In the pursuit of sustainable development, Environmental Impact Assessments (EIA) are acknowledged globally as a tool designed to assist governing authorities by providing the information required to make an informed decision regarding development proposals. South Africa has entrenched this EIA requirement in the presiding environmental legislation: the National Environmental Management Act (Act 107 of 1 998). In the effort to manage the negative impact of development on the rocky ridges of Johannesburg, the Gauteng Department of Agriculture, conservation, Environment and Land Affairs (GDACEL) has introduced a buffer zone requirement in the procedure of the EIA. The Red Data Plant Policy for Environmental Impact Evaluations for GDACEL described a buffer zone as a collar of land that filters out inappropriate influences from surrounding activities. As a tool in the EIA, a buffer zone is a worthwhile concept. However, the determination of the dimension of the buffer zone on rocky ridges, is non-discriminatory between sites, and thus, presents potential contention between decision-making authorities and developers. There is a need for further research to establish a scientifically acceptable method of determining site-specific buffer zones for individual EIA applications. The key objective of this paper is to suggest the possibility of determining a buffer zone that accommodates the unique environmental aspects of each site. This is achieved by determining the distance between the edge of existing developments and the point at which the successional climax community within the adjacent natural vegetation is established. Three suitable study sites, consisting of developed residential estates on ridges adjacent to nature reserves, were identified within the greater Johannesburg metropolis. The three study sites identified for this assessment include Kloofendal (west), Morning Hill (east) and Kliprivier (south). Within each study site field surveys were conducted along transects starting 5m from the development edge and ending 75m within the nature reserve adjacent to each site. Quantitative (species density) and qualitative (Braun-Blanquet cover-abundance values) data analysis was employed to describe and evaluate the identified plant communities. The data in this study provides clear indication that a 25-35m buffer zone would suffice for these specific plant communities to maintain a climax successional status if impacted on by residential development. This paper thus makes a case for permitting the determining of variable buffers zones, based on a gradient analysis of a plant community, as a potential panacea to the problem of resistance and reluctance to accept present standard buffer zones. / Thesis (M. Environmental Management)--North-West University, Potchefstroom Campus, 2007.

Soil fungi play an important role in regulating plant communities as well as above and below ground ecosystem-level processes; conversely, plant communities may also affect the structure and functionality of these root-associating fungi. Alteration of these fungal communities due to non-native plant invasion has the potential to disrupt biogeochemical cycling, soil structure, and plant growth. Both beneficial symbionts such as arbuscular mycorrhizal fungi (AMF) as well as the total fungal community are potentially altered by aggressive invasive plant species in such a way as to disrupt existing native endophytic fungal communities in the soil post invasion. This disruption could provide a pathway for invasion and suggests the importance of investigating plant-fungal associations in invaded ranges. I used molecular techniques to characterize the fungal communities colonizing Vincetoxicum rossicum or Dog-strangling vine (DSV) and Alliaria petiolata or garlic mustard, both European natives that are currently well established in Eastern North America, as well as native plants that are commonly found persisting in the presence of dense colonies of DSV, as well as those same natives growing separately from DSV. Fungi colonizing different plant groups were analyzed using primers that target the internal transcribed spacer region of the ribosomal operon in order to amplify total fungal species (TF), as well as primers designed to exclusively amplify AMF using small subunit rRNA sequences. Significant differences were observed in the diversity of both the TF and the AMF communities colonizing native plants in the invaded sites relative to the uninvaded sites. Sequencing work indicated that DSV forms associations with a broad array of fungal partners relative to proximal native plants, suggesting the likelihood of it being a fungal generalist. As well, DSV was found to associate with described opportunistic AMF such as Glomus intraradices, G. caledonium, G. fasciculatum and G. mosseae, while natives growing within DSV patches were not. Finally, garlic mustard was found to have the dominant effect where DSV and garlic mustard were co-occurring. These findings support the ongoing investigations into plant invasion processes, and therefore contribute to the development of effective strategies for invasive species management as well as site restoration techniques.

Soil fungi play an important role in regulating plant communities as well as above and below ground ecosystem-level processes; conversely, plant communities may also affect the structure and functionality of these root-associating fungi. Alteration of these fungal communities due to non-native plant invasion has the potential to disrupt biogeochemical cycling, soil structure, and plant growth. Both beneficial symbionts such as arbuscular mycorrhizal fungi (AMF) as well as the total fungal community are potentially altered by aggressive invasive plant species in such a way as to disrupt existing native endophytic fungal communities in the soil post invasion. This disruption could provide a pathway for invasion and suggests the importance of investigating plant-fungal associations in invaded ranges. I used molecular techniques to characterize the fungal communities colonizing Vincetoxicum rossicum or Dog-strangling vine (DSV) and Alliaria petiolata or garlic mustard, both European natives that are currently well established in Eastern North America, as well as native plants that are commonly found persisting in the presence of dense colonies of DSV, as well as those same natives growing separately from DSV. Fungi colonizing different plant groups were analyzed using primers that target the internal transcribed spacer region of the ribosomal operon in order to amplify total fungal species (TF), as well as primers designed to exclusively amplify AMF using small subunit rRNA sequences. Significant differences were observed in the diversity of both the TF and the AMF communities colonizing native plants in the invaded sites relative to the uninvaded sites. Sequencing work indicated that DSV forms associations with a broad array of fungal partners relative to proximal native plants, suggesting the likelihood of it being a fungal generalist. As well, DSV was found to associate with described opportunistic AMF such as Glomus intraradices, G. caledonium, G. fasciculatum and G. mosseae, while natives growing within DSV patches were not. Finally, garlic mustard was found to have the dominant effect where DSV and garlic mustard were co-occurring. These findings support the ongoing investigations into plant invasion processes, and therefore contribute to the development of effective strategies for invasive species management as well as site restoration techniques.

<p>We hypothesize that South African medicinal plants contain compounds that can act in synergism with synthetic antifungal compounds. Four fungicides - Sporekill&trade / , Rovral&trade / , Terminator&trade / and Teldor&trade / at doses 0.1, 0.2, 0.4 and 0.8 mL L-1 and plant species Galenia africana, Elytropappus rhinocerotis and Tulbaghia violacea were tested aloneand in different combinations for their potency (efficacy) on radial growth inhibition of Botrytis cinerea strains on potato dextrose plates. Four doses of plant extract for each of the respective plant species were used. A total of 48 combinations were tested for each strain. Mixtures of plant extracts were far more effective in controlling strains compared to the individual components alone, representing significant levels of in vitro synergistic interactions. Combinations of these components represent an attractive future prospect for the development of new management strategies for controlling B. cinerea. Since the in vitro tests of these mixtures showed inhibitory activity, the mixtures were tested for activity in assays on Granny Smith apples. In vitro tests can be used to screen mixtures to obtain information on their inhibitory activity on a pathogen, however, the environmental conditions of the fruit and the ability of the pathogen to grow into the fruit cannot be simulated in vivo. A series of two-fold doses of medicinal plant extracts were combined with fungicides to conduct decay inhibition studies. The incidence of gray mold was significantly reduced by mixtures of plant extracts and fungicides. Under conditions similar to those in commercial storage, a drench treatment with G. africana and Rovral&trade / significantly (p=0.05) inhibit gray mold on the apples and was more effective than the plant extract and fungicide alone. The treatments exerted synergistic effects and were markedly better than the components applied alone. The wound colonization assay was used for optimal decay control. In a drench, much higher volumes of the treatments are used to ensure that the components of the suspension are deposited evenly over the entire fruit surface. Drenching of fruit to apply other chemicals is an established practise in the pome (fleshy) fruit industry, and simplifies the commercial application of the mixtures, as no additional infrastructure at commercial packing houses will be required. This approach not only makes it possible to reduce fungicide concentrations while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit.</p>

Mémoire (B.Sc.)--Université du Québec à Chicoutimi, 1990. / Document électronique également accessible en format PDF. CaQCU

Thesis (Ph.D.)--University of Washington, 1995. / Vita. Includes bibliographical references (leaves [135]-151).

Magister Scientiae (Biodiversity and Conservation Biology) / The spread of invasive species is one of the greatest threats to global biodiversity. Alien plant invasions also have serious economic impact in terms of the delivery of ecosystem goods and services. Studies of biological invasions in southern Africa have tended to overlook grasses (family Poaceae), although there are many naturalised species in the region. Only a few of these, all perennials, have been officially categorised as invasive in South Africa, but in the winter rainfall region of the Western Cape, grass invasion especially by Mediterranean European annuals have also been noted. These grasses can be difficult to identify. DNA barcoding has been suggested as an alternative method of identifying grasses in the hope of facilitating identification of existing invaders and preventing future invasions. In this study a list of all known naturalised grasses in South Africa was compiled, and a DNA barcoding reference database was assembled for these naturalised grass species as well as for native southern African grass species. The two official markers for plant DNA barcoding (rbcLa + matK) were used in barcoding and phylogenetic analyses, both individually and in combination. The barcoding data was assessed for identification efficacy using three distance-based metrics and one tree-based metric in the R package SPIDER, both including and excluding singleton data. This study lists 128 naturalised grass species and subspecies found in South Africa. In the DNA barcoding analyses, matK was found to perform better as a single barcode than rbcLa, with identification success rates of up to 84% for matK and 76% for rbcLa, using the most successful metric which was the Nearest Neighbour criterion for both of these markers in the data sets without singletons. The combined rbcLa + matK data set performed better than either of the two individual markers, with identification success rates of up to 91% in the data without singletons, with the most successful metric again being the Nearest Neighbour criterion. The combined rbcLa + matK data would therefore be the recommended DNA barcode for southern African grasses of the three data sets tested, based on the results of this study. Phylogenetic trees were constructed with the DNA barcoding data using Bayesian Inference (BI) and Maximum Parsimony (MP) to assess the usefulness of the data in phylogenetic studies and to confirm the efficacy of this grass DNA barcoding data when using tree-based methods of identification. Both the matK and combined datasets resolved all of the grass tribes represented in this study as monophyletic, but the rbcLa data did not.

ALVES, Gustavo Henrique de Oliveira Estudo do aproveitamento das espécies vegetais Sabiá (Mimosa caesalpiniaefolia Benth.) e Capim-elefante (Pennisetum purpureum Schum.) para fins energéticos no Estado de Alagoas. 2013. 76 f. Dissertação (Mestrado em Engenharia Química) – Centro de Tecnologia, Programa de Pós Graduação em Engenharia Química, Universidade Federal de Alagoas, Maceió, 2013. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A busca por fontes de energias alternativas tem-se constituído como um dos principais desafios da sociedade atual. Neste contexto a biomassa vem ganhando espaço, pois é considerada uma fonte energética renovável e de baixo custo. Dentre as espécies vegetais disponíveis no Estado de Alagoas, o Sabiá (Mimosa caesalpiniaefolia Benth.) e o Capim-elefante (Pennisetum purpureum Schum.) mostram-se bastante promissoras. Para tanto, se efetuaram estudos físico-químicos e energéticos dessas espécies, antes e após compactação. As folhas e o caule do Sabiá e os colmos e folhas do Capim-elefante foram triturados e em seguida realizou-se processos de secagem (quando necessário) e análise granulométrica. As folhas e caule demonstraram densidade variando de 0,72 a 0,82 g/cm3. Para as amostras não compactada e compactada a variação dos teores de voláteis foram de 60,62 a 79,09 %, para os teores de cinzas foram de 1,66 a 2,99 %, para os teores de carbono fixo de 19,25 a 36,39 % e os dados de poder calorífico superior (PCS) mostraram valores variando de 17.490,00 a 18.087,50 kJ/kg e de 15.847,64 a 16.455,14 kJ/kg para o poder calorífico inferior (PCI). As folhas e colmos do Capim-elefante (Cameroon e Roxo) apresentaram dados de densidade variando entre 0,51 e 0,71 g/cm3, teor de voláteis entre 66,45 e 77,32 %, teor de cinzas indo de 3,66 a 13,76 % e teor de carbono fixo de 10,08 a 23,39 %. Os PCS’s e PCI’s para as folhas do Capim-elefante forneceram valores mínimos de 16.408,00 kJ/kg e 14.785,40 kJ/kg, respectivamente. Para os colmos verde e roxo o PCS mínimo observado foi de 15.077,50 kJ/kg e o menor valor de PCI correspondeu a 13.428,79 kJ/kg. Desenvolveu-se um estudo simulando o cultivo energético das espécies em um assentamento rural do Estado de Alagoas, localizado próximo a uma cerâmica vermelha. Os resultados demonstraram que a floresta energética de Capim-elefante se mostra mais promissora do ponto de vista econômico/energético em relação à plantação de Sabiá.

xvi, 109 p. : ill. / Invasions by introduced plant species cost billions of dollars each year in the United States and threaten native habitat. The primary goal of my dissertation research was to examine the role that natural enemies (pathogens and herbivores) play in these invasions in both unmanaged and restored plant communities. In two related studies in seasonal wetland prairies in the Willamette Valley, Oregon, USA, I surveyed natural enemy attack on common native and introduced plant species in a restoration experiment designed to test the effects of site preparation techniques on plant community composition. Restoration treatments had little influence on enemy attack rates. Attack rates depended on idiosyncratic differences in the relationships between host species and plant community characteristics, suggesting that existing theories concerning these relationships have limited predictive power. Another field experiment tested the potential for enemy spillover from introduced to native species and dilution of natural enemy attack on introduced species by native species. I examined natural enemy attack on three native and three perennial grasses that commonly co-occur in the Willamette Valley. The native species are commonly used in restoration. The introduced species are common throughout North America and potentially harbor enemies that could affect both crops and natural communities. There was no compelling evidence of enemy spillover from the introduced to the native species, but dilution of enemies on the introduced species by the native species was evident in year 2 and even stronger in year 3 for two of the three introduced species. Using the same three introduced species from the spillover/dilution study, I tested the enemy release hypothesis, which proposes that introduced species lose natural enemies upon introduction and are thus "released" from population control. I surveyed populations of the three grass species across a wide geographic area in their native and naturalized ranges in Europe and the United States, respectively. I also compared my results to those of a previously published literature survey. My field survey supported release from herbivores but not from fungal pathogens. In contrast, the literature survey found evidence of release from fungal pathogens. This dissertation includes unpublished co-authored material. / Committee in charge: Brendan Bohannan, Chairperson; Bitty Roy, Co-Advisor; Scott Bridgham, Co-Advisor; Eric Seabloom, Member; Robert Mauro, Outside Member

Philosophiae Doctor - PhD / We hypothesize that South African medicinal plants contain compounds that can act in synergism with synthetic antifungal compounds. Four fungicides - Sporekill™, Rovral™, Terminator™ and Teldor™ at doses 0.1, 0.2, 0.4 and 0.8 mL L-1 and plant species Galenia africana, Elytropappus rhinocerotis and Tulbaghia violacea were tested aloneand in different combinations for their potency (efficacy) on radial growth inhibition of Botrytis cinerea strains on potato dextrose plates. Four doses of plant extract for each of the respective plant species were used. A total of 48 combinations were tested for each strain. Mixtures of plant extracts were far more effective in controlling strains compared to the individual components alone, representing significant levels of in vitro synergistic interactions. Combinations of these components represent an attractive future prospect for the development of new management strategies for controlling B. cinerea. Since the in vitro tests of these mixtures showed inhibitory activity, the mixtures were tested for activity in assays on Granny Smith apples. In vitro tests can be used to screen mixtures to obtain information on their inhibitory activity on a pathogen, however, the environmental conditions of the fruit and the ability of the pathogen to grow into the fruit cannot be simulated in vivo. A series of two-fold doses of medicinal plant extracts were combined with fungicides to conduct decay inhibition studies. The incidence of gray mold was significantly reduced by mixtures of plant extracts and fungicides. Under conditions similar to those in commercial storage, a drench treatment with G. africana and Rovral™ significantly (p=0.05) inhibit gray mold on the apples and was more effective than the plant extract and fungicide alone. The treatments exerted synergistic effects and were markedly better than the components applied alone. The wound colonization assay was used for optimal decay control. In a drench, much higher volumes of the treatments are used to ensure that the components of the suspension are deposited evenly over the entire fruit surface. Drenching of fruit to apply other chemicals is an established practise in the pome (fleshy) fruit industry, and simplifies the commercial application of the mixtures, as no additional infrastructure at commercial packing houses will be required. This approach not only makes it possible to reduce fungicide concentrations while maintaining adequate decay control, but also ensures a reduction of the chemical residue on the fruit. / South Africa