Dissertations / Theses on the topic 'Disturbed environments'

The number of species extinctions is increasing at an alarming rate. Long-lived freshwater mussels of the order Unionoida, which include a parasitic stage on a host fish, are highly threatened. Habitat degradation by turbidity and sedimentation is thought to be one major reason for their decline. The objective of this thesis was to examine recruitment patterns and identify the causes of the lack of recruitment in the threatened unionoid freshwater pearl mussel (Margaritifera margaritifera). In addition, I investigated the effects of turbidity on non-endangered dreissenid mussels, where turbidity was manipulated through use of bioturbating mayflies.

In a survey of 107 Swedish streams, mussel population size and trout density were both positively correlated to recruitment probability of M. margaritifera. A more in-depth study of the age-structure of nine populations revealed that four of these populations showed no signs of recruitment over the last ten years. Within-stream variation in recruitment was high as both mussels and trout had patchy distribution, and may be important for population regulation. Moreover, examination of different life stages revealed no differences in the gravid mussel stage or the stage when mussels infect salmonid fish. Instead, differences were observed for the juvenile, benthic stage, presumably related to differences in turbidity and sedimentation. High turbidity may affect filter-feeding efficiency of mussels and high sedimentation may reduce survival by clogging sediments, thereby altering, for example, oxygen and food conditions. In the study of the effects of turbidity, bioturbating mayflies increased turbidity and filter-feeding dreissenid mussels reduced turbidity. Mussel growth both decreased and increased with increasing turbidity, depending on sediment type.

Turbidity and sedimentation often impact entire stream systems, and a holistic, catchment-based management strategy may be needed to reduce the effects of sedimentation on freshwater pearl mussels. The effects of restoration take a long time and must start soon if recruitment of mussels is to be re-established. Restoration may also be more urgent in some streams than in others, as the maximum age of M. margaritifera populations in my study differed by as much as 60 years. As mussel and trout densities seem to be important for recruitment success, one conservation method may be to concentrate mussels into sites where trout density is high.

Using a combination of mathematical analysis, model fitting and parameter estimation, this thesis examines the dynamics and control of host-parasite systems in heterogeneous and disturbed environments. The first chapter introduces and tests models for the population dynamics of Sclerotinia minor, an economically important fungal plant parasite, and the fungal hyperparasite Sporidesmium sclerotivorum in a closed system from which any host of S. minor is excluded. Model structures are identified that reflect experimental data rather than models that are simply mathematical abstractions. Various elaborations of this simple model are discussed in the next chapter and, specifically, the effect of a latent period of infection and the influence of differentiating between primary and secondary infections are considered. In the following chapter, models are developed in which the dynamics of a host crop (lettuce) of S. minor are included. Various mechanisms that contribute to the observed persistence of the parasite are examined and, in particular, the roles played by discontinuities due to planting and harvesting of the lettuce crop, spatial heterogeneity and changes in environmental conditions are considered. Although the models discussed in the first three chapters are developed with close reference to the S. minor-S. sclerotivorum system, they are of broad applicability. In the remaining largely theoretical chapters, the population dynamics of the models are analysed, paying particular attention to thresholds for invasion and persistence. The persistence of host-parasite interactions in disturbed environments (where the host is not continuously present or does not continuously reproduce) is considered first. In the penultimate chapter, thresholds for invasion in plant-parasite systems are derived. These systems are characterised by dual sources of inoculum (primary and secondary infection) and a host response to infection load. Finally, the simple model fitted to the S. minor-S. sclerotivorum data is used to examine the effects of heterogeneous mixing on invasion and persistence.

O nível de perturbação a que um ambiente está sujeito pode afetar profundamente o processo de regeneração natural, através de modificações nas fontes de regeneração. Os principais mecanismos de regeneração natural das florestas são a chuva de sementes (dispersão), o banco de sementes do solo e o estabelecimento de plântulas. O presente estudo tem como objetivo analisar uma das principais etapas da regeneração, a chuva de sementes, em áreas de perturbações naturais (clareiras) e antrópicas (área queimada) e áreas sem indícios de perturbação recente na Mata Atlântica do sul da Bahia. Para a amostragem, foram instalados coletores de sementes em ambientes de sub-bosque, de clareiras naturais e de uma área perturbada por fogo, num total de 144 coletores de 0,50 x 0,50 m, amostrados mensalmente. A chuva de sementes da Floresta Ombrófila Densa analisada foi contínua ao longo dos dois anos amostrados, mas apresentou flutuações entre períodos do ano e variações entre os ambientes analisados. Foram amostradas 41.910 sementes, pertencentes a 198 morfoespécies, sendo que as 120 que puderam ser identificadas foram distribuídas em 31 famílias e 57 gêneros. As 78 espécies indeterminadas representam apenas 256 sementes ou 0,6% do total de sementes amostradas. A menor quantidade total de sementes nesses dois anos foi observada no ambiente de clareiras (7.555, representando 1,25 sementes/m²/dia), enquanto o maior número de sementes foi observado na área queimada (13.656, ou seja, 2,17 sementes/m²/dia). Não foram constatadas diferenças significativas entre a proporção de espécies anemocóricas para os ambientes de clareiras e sub-bosque em nenhum dos anos analisados. Os ambientes mais similares foram o sub-bosque próximo à área queimada (MP) e o subbosque adjacente às clareiras (SB), seguido pelas clareiras (C) e pelo sub-bosque próximo à área queimada (MP). Os períodos de maior taxa de deposição de sementes estiveram concentrados principalmente no meio de ano para praticamente todos os ambientes. A chuva de sementes foi dominada por um pequeno número de espécies produzindo cerca de 98% do total de sementes amostradas, e com muitas espécies sendo representadas por poucas sementes ao longo do período de estudo. Essa dominância foi representada principalmente por três espécies arbóreas pioneiras nativas: Miconia mirabilis, Cecropia pachystachya e Henriettea succosa. Em análise mais detalhada da chuva de sementes destas espécies foi observado que as espécies Miconia mirabilis e Cecropia pachystachya mostraram um padrão anual de deposição de suas sementes, sugerindo que estas espécies possuem uma fenologia definida com longos períodos de deposição de sementes durante o ano. Henriettea succosa foi a espécie que obteve uma distribuição mais homogênea entre os quatros ambientes observados, porém sua maior deposição de sementes ocorreu exclusivamente no mês de abril de 1999.
The disturbance level to which a forest is exposed to may affect its dynamics, modifying the recruits sources. The main mechanisms of forest natural regeneration is seed rain (dispersion), soil seed bank and seedlings establishment. This study aims to analyze seed rain within fire and natural (gaps) disturbed areas and sites with no sign of recent disturb at Atlantic Forests of South Bahia. Sampling was taken monthly through seed rain collectors located under gaps, understorey and fire disturbed areas, in a total of 144 0,5x0,5 m collectors. Although seed rain sampling was continuous, fluctuations were noticed for distinct seasonal periods and environments. A total of 41.910 seeds were sampled, representing 198 morfo-species; 120 were identified and classified into 31 botanical families and 57 genera. The remaining 78 morfo-species were represented by 256 seeds or 0,6% of total sampled seeds. The lower quantities of seeds were observed within gaps environments (7.555 seeds, representing 1,25 seeds/m²/day), while the higher amounts were observed for the fire disturbed areas (13.656 seeds or 2,17 seeds/m²/day). No significant differences were found regarding anemochoric species occurrence between gaps and understorey environments. Similarities were found between fire disturbed areas (MP) and their surrounding understorey environments (SB) and also between gaps (C) and understorey close to fire disturbed areas (SB). The periods of seeds deposition higher rate had been mainly concentrated in the middle of the year for practically all environments. Seed rain was characterized by few species that produced around 98% of the total amount of sampled seeds, with most of the species being represented by few seeds during this study. The dominant species were represented by three native pioneer tree species: Miconia mirabilis, Cecropia pachystachya and Henriettea succosa. A more detailed analysis of the seed rain revealed that Miconia mirabilis and Cecropia pachystachya have an annual deposition pattern, suggesting that these species have a defined phenology, with long periods of seeds deposition along a year. Henriettea succosa presented the most homogeneous distribution among the observed environments, with higher levels of deposition during April 1999. Further studies are needed to understand the observed patterns of this study, especially on M. mirabilis and C. pachystachya phenology.

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Composition and diversity of anuran amphibians in preserved and disturbed environments in the Cerrado of the State of Goiás, Mid-West Brazil. The Cerrado is the second largest biome of Brazil, with an approximate area of 2 million km², which represents about 23% of the total area of the country. Despite the high conversion of natural areas of the Cerrado in agricultural areas and pastures, comparative studies that address aspects of the composition and diversity of frogs from adjacent areas in different states of conservation are lacking. Thus, this study aimed to address taxonomic richness and community composition of anuran amphibians in twelve water bodies located in preserved areas (inside the National Park of Emas - PNE) and disturbed areas located around the PNE to test whether the structure of frogs communities is different in preserved and disturbed areas and whether species richness is correlated with descriptors of the heterogeneity of habitats. Were recorded 25 species of frogs belonging to nine genera of five families in the 12 water bodies sampled. Species richness was higher in disturbed than in preserved areas. Diversity and equitability were significantly higher in preserved water bodies (P <0.05) while dominance was higher in disturbed water bodies. An analysis of percentage of similarity (SIMPER) showed that the percentage of dissimilarity between the compared groups was 52.26%. The analysis of similarity (ANOSIM) showed significant results on differentiation between groups (Global R = 0.17, P = 0.04). Species richness was not related to any descriptor of heterogeneity. Geographic distance was related to species composition between sampled water bodies (r = -0.35, p = 0.01). At least two non-exclusive factors may be responsible for patterns of species composition and diversity of frogs found in the environments studied: a) the disturbance caused by human action in the use of natural areas for agriculture and livestock enables greater richness of species in disturbed areas, which is consistent with the hypothesis of intermediate disturbance, b) the migration between adjacent ponds allows the maintenance of communities and patterns of species composition. Thus, although species richness was lower in preserved water bodies, the highest diversity recorded in such habitats demonstrates their importance for the maintenance of community integrity and viable frogs populations
As comunidades de anfíbios anuros, inclusive em regiões tropicais, são influenciadas diretamente pelas condições ambientais, as quais desempenham um papel importante na estruturação e regulação das comunidades. Esse estudo teve como objetivo determinar a diversidade de modos reprodutivos, a temporada de vocalização e testar a correlação das variáveis climáticas com a riqueza, a abundância dos anuros adultos e dos girinos e com a atividade de vocalização dos machos em 12 corpos d‟água localizados no interior e entorno do Parque Nacional das Emas, sudoeste do Estado de Goiás, Brasil. Foram realizadas 16 amostragens entre dezembro de 2005 e março de 2008. Um total de 25 espécies de cinco famílias foram registradas: Bufonidae (1 espécie), Hylidae (9 espécies), Leptodactylidae (8 espécies), Leiuperidae (6 espécies), Microhylidae (1 espécie). Quatro padrões de atividade reprodutiva foram reconhecidos entre as espécies: contínuo, intermediário, prolongado e explosivo. A riqueza de anuros adultos, a abundância e atividade de vocalização dos machos foram positivamente relacionadas com a temperatura do ar, umidade e precipitação. A riqueza de girinos foi positivamente relacionada com a precipitação e com a temperatura da água, mas não houve relação da abundância de girinos com nenhum dos descritores climáticos. Foram registrados seis modos reprodutivos 56% das espécies apresentaram modos reprodutivos aquáticos generalizados, e 44% depositam os ovos em ninhos de espuma. As espécies registradas no presente estudo apresentaram predominância de modos reprodutivos generalizados e padrão reprodutivo tipicamente associado ao período quente e chuvoso, como esperado para regiões tropicais sazonais. Entretanto, a segregação temporal entre grupos de espécies dentro do período chuvoso parece facilitar a coexistência de espécies generalistas típicas de áreas abertas e/ou antrópicas

Methylmercury (MeHg) is the most toxic species of mercury (Hg), and is an important ecosystem contaminant. In wetlands on the Canadian Shield, in NW Ontario, MeHg concentrations in peat and peat porewater ranged from 0.3 to 53 ng $ rm g sp{-1}$ and $<$0.1 to $ rm 7.3 ng l sp{-1},$ respectively. The greatest concentrations of MeHg occurred just below the water table, emphasizing the importance of redox reactions in Hg methylation. Methylmercury partition coefficients between peat and peat porewater ranged from $1.6 times 10 sp3$ to $8.6 times 10 sp5.$ No significant correlations between MeHg and concentrations of $ rm H sp+, NH sb4 sp+, NO sb3 sp-, NO sb2 sp-,$ total dissolved nitrogen (TDN), total dissolved phosphorus (TDP), $ rm SO sb4 sp{2-},$ and dissolved organic carbon (DOC) in the porewater of the wetlands were found.
Following shallow impoundment of a wetland, MeHg concentrations in the upper metre of peat porewater increased from $ rm 0.2 pm 0.2 ng l sp{-1}$ to $ rm 0.8 pm 0.8 ng l sp{-1}.$ Total mercury (T-Hg) and MeHg concentrations were determined in decomposing sedge, spruce needles, and Sphagnum moss, placed in a headwater wetland and the impounded wetland. The amount of T-Hg decreased in all tissues regardless of location. the amount of MeHg increased by as much as an order of magnitude in the tissues placed in the impounded wetland and wet areas (hollows and lawns) of the headwater wetland, but decreased in tissue placed in the dry areas (hummocks) of the headwater wetland. Therefore, it is during anaerobic decomposition of plant material that MeHg is produced in wetlands.
Incubations of peat were performed with addition of Hg, molybdate, $ rm SO sb4 sp{2-}, S sp{2-}, NH sb4NO sb3,$ pyruvate, and upland DOC. Methylmercury production was increased only after addition of $ rm SO sb4 sp{2-}$ and retarded only by $ rm NH sb4NO sb3.$ Although $ rm SO sb4 sp{2-}$ may not be required to methylate Hg, the increased availability of $ rm SO sb4 sp{2-}$ may influence the size and composition of the population of sulfate reducing bacteria in peat, thereby increasing the potential for Hg methylation.

Landmines are one of the most prolific, human-made environmental hazards impacting the world. Although there are numerous technologies used to detect buried landmines, none enable a perfect find rate, in part, due to the heterogeneous nature of the environment in which they are buried. Variations in environmental conditions such as soil moisture and climate (e.g., temperature, diurnal fluctuations) impact detection performance. Improved understanding of the environmental conditions associated with minefield emplacement is needed to enable improvement in the algorithms used by detection technologies (e.g., infrared, ground penetrating radar), thus increasing their performance and probability of detection rates. However, there is a lack of understanding of the effect of the mine placement on the heat and mass transfer dynamics in the vicinity of the mine. More specifically, very little is known about how soil disturbance, a process that changes the soil thermal and hydraulic properties of the soil surrounding the mine, due to the placement and burial of the mine effects the soil moisture and temperature conditions in the vicinity of the mine. This is important because understanding these impacts enables increased ability to compare progressively complex models to measured aspects of interest specific to landmine emplacement conditions. The purpose of this research is to better understand the effect of soil disturbance (i.e., loosening the soil) and mixing (i.e., combining different soil types) on heat and mass transfer behavior in the vicinity of buried landmines. The aim is that this knowledge can help future research efforts to improve algorithms associated with various detection technologies. This research integrates a field experiment and numerous laboratory experiments with analytical modeling. In the first task, the thermal conductivity of mixed sands are evaluated at the small scale, providing critical knowledge of the unique behavior. Results indicate that for the test sands studied, knowledge of soil density enables identification of both saturated and dry thermal conductivity which enhances modeling of the thermal conductivity-saturation relationships. Experimental data were used to test thermal conductivity-saturation models. The analytical models varied in their ability to capture the thermal behavior, demonstrating the need for a physically based thermal conductivity-saturation model. The second task compares several approaches used to determine evaporation with several laboratory evaporation and evapotranspiration experiments in an effort to determine an appropriate method that can be applied to studies of landmine detection, specifically, disturbed soil conditions. Results demonstrate that the methods vary in their ability to capture atmospheric versus diffusion dominated evaporative stages for the test soils and boundary conditions studied. Although no one method is applicable for all boundary and initial conditions, the sensible heat balance and heat pulse method enabled the highest level of agreement between measured and modeled evaporation from bare soil experiments. Additionally, the ability of this method to isolate evaporation under evapotranspiration conditions has the potential to isolate transpiration which is significant for many agricultural applications as well as modeling efforts. The third task investigates the impact of soil disturbance and mixing on heat and mass transfer behavior under varying climate conditions at the laboratory scale. Using the methods established in Task 2, I could quantitatively understand the evaporation rates from soils under different conditions (e.g. disturbed or loose conditions compared to undisturbed or tight conditions) using both in-situ and remotely sensed temperature and soil moisture data. Results demonstrate that the disturbance and mixing cause a significant increase in evaporation compared to undisturbed soil conditions. Under disturbed conditions without mixing, the increase evaporation occurred in part to due capillary pumping from the loose soil into the tight soil. Additionally, higher evaporation rates were observed from the upstream tight region compared to the downstream tight region. Finally, the fourth task is a field scale proof of concept demonstration. The purpose of this task is to obtain a data set that includes aspects of tasks 1-3, thus testing our understanding of soil disturbance at the field scale. Experimental results demonstrate distinct behaviors in soil moisture and temperature distributions above and around buried objects that change with climate forcings (i.e., temperature and rain events).

Master of Science
Department of Biological & Agricultural Engineering
Ronaldo G. Maghirang
Military training lands can be significant sources of fugitive dust emissions due to wind erosion. This study was conducted to determine dust emission potential of soils due to wind erosion as affected by off-road military vehicle disturbance. Multi-pass traffic experiments using two types of vehicles (i.e., wheeled and tracked) were conducted on six soil textures at four military training facilities: Fort Riley, KS; Fort Benning, GA; Yakima Training Center, WA; and White Sands Missile Range (WSMR), NM. Prior to and after the preselected number of vehicle passes, soil samples at three locations were collected with minimum disturbance into trays. Adjacent to the location where tray samples were collected, a Portable In-Situ Wind Erosion Lab (PI-SWERL) was used to measure dust emission potential. The tray samples were tested in a laboratory wind tunnel (with sand abrader) for dust emission potential using a GRIMM aerosol spectrometer and gravimetric method with filters. Comparison of the PI-SWERL (with DustTrak™ dust monitor) and wind tunnel (with GRIMM aerosol spectrometer) measurement results showed significant difference in measured values but high correlation, particularly for soils with high sand content. Wind tunnel tests results showed that sampling locations significantly affected dust emissions for the tracked vehicles but not for the light-wheeled and heavy-wheeled vehicles. Also, soil texture, number of vehicle passes, and vehicle type significantly affected dust emissions. For the light-wheeled vehicles, dust emissions increased as the number of vehicle passes increased. From undisturbed conditions to 10 vehicle passes, there was a significant (P<0.05) increase in dust emissions (297%) on average for all light-wheeled vehicle tests. From 10 to 25 passes and 25 to 50 passes, an additional 52% and 62% increments were observed. For the tracked vehicle, for the straight section sampling location, dust emission increased as the number of vehicle passes increased. However, for the curve section, dust emissions at any level of pass were significantly higher than initial condition; beyond the first pass, no significant increase was observed.

The conservation of biological diversity has become one of the most important goals of managing forests in an ecologically sustainable way. In this thesis, I report a comprehensive study designed to examine the long-term effects of commercial logging and high-intensity fire, and the ability of Population Viability Analysis (PVA) models to predict these effects to aid in the conservation and management of multiple species. Initially, I compared the abundance of small mammals (A. agilis, R. fuscipes, A. swainsonii), and lizards (L. delicata, L. guichenoti, E. heatwolei), in sites with different disturbance histories: 18-19 yearold logging regrowth, 28-29 or 33-34 year???old clearfelling regrowth and unlogged forest. All sites had previously been burnt by bushfires. No evidence of long-term effects of logging or fire was found for A. agilis, R. fuscipes, L. delicata or L. guichenoti, and there were not enough data to make conclusions for A. swainsonii and E. heatwolei. Then the effects of a hazard-reduction burn were investigated. There was variation between the species in the effects of the burn, with interactions between year, aspect and burning for A. agilis and R. fuscipes, and interactions between year, disturbance and topography for the Lampropholis species. A. swainsonii became extremely scarce in the forest after the burn and E. heatwolei were generally unaffected. Next, PVA metapopulation models were used to predict the likely abundance and patch occupancy of these species based on historical data. Retrospective testing showed the models were accurate for all species, but best for A. agilis and R. fuscipes. Lastly, PVA modelling was used to rank management options; no management action, a hazard-reduction burn in 2005 or a logging event in 2005. The models predicted that future management is likely to result in the extinction of A. agilis, R. fuscipes and L. guichenoti by 2010. However, no one management scenario was most detrimental to all species. The current management regime for this forest involves commercial logging on a 40-year cycle and regular hazard-reduction burning. PVA modelling predicts that A. swainsonii and L. delicata are at the greatest risk of extinction under this regime, but that it is also likely to lead to the extinction of A. agilis, R. fuscipes and L. guichenoti in the near future. The results of this research indicate that the conservation of multiple species under one management regime is unlikely to be successful.

This study examined the effects of seedbed and seedling environment on establishment of early and late seral dominant alpine species. Species studied included late seral dominant forbs (Geum rossii, Artemisia scopulorum, and Polemonium viscosum), early seral dominant forbs (Potentilla diversifolia and Sibbaldia procumbens), a late seral dominant grass (Festuca idahoensis), and early seral dominant grasses (Calamagrostis purpurascens and Deschampsia cespitosa). Germination responses of each species to wet vs. dry cold stratification and light vs. dark conditions were investigated. No statistical differences were observed in the seed germination of early and late seral dominant forbs or early and late seral dominant grasses, but significant differences were observed in the responses of grasses and forbs. Seed germination of forbs was greater under light than dark conditions and following wet cold storage. Effects of fertilization on growth responses and nutrient uptake of G. rossii and D. cespitosawere evaluated in a factorial greenhouse experiment in which seedlings of each species were grown at four levels of nitrogen (N) and phosphorous (P). The late seral dominant forb responded more like a species from a low-nutrient environment exhibiting lower relative growth rates, higher root:shoot ratios, and a smaller response to N than the early seral dominant. A field experiment on the Beartooth Plateau, Montana, examined the soil environment and seedling emergence, growth, and survival of seeded early and late seral dominants on loamy sand soils of a severe disturbance and on peat soils of an undisturbed area during two growing seasons. Effects of fertilizer and mulch were examined on the severely disturbed area. Differences between uncleared turf and turf cleared of vegetation (gap disturbance) were evaluated on the undisturbed area. The gap disturbance had higher levels of N and P and warmer soil than the severe disturbance or vegetated undisturbed area. Soil water potentials were never low enough to result in plant stress. Seedling growth was slow - .005 g to .04 g dry weight the first growing season and .02 g to .20 g the second growing season. Growth was greatest on the gap disturbance and on fertilized plots of the severely disturbed area. Early seral dominants had the largest seedlings and the smallest R/R+S ratios. Mortality was low - odds of .50 were rarely exceeded even after two years. Survival was higher on warm, nutrient rich soils of the gap disturbance. Mulch increased emergence and survival on the severe disturbance. Fertilization increased mortality, probably because an initial pulse of N was followed by a rapid decline. Higher mortality occurred in 1986 than 1985 as 1986 had a shorter growing season and cooler air and soil temperatures early in the growing season.

Geological disposal of radioactive wastes currently stored at Earth's surface is now the favoured management pathway for these materials. Typically, intermediate level wastes (ILW) are grouted and emplaced in a geological disposal facility (GDF) which will be backfilled, possibly with cementitious materials. Post-closure leaching of the cementitious materials in a GDF is expected to create hyperalkaline conditions in and around the repository, resulting in mineral alteration and crystallisation, both within the engineered barrier and host rock; creating a persistent chemically disturbed zone (CDZ). Iron derived from within the host rock as a result of alkaline breakdown of Fe-bearing silicate minerals (e.g. biotite, chlorite); corrosion products formed within the repository; or iron contained within the waste; will form secondary iron (oxyhydr)oxide minerals. The formation and re-crystallisation of these reactive mineral phases may sequester radionuclides through a host of processes: surface-mediated reduction to less soluble forms; adsorption onto, and/or incorporation into stable secondary or tertiary iron oxide phases. Therefore iron (oxyhydr)oxides will be key to the fate of radionuclides potentially released from within radioactive wastes disposed of in a GDF.In this study, the fate of U(VI) and Tc(VII) was considered during crystallisation of ferrihydrite to more stable iron oxide phases (e.g. hematite and magnetite) and, in three synthetic cement leachates (pH 13.1, 12.5, 10.5) designed to reflect the early-, middle- and late-stage evolution of the CDZ. XRD and SEM/TEM have been used to characterise the mineralogy during crystallisation. Partitioning of U(VI) and Tc(VII) between the solid and solution has been followed throughout, with chemical extractions used to determine the distribution of the radionuclides adsorbed to, and incorporated within the solid. Synchrotron-based XAS techniques have been utilised to probe the oxidation state and molecular scale bonding environment of the radionuclides associated with the solids. The data suggest that: U(VI) is incorporated into the hematite structure in place of Fe(III), in a distorted octahedral environment with elongation of the uranyl bond; Tc(VII) is reduced to Tc(IV) and incorporated into the octahedral site within the magnetite structure in place of Fe(III), and is retained in the same environment even after extensive oxidation of the magnetite to maghemite; and that U(VI) may also be incorporated as U(V) or U(VI) into the magnetite structure, with similar recalcitrant behaviour during oxidation. These results highlight the importance of mineral reactions within the CDZ as potentially significant pathways for immobilising radionuclides released from a GDF.

This study investigated the transplantation of understory plants within the Cu-Ni smelterdamaged urban forest of Sudbury, Ontario, Canada, to increase plant biodiversity in an area where natural colonization of understory species is delayed. The goal of my study was to evaluate establishment of 16 m2 vegetation mats along a gradient of smelter disturbance and to relate successful establishment to abiotic and biotic site characteristics. Specific investigations were conducted to determine whether soil quality influenced root growth and transplant establishment. Variables associated with smelter emissions and soil temperature were the best predictors of successful transplant establishment of understory plant species, but relationships were species specific. Also, root growth was not limited to organic soils of the transplant mat and roots were able to grow into receptor site soil. Knowledge of environmental factors influencing establishment will help to determine site locations and to select species to introduce when transplanting understory species in future reclamation projects.

A recuperação ambiental de áreas exploradas pela mineração de areia na região do Vale do Paraíba, Estado de São Paulo, constitui anseio popular, obrigação constitucional e fator de diferenciação dentro da mais moderna visão empresarial. Este trabalho estuda a aplicação de turfa como um melhorador de solos na etapa final do processo de recuperação destas áreas: o restabelecimento da vegetação nativa. O interesse surgiu da experiência de trabalho do autor com pesquisa mineral e tecnológica desta substância, além da observação e acompanhamento de alguns projetos de revegetação nestas áreas, tidas como ambientalmente sensíveis e onde os solos apresentam-se, via de regra, improdutivos; sua utilização representou, nestes casos, a diferença entre o sucesso e a necessidade de replantio. Apresenta-se uma revisão bibliográfica sobre turfa e suas propriedades agronômicas, bem como acerca da utilização de matéria orgânica na revegetação de áreas degradadas. O estudo constituiu um comparativo entre resultados de ensaios efetuados em amostras de solo provenientes de área abandonada pela mineração de areia, homogeneizadas em laboratório em seu estado original (branco), de um lado, e com adição de turfa em diferentes proporções, de outro, visando aferir se alguma delas poderia adequar-se mais satisfatoriamente à melhoria das condições gerais do solo em questão. Foram analisadas variações em propriedades químicas e físicas como retenção de cátions, efeito tampão, densidade aparente, condutividade hidráulica e porosidade. Abre-se a possibilidade de os resultados deste projeto não se limitarem apenas à Indústria Mineral mas estenderem-se a outros setores onde haja a necessidade de recuperação de solos, fornecendo subsídios a eventuais modificações no manejo de solos agricultáveis, com perspectivas de geração de economia de recursos em irrigação, fertilizantes e defensivos agrícolas.
The environmental recuperation of areas explored by sand mining in the Vale do Paraíba region, in the State of São Paulo, is a popular aspiration, a constitutional obligation and constitutes a differentiating factor in the visions of modern enterprise. This work studies the utilization of peat as a soil conditioner in the final stage of the recuperation process for these areas: the revival of indigenous vegetation. This idea arose from the author's experience in technological and mineral research into peat, coupled with the observation and monitoring of these environmentally sensitive areas, whose soils were, from an agricultural stance, generally unproductive. The utilization of peat, in these cases, represented the difference between success and the necessity for a replantation process. This study presents a review of the agronomic properties of peat as well as the application of organic matter in the revegetation of damaged land. It is a comparative study between laboratory assay results from soil samples in their original state, and those where the soil has variable peat contents, seeking to ascertain which, if any, results in better general conditions for that particular soil. Both physical and chemical properties were analyzed, with an emphasis on cation exchange capacity, buffering, bulk density, hydraulic conductivity and porosity. There is a possibility that the results of this project can extended beyond the Mineral Industry to other sectors, where there are needs for soil recuperation, leading to cost savings for irrigation, fertilizers and agrotoxic compounds in food production areas.

SCOPO: Revisione basata sulle evidenze per indagare il ruolo del gioco all’interno dell’intervento precoce dei bambini a rischio di disturbo neuromotorio ed evidenziare i concetti su cui basare e guidare il gioco spontaneo del bambino. METODO: Sono state consultate le banche dati Chinal, Cochrane e PubMED. Sono stati selezionati studi in lingua italiana, pubblicati dal 2014, effettuati su bambini da 0 a 2 anni, classificati ad alto rischio di disturbo neuromotorio e riguardanti interventi precoci basati sul gioco. RISULTATI: Sono stati rilevati 49 studi, di cui 3 corrispondono ai criteri di inclusione. La qualità della metodologia è stata valutata tramite la scala PEDro, poiché sono tutti studi primari. Gli studi valutano l’efficacia di tre differenti metodiche di intervento precoce (SPEEDI, CareToy, GAME) accumunate da caratteristiche, come il coinvolgimento famigliare, la personalizzazione del trattamento, l’obiettivo specifico, l’arricchimento ambientale e sono tutti e tre interventi concentrati sul gioco. CONCLUSIONE: Gli studi hanno evidenziato che l’intervento precoce basato sul gioco personalizzato e individualizzato, in cui è presente il coinvolgimento famigliare, che viene adeguatamente educato a proporre le giuste sfide al bambino, l’arricchimento ambientale e il trattamento orientato all’obiettivo specifico influiscono positivamente sullo sviluppo motorio del bambino, favorendo la progressione delle sue capacità motorie. La limitazione degli studi, oltre che alla scarsa quantità di studi trovati, è la mancata specificità degli elementi di ogni intervento per poter verificare i benefici dimostrati. Tuttavia future ricerche devono approfondire il tema del gioco per poter fornire indicazioni più precise ai fisioterapisti.

Die vorliegende Arbeit hatte zum Ziel, das Auftreten von Milchejektionsstörungen in Produktionsherden zu erfassen und deren Ursachen zu finden. Die Fragestellung wurde in fünf methodisch sehr unterschiedlichen Untersuchungsblöcken bearbeitet, die tierindividuelle Aufzeichnungen zu Kalbung und Verlauf des Einmelkens, Verhaltensbeobachtungen im Vorabkalbezeitraum und Messungen psychophysiologischer Parameter (Herzfrequenz, Elektromyogramm, Hautpotential und Hautwiderstand) während eines Tests auf Stressstabilität sowie während des Einmelkens beinhalteten. Es nahmen 9 sächsische Betriebe an der Untersuchung teil. Die Datenerfassung erfolgte über einen Zeitraum von 20 Monaten in den Jahren 2004 / 2005. Es konnten die Daten von 1767 Färsen erfasst werden. Es wurden eindeutige Zusammenhänge zwischen dem durch suboptimale Haltungsbedingungen verursachten Wirken sozialer Stressoren in der Tiergruppe und dem Auftreten von MES gefunden. Demnach trat MES verstärkt in Betrieben auf, in denen bereits im Vorfeld der Kalbung eine chronische Stresssituation für die Tiere bestand. Hierbei konnten bei gemischten Färsen – Kuh- Gruppen die Anwesenheit der Altkühe und bei reinen Färsengruppen das zu geringe Platzangebot im Laufbereich als Hauptursache gefunden werden. Die Umstände von Abkalbung und Einmelken sind in den untersuchten Betrieben nicht primäre Ursache von MES, können aber verstärkend oder mildernd wirken. So bewirken Umstallungen kurz vor dem Abkalbetermin, eine langer Verbleib des Kalbes an der Kuh, zu kurze Pausen zwischen der Kalbung und der ersten Melkung sowie gesundheitliche Beschwerden im peripartalen Zeitraum ein Ansteigen des MES-Risikos. Betroffen sind hierbei vor allem stresslabile und rangniedrige Tiere sowie Tiere, die unter Testbedingungen bevorzugt introvertierte Verhaltensweisen (ängstlich, demütig) zeigten. Es bestand kein Unterschied hinsichtlich der Stressstabilität der Herden zwischen den Betrieben. Während des Einmelkens unterschieden sich Tiere mit und ohne MES in ihrem Verhalten und den gemessenen Parametern kaum von einander. Tiere mit MES zeigen lediglich eine verstärkte Neigung zu Überreaktionen und eingeschränkter Reaktionsfähigkeit bei den elektrodermalen Parametern, wobei die Differenzen häufig nicht statistisch zu sichern waren. Es konnte keine genetische Veranlagung zur Ausbildung einer MES nachgewiesen werden. Die errechnete Heritabilität lag bei h² = 0,009. MES ist somit als ein betriebsspezifisches Problem zu bezeichnen, das in den hier untersuchten Betrieben vor allem haltungsbedingte Ursachen hat.
The present study was designed to describe the occurrence and determine the causes of disturbed milk ejection (= MES = Milchejektionsstörung) in production herds. The question was treated in an examination with five parts with difficult methods: record individually courses of calving and the first milkings, observe the behaviour in the last weeks before the calving, measure psychophysiological parameters (heartrate, elektromyogram, skin conduction and electrical skin resistance) during a test of stress sensitivity and during the first milkings and an genetic analysis. Nine saxonian herds were involved. The data record was for 20 months in the years 2004 / 2005 and cover 1767 heifers. We found clear connections between social strains, they work in the groups of animals and was caused through suboptimal environment, and the occurrence of MES. We found more MES in herds, where animals had a chronical stress situation in the last weeks bevor the calving. The most important stressors are the presence of multiparous cows in mixed groups with cows and heifers and the lack of room for motion in the box when heifers are alone. The circumstances of calving and the first milkings are not the primary causes of MES in this study, but they can influence this problem. So we found an increase of risk for MES, when 1. the time between the transport of animals in the calving box and the calving was too short, 2. the calf stayed with the cow, 3. the time between the calving and the first milking was too short 4. the animal has health problems in the time around the calving. The animals with the highest risk for MES have low stress resistance are unstable for stress, have a low range in the herd and showed an introverted behaviour (timid, humble) in the test. There was no difference in the stress sensitivity between the herds. During the first milkings we found just little differents at behaviour and at measured parameters between animals with and without MES. Animals with MES showed a small disposition to overreactions or to restrict the ability of reaction in elektrodermal parameters, but the differences are often not significant. We couldn´t found genetic causes of MES. The heritability was h² = 0,009. In conclusion, MES is an herd specific problem. In the herds that were examine, the important causes of MES are suboptimale environment and management of the groups of animals.

Efforts are increasing to mitigate pressures on wetlands from human disturbance. Conservation of these systems requires expansive knowledge of ecosystem structure and underlying environmental gradients exerting control over plant distribution. A multitude of environmental gradients important in undisturbed wetland systems have been studied extensively. The most important have been shown to be: acidity/base richness, nutrient status, water level fluctuations, and organic matter accumulation (Bridgham et al., 1996). Human modification of wetland hydrology may alter the relationships between species distribution and underlying environmental gradients. It is therefore important to study the plant-environment relations in disturbed systems to collect baseline data and subsequently monitor changes in the system. The primary aim of this thesis was to examine which environmental gradients were important in the distribution of wetland species in a disturbed stream fen/mound bog system. The study area, Blaney bog, is a wetland that has been modified by the construction of a dyke/canal system dividing the area into two separate sections. Aerial photographs and primary survey showed that four plant community types dominate the Blaney bog landscape: Kalmia occidentalis, Phalaris arundinacea, Spiraea douglasii, and Carex spp.. In accordance with the primary aim, a dipwell network was established in the four plant community types. Soil water was sampled from the dipwells for a ten month period, peat cores were collected and the vegetation was surveyed at each site. In addition to the initial 16 dipwell sites, 22 sites were added to the study. At these additional sites the same vegetation and soil data was collected however because the sites lacked dipwells, the water was sampled only once. Data analyses addressed the inter-relations between the water and soil variables and plant community composition. Non-parametric analyses of, variance were used to examine if the differences between plant community groups were significant. Spearman's correlation coefficients were calculated to examine relationships between environmental variables. All variables were also analyzed simultaneously using the Nonmetric Multidimensional Scaling method. Results showed that the Kalmia sites were the most representative of poor fen sites. Sites in the other three plant communities varied in their chemistry compared to the expected range found in undisturbed fens. Water components were much more variable than the soil components. The bog-fen gradient was clearer in the pH values, cation concentrations and nutrient status in the soil compared to unclear patterns in the water data. Although total soil nutrient concentrations may not be reflective of nutrient availability, overall the soil components are much more static and present a clearer picture of site conditions at Blaney bog. The disturbance caused by the dyke/canal system and possibly ongoing influx of drainage waters from neighboring agricultural land, are thought to substantially affect the hydrology of this wetland. Effectively, the water table and chemistry are much more dynamic than in undisturbed wetland systems. This study recommends that future monitoring Blaney bog should focus on the soil component rather than the water component and should further investigate the effect of water table fluctuations on plant distribution.

Invasive alien plants in South Africa have become one of the major environmental problems affecting millions of hectares of productive and conservation land. Acacia mearnsii, black wattle, is a key invader species along the eastern escarpment. The major rivers of the country rise on this escarpment and the water catchments have been severely affected by black wattle invasion that has reduced water flow and increased soil erosion. The government introduced the Working For Water (WFW) programme in 1995 in order to address the problem of invasive alien plants in the country while, at the same time, creating job opportunities. This study researches the implementation of WFW projects in the small mountain village of Hogsback in the Amatola Mountains since their inception in 1996/97. The main research question posed by this study is: "What factors support or threaten sustainable environmental management through the Working For Water Programme in the Hogsback area?" It gives a history of the environmental changes since 1800 as a result of human disturbance. The social history of the area is described from the viewpoint of the social and cultural disturbances that led to the present day community conflict. The interface between the environmental and social history is then discussed. Semi-structured interviews were held with twenty eight members of the Hogsback community to solicit their views and perceptions of the WFW projects and the role of civil society and government in sustainable environmental management of invasive alien vegetation. Environmental and development plans undertaken for the Hogsback area were analysed. The results were then discussed in terms of the national and regional goals of WFW. The findings indicated that most of the goals of WFW have not met with great success in Hogsback. A number of limiting factors were identified, the primary one being community conflict, both within and without WFW. As the community struggles to address the aspirations of the landless and economically deprived black population while, at the same time, addressing the fears of the white population, the rapid rate of societal, governance and legislative change since the election of the democratic government in 1994 contributed to an environment of uncertainty. Within WFW, there are management problems that have limited the success achieved in clearing invasive alien species in the catchment. The lack of long-term strategic plans, sufficient accurate data and hands-on management are shortcomings in the local projects. The likely long-term effects of large scale clearing in this disturbed environment, without proper rehabilitation, are serious concerns.
Thesis (M.Env.Dev.)-University of Natal, Pietermaritzburg, 1999.

碩士
國立中興大學
水土保持學類
84
Study on the Adaptive Responses of Pioneer Tree Speciesat Disturbed Land to Main Environmental StressesABSTRACTTwo dominant plants, Formosan alder and Roxborgh Sumac are usually found in disturbed lands, were chosen to test their physiologocal responses under certain environmental stresses. Photosynthetic gas exchange, activity index of drought and root- moving disturbance were conducted to understand the responses of tested plants. The results obtained were as followed:1. Effects of drought acclimation on photosynthetic characteristics(1)After drought acclimation treatment, the light saturation point of Roxburgh Sumac showed a little higher than that of Formosan alder. The optimum temperature were 30℃∼35℃ for Formosan alder and 35℃for Roxburgh Sumac under drought acclimation, while in the lower temperature, Formosan alder has a higher relative net photosynthetic rate . This implied that Formosan alder is more suitable to grow in low temperature condition.(2) Tseted plants except Formosan alder without drought acclication, have a higher water ues efficiency at the light intensity of 400μmol m-2s-1. Water use efficiency in both plants were increasing with the decreasing temperature under the experiment condition.2. Short-term water withholding treatment(1)The stomatal responses of Formosan alder was more sensitive than that of Roxburgh Sumac especially for the plants without acclicated treatment. Roxburgh Sumac and acclimated plants can be expected to be as drought resitant plants due to higher photosynthetic ability under high water stress.(2)During water withholding process, the Ci/Ca ratio were 0.78-0.59 for Formosan alder, and 0.72-0.58 for Roxburgh Sumac under drought acclication.And the Ci/Ca ratio was 0.65-0.68 for Formosan alder, and 0.67-0.69 for Roxburgh Sumac under non-acclimated treatment. The leaf chlorophyll fluorescence (Fv/Fm) of acclimated plants were decreased during water withholding process except the plants without acclicated treatment. The actually responses of chlorophyll fluorescence and photosynthetic rate for different plants had to be studied further.3.The treatment of external disturbanceThe recovery capacity of the Formosan alder is better than Roxburgh Sumac due to the performance of photosynthetic rate following external disturbance. In this experiment, the photosynthetic rates of Formosan alder were 76.6∼86.8%, and 71.4∼82.1% Roxburgh Sumac comparing with check treatment.