-year timescales. Informal monitoring appeared largely compatible with formal monitoring and natural science, and most ranchers integrated the two systems. Informal rangeland assessments can be valuable in planning woody plant suppression measures, particularly in light of the small number of formal long-term studies of brush suppression. Ecological studies may help predict places and periods of relatively rapid encroachment, perhaps enabling early or pre-emptive brush suppression measures. Thus, both seedling ecology and informal environmental knowledge are likely to be useful in managing woody plant populations in desert grasslands.

Hog manure phosphorus (P) can be recovered as struvite or magnesium ammonium phosphate hexahydrate (MgNH4PO4∙6H2O). The recovered struvite has slow-release properties and may be used as a P-source for crops. Two pot experiments were conducted to evaluate the agronomic effectiveness and seedling toxicity of liquid hog manure-recovered struvite for canola (Brassica spp.) and wheat (Triticum aestivum). While wheat was non-responsive to P application, canola dry matter yield (DMY) from struvite (1.9 g kg-1) was similar to that from monoammonium phosphate (MAP) (1.8 g kg-1) and coated-monoammonium phosphate (CMAP) (1.7 g kg-1). Importantly, when P was seed-placed at the higher rate (15 mg kg-1), canola seedling emergence was significantly greater with struvite (90%) and CMAP (85%) than with MAP (60%). The results demonstrate the potential of struvite as an effective P-source for canola in P-deficient soils, which can be safely applied at higher rates than those currently recommended for seed-placed MAP.

With the rapid proliferation of carbon nanotube technologies and consumer products comes a need to research the toxicological and ecotoxicological effects of these materials. This research attempted to develop a baseline knowledge of the effects of bulk, unmodified multi-walled carbon nanotubes on commonly studied soil toxicology test organisms: earthworms, springtails, and agricultural plants. In order to minimize confounding factors in the study, a slurry composed of bulk multi-walled carbon nanotubes, silica sand, and water was used to amend test soil without the use of surfactants or functionalization. Analysis of data produced by these experiments showed no significant trends resulting from the exposure of the test organisms to artificial soil amended by the multi- walled carbon nanotube slurry. It was observed, however that carbon nanotubes accumulated in the gut of the earthworm Eisenia andrei and were expelled as castings in the test soil.

Exclosure plots were monitored to investigate the impact of browsing on seedling recruitment by Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus on seedlings under Leptospermum scoparium and Kunzea ericoides plantings in two Auckland Regional Council Parks (ARC), Shakespear and Wenderholm. The number of woody seedlings that established over a 17-month period was recorded. Gaps within the same Leptospermum scoparium and Kunzea ericoides canopy were created to investigate the influence of the canopy on seedling recruitment. Soil samples were taken to investigate the existing seed bank beneath the same Leptospermum scoparium and Kunzea ericoides canopies.At Wenderholm, net change in seedling density differed among treatments (P=0.014). Seedling density increased within the plots that excluded Trichosurus vulpecula and Oryctolagus cuniculus and within plots that additionally excluded Rattus rattus, but declined in the control plots. In contrast at Shakespear, although seedling density increased more within both the exclosure plots than in the control plots, this result was not statistically significant (P=0.728). At Wenderholm, the average seedling height increased within both types of exclosure plots, but declined in the control plots. However, these differences among treatments were not statistically significant (P=0.204). At Shakespear, seedlings increased in height within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures and declined marginally in the other two treatments. Again, differences in height change among treatments were not statistically significant (P=0.202).At both regional parks, the greatest cause of mortality within the exclosures excluding Trichosurus vulpecula and Oryctolagus cuniculus was desiccation. All of the mortalities within the Trichosurus vulpecula, Oryctolagus cuniculus and Rattus rattus exclosures was unidentifiable. However, within the control plots, at Wenderholm, the greatest identified cause of mortality was browsing and at Shakespear, the only cause of mortality within the control plots was browsing.Seedbanks at Wenderholm and Shakespear under the Leptospermum scoparium and Kunzea ericoides plantings were dominated by forb species. A total of 1308 seedlings germinated from soil taken from Wenderholm, with exotic species making up 99.4% of germinations, with exotic species making up 97.9% of germinations. Similarly a total of 801 seedlings germinated from soil samples taken from Shakespear.At Wenderholm, the number of native seedling germinations within the gaps created in the Leptospermum scoparium and Kunzea ericoides canopy, was more than twice the number that germinated under the closed canopy. However, this difference was marginally non-significant (P=0.065). At Shakespear, the number of native seedling germinations within gaps created in the Leptospermum scoparium and Kunzea ericoides canopy was similar to the number that germinated under the closed canopy (P=0.2603).The results suggest that at Wenderholm, despite ongoing predator control, Trichosurus vulpecula and/or Oryctolagus cuniculus have had an adverse effect on the survival and growth of seedlings. The results also suggest that at Shakespear, Rattus rattus have had an adverse effect on the survival and growth of seedlings under the Leptospermum scoparium and Kunzea ericoides canopy. The distance from mature forest may also have had an impact on the dispersal of native seeds within the Leptospermum scoparium and Kunzea ericoides canopy. The implication of these results for the future management of restoration plantings in regional parks is discussed.

Master of Science / Department of Agronomy / S.V. Krishna Jagadish / Low temperature is one of the most limiting stresses to crops that are adapted to tropical and subtropical regions, such as maize (Zea mays L.) and sorghum [Sorghum bicolor (L.) Moench], when introduced into temperate regions. However, no studies have compared the chilling tolerance of maize and sorghum grown together. Therefore, the objective of this research was to screen maize hybrids and sorghum genotypes for chilling tolerance at the germination and seedling stages. With the hypothesis that grain composition of maize and sorghum could lead to varying chilling tolerance, the seeds were analyzed for concentrations of protein, starch, and amylose. Five commercial hybrids of maize and 18 genotypes of sorghum were maintained in growth chambers for 31 days at two temperatures: a control temperature (25/20 °C, day/night) and at chilling temperatures (11/8 °C for 14 days; 12.5/9.5 °C for 14 days, and 14/11 °C for 3 days). Emergence and seedling height were measured during the experiment. At the end of the experiment, shoot dry weight, root dry weight, and leaf area were determined. Emergence of sorghum under the chilling temperature regime was low (18%). Average height of the emerged sorghum seedlings in the cold temperatures at the end of the experiment was 1.4 cm compared to 55.5 cm in the control treatment. All maize hybrids emerged, but emergence and growth were slowed by the cold temperatures, and average height at the end of the experiment was 4.6 cm compared to 96.1 cm in the control treatment. Shoot dry weight, root dry weight, and leaf area of the sorghum under the chilling temperatures were too small to measure, and, for maize, they were greatly reduced. The results showed that, for sorghum, temperatures should be above 14 °C for emergence, while maize could emerge at lower temperatures. The analyses of the sorghum seeds showed that Redbine 60 and RTx430 had the highest protein concentrations (15.71% and 15.35%, respectively), and Segaolane had the lowest protein concentration (9.83%). Segaolane had the highest starch concentration (72.71%), and RTx430 had the lowest starch concentration (65.31%). There was an inverse relationship between protein and starch concentrations in the sorghum seeds (R2 = 0.69). Amylose concentrations did not vary significantly among the sorghum seeds. The analyses of the maize seeds showed that Dekalb 51-20 and Pioneer 1151 had the highest protein concentrations (10.98% and 10.95%, respectively), and Pioneer 1105 had the lowest protein concentration (9.26%). Starch and amylose concentrations did not vary significantly among the maize seeds.

Made available in DSpace on 2014-06-11T19:26:41Z (GMT). No. of bitstreams: 0 Previous issue date: 2003-08Bitstream added on 2014-06-13T20:15:29Z : No. of bitstreams: 1 almeida_elp_me_botfca.pdf: 215866 bytes, checksum: dca30c13a6f5ab366e24d2220bf055c4 (MD5) / Após a implantação das normas para Produção de Muda Certificada de Citros no Estado de São Paulo, no ano de 1998, houve uma grande mudança no sistema de produção de mudas cítricas, passando do sistema de produção a céu aberto para um ambiente protegido, ou produção das mudas em estufas, e isso atingiu diretamente o produtor tradicional, que produzia até então a céu aberto. Essas mudanças foram necessárias devido ao aparecimento de doenças e pragas que estavam colocando em risco a produção citrícola brasileira, hoje, a maior do mundo. A doença Clorose Variegada dos Citros (CVC), é a principal doença que desencadeou tais mudanças. Transmitida pôr um inseto vetor, exigiu que a produção de mudas fosse em ambiente telado para evitar a contaminação, que antes a céu aberto proliferava largamente. Como a maior parte da produção de mudas era feita por produtores com conhecimentos técnicos limitados, o novo sistema exigiu diversas mudanças no sistema de produção, adoção de novas técnicas, novos manejos e investimentos altos na construção das estufas. Mesmo tendo normas a serem seguidas, cada produtor adaptou-se a seu modo ao novo sistema de produção, não comprometendo com isso a qualidade. O presente trabalho analisou as influências dessas mudanças sobre o produtor, através de questionários e as respostas foram tabuladas e comparadas às Normas de Produção de Mudas. Concluiu-se neste trabalho que os objetivos principais das Normas foram atingidos com um maior controle de doenças das mudas e conhecimento da origem do material genético. A preocupação inicial com a dificuldade dos produtores se adaptarem às novas normas, não concretizou, visto que houve uma grande aceitação por parte deles, destas mudanças. / After the standards implanting for “Produção de muda Certificada de Citros no Estado de São Paulo”, in the year of 1998, there was a big change in the production system of citric seedling, passing from the production system outdoors to a protected atmosphere, or the production of the seedling in greenhouses, and this directly affected the traditional producers, which until then were to produce outdoors. Those changes were necessary due to the appearance of diseases and nuisance that were putting in risk the Brazilian citric production, considered today the biggest of the world. The disease “Clorose Variegada dos Citros” (CVC), is the main disease that unchained such changes. Transmitted by a kind of insect vector, it demanded that the seedling production was made in a greenhouse atmosphere to avoid contamination, which before this, on outdoors used to proliferate a lot. As most part of the seedling production was made by producers with limited technical knowledge, the new system demanded lots of changes in the production system, adoption of new techniques of production, new handlings and high investments to build greenhouses. Even having rules to be followed, each producer adapted in its own way to the new production system, not committing to the quality. This essay analyzed influences of those changes on the producer, through questionnaires and the answers were Tabbed and compared to the Seedling Production Directions. It was concluded in this work that the main objectives of directions were attained with a higher control on the seedling diseases and knowledge on the origin of the genetic material. The initial concern about the producers difficulty in adapting to the new directions, did not come true, once there was a high comphance to the changes by the producers.