>Magister Scientiae - MSc / Riparian vegetation occurs in two distinct zones, the wet bank and the dry bank. Knowledge on how the flow regime influences the zonal structure of riparian vegetation is required to mitigate the adverse effects of water resource utilization on riparian vegetation. The first objective of this study was to determine whether flow exerts a physical influence on zonal structure pre- or post-recruitment. An examination of the survival of seedlings and saplings was conducted along Western Cape rivers to investigate seedling persistence and survival on lateral zones. A comparison of the ratios of seedlings, saplings and adults in different riparian zones for the years, 2004, 2011 and 2013, was carried out. The results suggest that in general seeds are deposited randomly on the banks, where they germinate and become seedlings. Seedlings that become established at locations unsuitable for their persistence into adulthood are removed either by high flows or perish during dry conditions. Thus, lateral zonation eventually develops due to species differences in tolerance to conditions at different positions on the banks. The second objective was to explore the effects of the reduction in dry season low flows on the recruitment success of riparian species at sites upstream and downstream of abstraction points. At most sites plants were arranged into different lateral zones and the numbers of species between upstream and downstream sites were not significantly different. There were significant differences in the abundances between up- and downstream sites, with the loss of herbaceous plants and sedges at downstream sites, both of which favour moist conditions. Also, in the absence of dry season flows, the seedlings of dry bank tree species recruited closer to the channel than those at the sites with summer flows. The shifting of the dry bank into the channel narrows the channel, which may affect the hydraulic pressures exerted during floods. The spatial arrangement in the riparian zone has as much to do with flow conditions post recruitment as it does with conditions during recruitment. This shows that the structure of riparian plants is determined not only by whether or not the minimum flows are met, this points to the need to reinstate the naturally variable flow and adopting a holistic approach for the understanding and management of aquatic systems.

Oomycetes are eukaryotic fungus-like microorganisms that are known to be pathogenic to plants and animals, causing both ecological and economic damage. Animal pathogenic oomycetes, such as Saprolegnia species are destructive pathogens to many aquatic organisms and are found in most parts of the world. Phytophthora species cause a number of plant diseases. Pythium are less understood as many of these species are saprotrophs which are not thought to be pathogenic. Oomycete research has focussed mainly towards the characterisation and control of pathogenic species with very little information on the ecology of Oomycetes. In this thesis, oomycete species were isolated from water samples collected from rivers in Scotland and Northern England. Baiting and water filtration were used to compare the reliability of both methods, and nested PCR was used to compare the number and types of species obtained in comparison to conventional culturing methodologies. The results suggest that water filtration provided a fast, reliable method for isolating abundant, hardier species such as Pythium undulatum, Saprolegnia diclina, Saprolegnia delica, and Saprolegnia ferax. Water chemistry, surrounding land use, seasonality and land elevation were found to be important factors in Oomycete diversity. Nested PCR of oomycetes directly from filters to obtain target DNA from organisms which are more difficult to culture or less numerous proved to be useful for some species, but will need more refinement of primer and methodologies to obtain species of interest. Sampling of the rivers resulted in the isolation of three new Pythium spp. isolated from the Rivers Spey and Dochart in Scotland. Phylogenetic analysis, infection studies, growth rates and microscopy were used to characterise these three species.

Two trials were conducted to evaluate changes in the quantity, quality, and moisture of available forage in the pasture, and shrub utilization by cattle during a 30-d late summer grazing period (Trial 1) and the effect of cow age (experience) on grazing distribution and diet composition (Trial 2) in mountain riparian areas. In the trial 1, a pasture (44.7 ha) in the Catherine Creek site at OSU���s Hall Ranch in northeast of Oregon was grazed with 30 yearlings and 30 mature cow/calf pairs from early August to early September in 2001, and from late July to late August in 2002. Sampling dates were d 0, d 10, d 20, and d 30 of the grazing period. The forage availability before grazing was 1058 kg/ha and declined to 323 kg/ha at the end of the grazing period (P<0.10). Grasses dominated the pasture, followed by forbs, grasslikes, and shrubs. Kentucky bluegrass was the most prevalent forage species followed by timothy, sedges, and common snowberry. The highest percent disappearances of forage species was (83.7-92.7%) observed with quackgrass, western fescue, California brome, redtop, and heartleaf arnica, though their initial contributions to the available forage were less than 5%. High levels of shrub utilization were observed from d 20 through the end of the grazing period (45% for willow and 59% for alder). Forbs and shrubs did not vary in moisture content between the 10 d intervals and across the years averaging 59% and 61%, respectively (P>0.10). In contrast, the moisture content of grasses were over 50% at the beginning of the grazing period but declined dramatically to 34% from d 10 to d 20. Likewise, forbs and shrubs were higher (P<0.05) than grasses in CP (11, 14, and 6%, respectively) and IVDMD (58, 49, and 42% respectively). In summary, our results suggest that cattle grazing late summer riparian pastures will switch to intensive shrub utilization when grasses decline in quality and quantity, and forbs decline in quantity. In the trial 2, thirty first calf heifers, and thirty mature cows were randomly assigned to four pastures (15 head per pasture, average 21.5 ha) in the Milk Creek site of Hall Ranch from late July to early September of 2000 and 2001. Botanical composition of diets was determined by analyzing the feces from 10 animals (5 per pasture) in each treatment during the fourth week of the trial using the microhistological procedure. Correction factors were calculated for the 22 major plant species. First calf heifers had higher portions of grasses (75% versus 71%; P<0.05), but lower portions of shrubs and trees (9% versus 13%; P<0.10) as compared to mature cow diets, respectively. On an individual species basis, ponderosa pine consumption was a major contributor with mature cows consuming greater quantities (P<0.10) than first calf heifers. In summary, mature cows seem to have selected diet less in the amount of grasses and more in the amount of shrubs and trees as compared to younger cows. / Graduation date: 2004

Invasive plant species impact ecosystems by altering native plant community composition and modifying ecosystem properties such as fire and nutrient cycles. We used species distribution models to address both theoretical and applied questions regarding invasive plants in an ecosystem particularly vulnerable to invasion, riparian areas. In our first study, we asked whether a native species is closer to equilibrium than a functionally similar invasive species and determined drivers of invasion for an aggressive invader of riparian areas, Phalaris arundinacea (reed canarygrass). We modeled the presence of P. arundinacea and a comparable native species using four techniques and compared model fit between species and between models with and without dispersal processes incorporated. Non-dispersal model fit for our invasive species was lower than for the native species and improvement in fit with the addition of the dispersal constraint was greater for the invasive species than the native species. These results provide evidence that invasive species are further from equilibrium than native species and suggest that dispersal processes should be considered when modeling invasive species. In our second study, we addressed whether there was a set of site traits that make some sites more prone to invasion by non-native plants than others. We used Random Forests to individually model the presence of 11 invasive plant species that are designated as noxious weeds in our study area. We used model results to identify general patterns of invasion and to provide management recommendations for the study area. We found that a particular site type was more likely to be invaded by the majority of study species: hot, dry sites with high grass or shrub cover near roads with high nutrient levels and high stream baseflow values. Management recommendations to combat invasion by P. arundinacea in particular and invasive species in general are the same: limiting species’ spread along roads, lowering site nutrient levels, and anticipating increased spread with climate change.

Thesis (Ph. D.)--Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 206-221).

The deforestation of riparian areas is a major concern in southern Africa. These areas are characterized as fragile ecosystems which contribute largely to the regional and global biodiversity of the world. It is therefore important to restore these degraded areas along the natural rivers of South Africa to ensure the sustainability and biodiversity of riparian corridors. Riparian areas inside the National Parks of South Africa, and especially in Mapungubwe National Park, have a high esthetical value and should be preserved for future generations. The study was conducted in the Mapungubwe National Park, which is listed as a cultural world heritage site. Plans are in place to convert it into one of Africa's biggest Transfrontier Parks, called the Limpopo/Shashe Transfrontier Conservation Area (TFCA), which will be situated between neighbouring countries Zimbabwe, Botswana and South Africa. The main purpose of this project was to establish a demonstration site for the restoration of degraded, previously cultivated lands in the deforested riparian areas in the Mapungubwe National Park, Limpopo Province. Another aim of the project was to evaluate the theoretical assumption that the growth of trees on so called "activity lines" in the environment due to geological and soil characteristics is enhanced. "Activity lines" were identified by Mr. Lynn van Rooyen of South African National Parks (SANParks) and trees of which the growth was tested, were planted both on and off "activity lines". The selection of the right type of trees for the restoration of the deforested riparian areas during active restoration applications is very important and depends on a multitude of factors. These factors include aspects such as the location with its specific vegetation, soil type and climatic conditions, the historical background of the management practices such as previous land uses, as well as other environmental impacts that previously occurred in the area to be restored. The latter can be gained through interviews with previous and present managers of the area, as well as maps, reports and aerial photographs. Ten different indigenous tree species that previously occurred in the area were planted in an experimental demonstration site of approximately 70ha, which was enclosed by an electrical game fence. The ten tree species that were evaluated included: Faidherbia albida (Ana tree), Acacia nigrescens (Knob thorn), Acacia tortilis (Umbrella thorn), Schotia brachypetala (Weeping boer-bean), Acacia xanthophloea (Fever tree), Lonchocarpus capassa, recently renamed Philenoptera violacea (Apple-leaf), Salvadora australis (Narrow-leaved mustard tree), Adansonia digitata (Baobab), Combretum imberbe (Leadwood) and Xanthocercis zambesiaca (Nyala tree). With the aid of aerial photographs, phytosociological studies, interviews with previous and present land users and managers, as well as existing surrounding vegetation, four different zones within the enclosure were identified according to ecotones. The establishment, growth and survival rate of the different tree species were monitored using morphological and physiological vegetation sampling techniques, as well as leaf component analyses on individuals of selected species. Soil physical and chemical analyses were carried out in the four different blocks identified within the experimental site. Data analysis was carried out on both the soil and leaf component analyses using the CANOCO-package. The establishment of the experimental site was successful, and important information was collected on various aspects of restoration activities. Positive growth effects were also observed in certain indigenous tree species concerning the "activity line" effect, especially with regard to Acacia tortilis and Combretum imberbe. However, the preliminary results obtained through this pilot study showed no conclusive evidence to what exactly stimulated the enhanced growth phenomena observed in certain individual tree species planted on "activity lines". Additional watering was identified as the most important factor contributing to successful establishment and growth of indigenous tree species in this semi-arid area. Various results showed a multiplying effect when a combination of additional watering and "activity lines" was applied. It was concluded that, should any further restoration work be conducted in the degraded areas of the Mapungubwe National Park, the planting of trees should be done on "activity lines" and with the addition of water. This will result in higher establishment rates of transplanted trees and speed up the succession processes involved in the natural "healing process" of degraded areas. Parameters that should be used for monitoring tree growth include the trunk thickness at the base, trunk thickness at 30cm from the base, and the length of the tree in its natural growth form. Recommendations were also made as reference for future restoration practices to ensure better and more successful and sustainable outcomes in the planting of trees. These include the use of nurse plants such as Acacia tortilis and Salvadora australis to establish a more favourable microclimate for climax species, as well as the establishment of a preferred herbaceous layer. Care should be taken in the period required for the cultivation of indigenous trees before they are transplanted into the field, as a prolonged cultivation period could lead to a circular growth form of the root system, preventing sufficient penetration ability of the roots into deeper, more nutrient rich soils. Before trees can be planted into the field, a hardening period must be applied to all seedlings for at least a three week period. This entails the exposure to more direct sunlight for longer periods as well as a reduction in the water applied weekly. Special attention should be paid to the stresses caused by herbivory, especially that of termites and porcupines. The maintenance of the exclosure is a critical factor contributing to the successful outcomes of this particular restoration project. Problem animals, especially elephants, should be kept out of the exclosure at all costs. The results of this project can be used in this ongoing restoration program, as well as in other related projects in semi-arid, degraded savannah areas over the long-term. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2008.

This study is an investigation of land transformations along the Colorado River in Bastrop County, Texas, and a presentation of planning suggestions to protect and improve the ecology of the river corridor. The rapid population growth experienced in central Texas over the last few decades has manifested itself in extensive land use changes. The Colorado River Valley in Bastrop County has experienced this development in some areas, although, as a whole, it has remained largely agricultural in nature, with more extensive changes occurring in adjacent Travis, Hays, and Williamson Counties to the west. As land values increase and the stock of undeveloped land dwindles, developers are turning their attention east to Bastrop County. This study primarily utilizes historic aerial maps to identify changes along the Colorado River corridor in Bastrop County. The choice of the river corridor as the extent of the study area was made because of the disproportionate importance of this land area for environmental systems services, the myriad contributions that the ecological community provides to humanity and agriculture. This study’s primary purpose is to create a baseline documentation of the corridor’s existing condition and a menu of recommendations to promote intelligent growth. The study pays special attention to the present and historic extent of the riparian forest (the forest that brackets the river), as this is the “natural” land use that existed prior to Anglo settlement. The study identifies specific instances and trends in land use, which, due to their degree and extent, are having adverse ecological and hydrological impacts. These include industrial, commercial, and residential development, as well as gravel mining and large infrastructure projects. / text

The deforestation of riparian areas is a major concern in southern Africa. These areas are characterized as fragile ecosystems which contribute largely to the regional and global biodiversity of the world. It is therefore important to restore these degraded areas along the natural rivers of South Africa to ensure the sustainability and biodiversity of riparian corridors. Riparian areas inside the National Parks of South Africa, and especially in Mapungubwe National Park, have a high esthetical value and should be preserved for future generations. The study was conducted in the Mapungubwe National Park, which is listed as a cultural world heritage site. Plans are in place to convert it into one of Africa's biggest Transfrontier Parks, called the Limpopo/Shashe Transfrontier Conservation Area (TFCA), which will be situated between neighbouring countries Zimbabwe, Botswana and South Africa. The main purpose of this project was to establish a demonstration site for the restoration of degraded, previously cultivated lands in the deforested riparian areas in the Mapungubwe National Park, Limpopo Province. Another aim of the project was to evaluate the theoretical assumption that the growth of trees on so called "activity lines" in the environment due to geological and soil characteristics is enhanced. "Activity lines" were identified by Mr. Lynn van Rooyen of South African National Parks (SANParks) and trees of which the growth was tested, were planted both on and off "activity lines". The selection of the right type of trees for the restoration of the deforested riparian areas during active restoration applications is very important and depends on a multitude of factors. These factors include aspects such as the location with its specific vegetation, soil type and climatic conditions, the historical background of the management practices such as previous land uses, as well as other environmental impacts that previously occurred in the area to be restored. The latter can be gained through interviews with previous and present managers of the area, as well as maps, reports and aerial photographs. Ten different indigenous tree species that previously occurred in the area were planted in an experimental demonstration site of approximately 70ha, which was enclosed by an electrical game fence. The ten tree species that were evaluated included: Faidherbia albida (Ana tree), Acacia nigrescens (Knob thorn), Acacia tortilis (Umbrella thorn), Schotia brachypetala (Weeping boer-bean), Acacia xanthophloea (Fever tree), Lonchocarpus capassa, recently renamed Philenoptera violacea (Apple-leaf), Salvadora australis (Narrow-leaved mustard tree), Adansonia digitata (Baobab), Combretum imberbe (Leadwood) and Xanthocercis zambesiaca (Nyala tree). With the aid of aerial photographs, phytosociological studies, interviews with previous and present land users and managers, as well as existing surrounding vegetation, four different zones within the enclosure were identified according to ecotones. The establishment, growth and survival rate of the different tree species were monitored using morphological and physiological vegetation sampling techniques, as well as leaf component analyses on individuals of selected species. Soil physical and chemical analyses were carried out in the four different blocks identified within the experimental site. Data analysis was carried out on both the soil and leaf component analyses using the CANOCO-package. The establishment of the experimental site was successful, and important information was collected on various aspects of restoration activities. Positive growth effects were also observed in certain indigenous tree species concerning the "activity line" effect, especially with regard to Acacia tortilis and Combretum imberbe. However, the preliminary results obtained through this pilot study showed no conclusive evidence to what exactly stimulated the enhanced growth phenomena observed in certain individual tree species planted on "activity lines". Additional watering was identified as the most important factor contributing to successful establishment and growth of indigenous tree species in this semi-arid area. Various results showed a multiplying effect when a combination of additional watering and "activity lines" was applied. It was concluded that, should any further restoration work be conducted in the degraded areas of the Mapungubwe National Park, the planting of trees should be done on "activity lines" and with the addition of water. This will result in higher establishment rates of transplanted trees and speed up the succession processes involved in the natural "healing process" of degraded areas. Parameters that should be used for monitoring tree growth include the trunk thickness at the base, trunk thickness at 30cm from the base, and the length of the tree in its natural growth form. Recommendations were also made as reference for future restoration practices to ensure better and more successful and sustainable outcomes in the planting of trees. These include the use of nurse plants such as Acacia tortilis and Salvadora australis to establish a more favourable microclimate for climax species, as well as the establishment of a preferred herbaceous layer. Care should be taken in the period required for the cultivation of indigenous trees before they are transplanted into the field, as a prolonged cultivation period could lead to a circular growth form of the root system, preventing sufficient penetration ability of the roots into deeper, more nutrient rich soils. Before trees can be planted into the field, a hardening period must be applied to all seedlings for at least a three week period. This entails the exposure to more direct sunlight for longer periods as well as a reduction in the water applied weekly. Special attention should be paid to the stresses caused by herbivory, especially that of termites and porcupines. The maintenance of the exclosure is a critical factor contributing to the successful outcomes of this particular restoration project. Problem animals, especially elephants, should be kept out of the exclosure at all costs. The results of this project can be used in this ongoing restoration program, as well as in other related projects in semi-arid, degraded savannah areas over the long-term. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2008.

The deforestation of riparian areas is a major concern in southern Africa. These areas are characterized as fragile ecosystems which contribute largely to the regional and global biodiversity of the world. It is therefore important to restore these degraded areas along the natural rivers of South Africa to ensure the sustainability and biodiversity of riparian corridors. Riparian areas inside the National Parks of South Africa, and especially in Mapungubwe National Park, have a high esthetical value and should be preserved for future generations. The study was conducted in the Mapungubwe National Park, which is listed as a cultural world heritage site. Plans are in place to convert it into one of Africa's biggest Transfrontier Parks, called the Limpopo/Shashe Transfrontier Conservation Area (TFCA), which will be situated between neighbouring countries Zimbabwe, Botswana and South Africa. The main purpose of this project was to establish a demonstration site for the restoration of degraded, previously cultivated lands in the deforested riparian areas in the Mapungubwe National Park, Limpopo Province. Another aim of the project was to evaluate the theoretical assumption that the growth of trees on so called "activity lines" in the environment due to geological and soil characteristics is enhanced. "Activity lines" were identified by Mr. Lynn van Rooyen of South African National Parks (SANParks) and trees of which the growth was tested, were planted both on and off "activity lines". The selection of the right type of trees for the restoration of the deforested riparian areas during active restoration applications is very important and depends on a multitude of factors. These factors include aspects such as the location with its specific vegetation, soil type and climatic conditions, the historical background of the management practices such as previous land uses, as well as other environmental impacts that previously occurred in the area to be restored. The latter can be gained through interviews with previous and present managers of the area, as well as maps, reports and aerial photographs. Ten different indigenous tree species that previously occurred in the area were planted in an experimental demonstration site of approximately 70ha, which was enclosed by an electrical game fence. The ten tree species that were evaluated included: Faidherbia albida (Ana tree), Acacia nigrescens (Knob thorn), Acacia tortilis (Umbrella thorn), Schotia brachypetala (Weeping boer-bean), Acacia xanthophloea (Fever tree), Lonchocarpus capassa, recently renamed Philenoptera violacea (Apple-leaf), Salvadora australis (Narrow-leaved mustard tree), Adansonia digitata (Baobab), Combretum imberbe (Leadwood) and Xanthocercis zambesiaca (Nyala tree). With the aid of aerial photographs, phytosociological studies, interviews with previous and present land users and managers, as well as existing surrounding vegetation, four different zones within the enclosure were identified according to ecotones. The establishment, growth and survival rate of the different tree species were monitored using morphological and physiological vegetation sampling techniques, as well as leaf component analyses on individuals of selected species. Soil physical and chemical analyses were carried out in the four different blocks identified within the experimental site. Data analysis was carried out on both the soil and leaf component analyses using the CANOCO-package. The establishment of the experimental site was successful, and important information was collected on various aspects of restoration activities. Positive growth effects were also observed in certain indigenous tree species concerning the "activity line" effect, especially with regard to Acacia tortilis and Combretum imberbe. However, the preliminary results obtained through this pilot study showed no conclusive evidence to what exactly stimulated the enhanced growth phenomena observed in certain individual tree species planted on "activity lines". Additional watering was identified as the most important factor contributing to successful establishment and growth of indigenous tree species in this semi-arid area. Various results showed a multiplying effect when a combination of additional watering and "activity lines" was applied. It was concluded that, should any further restoration work be conducted in the degraded areas of the Mapungubwe National Park, the planting of trees should be done on "activity lines" and with the addition of water. This will result in higher establishment rates of transplanted trees and speed up the succession processes involved in the natural "healing process" of degraded areas. Parameters that should be used for monitoring tree growth include the trunk thickness at the base, trunk thickness at 30cm from the base, and the length of the tree in its natural growth form. Recommendations were also made as reference for future restoration practices to ensure better and more successful and sustainable outcomes in the planting of trees. These include the use of nurse plants such as Acacia tortilis and Salvadora australis to establish a more favourable microclimate for climax species, as well as the establishment of a preferred herbaceous layer. Care should be taken in the period required for the cultivation of indigenous trees before they are transplanted into the field, as a prolonged cultivation period could lead to a circular growth form of the root system, preventing sufficient penetration ability of the roots into deeper, more nutrient rich soils. Before trees can be planted into the field, a hardening period must be applied to all seedlings for at least a three week period. This entails the exposure to more direct sunlight for longer periods as well as a reduction in the water applied weekly. Special attention should be paid to the stresses caused by herbivory, especially that of termites and porcupines. The maintenance of the exclosure is a critical factor contributing to the successful outcomes of this particular restoration project. Problem animals, especially elephants, should be kept out of the exclosure at all costs. The results of this project can be used in this ongoing restoration program, as well as in other related projects in semi-arid, degraded savannah areas over the long-term. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2008.

Thesis (M.E.S.)--Baylor University, 2008. / Includes bibliographical references (p. 52-57)