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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Comunidades de fungos em folhedo da Mata Atl?ntica na regi?o semi?rida do Brasil

Costa, Loise Araujo 29 August 2014 (has links)
Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-01-21T00:37:49Z No. of bitstreams: 1 TESE_Loise Araujo Costa.pdf: 3490024 bytes, checksum: d67e88fa9cf7de3c8ca53e0ee35cc012 (MD5) / Made available in DSpace on 2016-01-21T00:37:49Z (GMT). No. of bitstreams: 1 TESE_Loise Araujo Costa.pdf: 3490024 bytes, checksum: d67e88fa9cf7de3c8ca53e0ee35cc012 (MD5) Previous issue date: 2014-08-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The Atlantic Forest has the highest biodiversity among tropical forests is one of the 34 priority areas for global conservation. Currently remains about 11% of its original area, which is composed of fragmented and geographically distant remnants. Among the microorganisms that compose forest ecosystems, fungi are important components because ensure the cycling of carbon and nutrients, however are poorly studied. The present study aimed to assess the diversity and distribution of fungi associated to leaf litter from three Atlantic Forest remnants in the semiarid region of Brazil: Brejo Paraibano-PB, Serra da Ibiapaba-CE and Serra da Jib?ia-BA; and the effects of methodological aspects on mycobiota. Two expeditions were conducted in each area, during the wet season and the other in the dry season, between June/2011 and January/2013. Twenty-three samples of leaf litter, five Clusia nemorosa G. Mey and eighteen Vismia guianensis (Aubl) Choisy, were collected and submitted to the technique of particle filtration. The total volume of 9.3 mL of particle suspension was plated on two different culture media: dichloran rose bengal chloramphenicol agar (DRBC) and malt yeast extract agar (MYE). The analysis of this material yielded 6.460 colonies identified 168 taxa for which data were divided into three chapters. The first chapter evaluates the effects of time (fresh material, 07, 14, 21 and 28 d) and storage temperature (room temperature and 4?C) of the leaves of C. nemorosa plus the use of two culture media on mycobiota. Analysis of covariance indicated that the richness and the number of isolates decreased with storage, however in relation to the culture medium there was no significant difference. The storage temperature had no significant influence on the community according to the t-test. The second chapter compared the communities of fungi of C. nemorosa and V. guianensis during the wet and dry seasons. Clusia nemorosa showed higher species richness and diversity of fungi compared to V. guianensis. Similarity analysis indicated that variations in the community between plants and seasons were significant while the cluster analysis and multivariate NMDS showed seasonality factor as more decisive for the distribution of fungi. The third chapter investigated the spatial and temporal distribution of fungi associated with leaf litter community of V. guianensis present in the three remaining. Multivariate analysis NMDS revealed differences in community composition of fungi in each area and climate season and the similarity analysis indicated that the differences were statistically significant. The results of this study presented a great diversity associated with the leaf litter present in remnants of Atlantic Forest and indicate that the distribution of fungi in the environment is not random. Knowledge of the effects of biotic and abiotic factors on the distribution of saprobic fungi is fundamental to understanding the role that they play in forest ecosystems. / A Mata Atl?ntica apresenta uma das maiores biodiversidade dentre as florestas tropicais sendo uma das 34 ?reas priorit?rias para a conserva??o mundial. Atualmente resta cerca de 11% da sua ?rea original, que ? composto por remanescentes fragmentados e distantes geograficamente. Dentre os micro-organismos que comp?em os ecossistemas florestais, os fungos s?o componentes importantes, pois promovem a ciclagem de carbono e nutrientes, no entanto, s?o pouco estudados. O presente estudo teve como objetivo avaliar a diversidade e distribui??o de fungos associados ao folhedo de tr?s remanescentes de Mata Atl?ntica na regi?o semi?rida do Brasil: Brejo Paraibano-PB, Serra da Ibiapaba-CE e Serra da Jib?ia-BA; bem como os efeitos de aspectos metodol?gicos sobre a micobiota. Duas expedi??es foram realizadas em cada ?rea, uma durante a esta??o chuvosa e a outra na esta??o seca, entre junho/2011 e janeiro/2013. Vinte e tr?s amostras de folhas da serapilheira, cinco de Clusia nemorosa G. Mey e dezoito de Vismia guianensis (Aubl) Choisy, foram coletadas e submetidas ? t?cnica de filtra??o de part?culas. O volume total de 9.3 mL de suspens?o de part?culas foi plaqueado em dois meios de cultivo: ?gar dicloran rosa bengala cloranfenicol (DRBC) e ?gar extrato de malte e levedura (MYE). A partir da an?lise desse material, 6.460 col?nias foram isoladas e identificadas em 168 t?xons cujos dados foram distribu?dos em tr?s cap?tulos. O primeiro cap?tulo avaliou os efeitos do tempo (material fresco, 07, 14, 21 e 28 dias) e temperatura (ambiente e 4?C) no acondicionamento das folhas de C. nemorosa al?m do uso dos dois meios de cultura sobre a micobiota. A an?lise de covari?ncia indicou que a riqueza e o n?mero de isolados diminu?ram com o tempo de acondicionamento, entretanto em rela??o ao meio de cultura n?o houve diferen?a significativa. A temperatura de acondicionamento n?o apresentou influ?ncia significativa sobre a comunidade, segundo o teste-t. O segundo cap?tulo comparou as comunidades de fungos de C. nemorosa e V. guianensis durante as esta??es chuvosa e seca. Clusia nemorosa apresentou maior riqueza de esp?cies e diversidade de fungos comparada a V. guianensis. A an?lise de similaridade indicou que as varia??es na comunidade entre as plantas e esta??es foram significativas, enquanto que a an?lise de agrupamento e a multivariada NMDS apresentaram a sazonalidade como fator determinante para a distribui??o dos fungos. O terceiro cap?tulo investigou a distribui??o espacial e temporal da comunidade de fungos associada ao folhedo de V. guianensis presentes nos tr?s remanescentes. A an?lise multivariada NMDS revelou diferen?as na composi??o das comunidades de fungos em cada ?rea e esta??o clim?tica e a an?lise de similaridade indicou que as diferen?as encontradas foram estatisticamente significativas. Os resultados deste estudo apresentam uma grande diversidade de fungos associada ao folhedo presente nos remanescentes de Mata Atl?ntica e indicam que a distribui??o dos fungos no ambiente n?o ? aleat?ria. O conhecimento dos efeitos dos fatores bi?ticos e abi?ticos sobre a distribui??o dos fungos sapr?bios ? fundamental para entender o papel que desempenham nos ecossistemas florestais.
292

EFFECT OF BEDDING TYPE AND SOIL INCORPORATION ON NITROGEN MINERALIZATION RATE OF BROILER LITTER AMENDED SOILS

Fitzgerald, Lydia A. 01 January 2019 (has links)
Broiler litter (BL) is a high value manure available to Kentucky crop producers to utilize as a fertilizer. The rate of BL application, timing of application, and method of application are all important factors to take into account when utilizing BL. A laboratory incubation was conducted to observe nitrogen (N) mineralization rates of BL amended soils over time under different conditions. Different application methods, application rates, watering frequencies, and bedding materials were used to determine their influence on N mineralization. Broiler litter applied on the soil surface, at lower rates, at lower watering frequency resulted in lower mineralization rates than BL that was incorporated, at higher rates and higher watering frequency. The rice hull bedding BL treatments had a significantly higher initial amount of NH4+-N than the wood-based bedding materials. The increased NH4+-N content produced a lower pH due to higher rates of nitrification. The difference in NH4+-N resulted in the rice hull BL treatments containing more inorganic N throughout the incubation. The wood-based BL contained significantly more carbon (C), zinc (Zn), and potassium (K). The results collected will help improve current nutrient recommendations and provide information that will help utilize BL more efficiently and economically.
293

Plastics Derived From Derelict Fishing Gear in the Arctic: Looking at Sustainable Fisheries for a Strategy of Mitigation, Remediation and Prevention in Iceland and Alaska

Armstrong, Natalie S. 01 January 2020 (has links)
Marine plastics are not just a problem, they are a silent, sinister epidemic. Marine plastics are the largest economic and ecological threat to our marine ecosystems, particularly marine plastics derived from lost and or discarded fishing gear, which affects sensitive marine communities, the chemical composition of the ocean water, and the physical makeup of the seafloor. With 6.4 million tons of marine debris entering our oceans annually, a third of which is lost fishing gear, it is estimated that, by weight, in 2050 there will be an accumulation of more plastic than fish in the ocean (Heath, 2018; Wilcox, 2015). Marine litter derived from plastic fishing gear, primarily passive gear, when lost in the ocean causes a series of consequences to the marine ecosystem, that of which increases when there are high concentrations of fishing activity in the geographic area. Arctic countries have some of the most abundant fisheries, that of which is projected to increase due to anthropogenic climate change. In the context of climate change affecting the Arctic ecosystem, in this thesis, we will review the consequences of plastics derived from fishing gear for the Arctic marine ecosystem, estimate the potential influx of derelict gear plastics originating from data obtained in Alaska and Iceland, and then confidently present effective forms of remediation, prevention, and mitigation strategized from models of sustainable fisheries to resolve the ramifications of lost and or discarded gear in Arctic communities.
294

The Influence of Solar Radiation, Temperature, Humidity and Water-Vapor Sorption on Microbial Degradation of Leaf Litter in the Sonoran Desert

January 2020 (has links)
abstract: Decay of plant litter represents an enormous pathway for carbon (C) into the atmosphere but our understanding of the mechanisms driving this process is particularly limited in drylands. While microbes are a dominant driver of litter decay in most ecosystems, their significance in drylands is not well understood and abiotic drivers such as photodegradation are commonly perceived to be more important. I assessed the significance of microbes to the decay of plant litter in the Sonoran Desert. I found that the variation in decay among 16 leaf litter types was correlated with microbial respiration rates (i.e. CO2 emission) from litter, and rates were strongly correlated with water-vapor sorption rates of litter. Water-vapor sorption during high-humidity periods activates microbes and subsequent respiration appears to be a significant decay mechanism. I also found that exposure to sunlight accelerated litter decay (i.e. photodegradation) and enhanced subsequent respiration rates of litter. The abundance of bacteria (but not fungi) on the surface of litter exposed to sunlight was strongly correlated with respiration rates, as well as litter decay, implying that exposure to sunlight facilitated activity of surface bacteria which were responsible for faster decay. I also assessed the response of respiration to temperature and moisture content (MC) of litter, as well as the relationship between relative humidity and MC. There was a peak in respiration rates between 35-40oC, and, unexpectedly, rates increased from 55 to 70oC with the highest peak at 70oC, suggesting the presence of thermophilic microbes or heat-tolerant enzymes. Respiration rates increased exponentially with MC, and MC was strongly correlated with relative humidity. I used these relationships, along with litter microclimate and C loss data to estimate the contribution of this pathway to litter C loss over 34 months. Respiration was responsible for 24% of the total C lost from litter – this represents a substantial pathway for C loss, over twice as large as the combination of thermal and photochemical abiotic emission. My findings elucidate two mechanisms that explain why microbial drivers were more significant than commonly assumed: activation of microbes via water-vapor sorption and high respiration rates at high temperatures. / Dissertation/Thesis / Doctoral Dissertation Biology 2020
295

UTILIZING PHOSPHORUS BUDGETS AND ISOTOPIC TRACERS TO EVALUATE PHOSPHORUS FATE IN SOILS WITH LONG TERM POULTRY LITTER APPLICATION

Janae H Bos (9153470) 24 July 2020 (has links)
<p>Converting a nutrient management plan from commercial fertilizers to poultry litter helps effectively utilize waste from the nearly 10 billion broiler birds across the United States. Nine field scale watersheds from the USDA ARS Grassland, Soil and Water Research Laboratory near Riesel, TX were evaluated for P inputs and P outputs to determine phosphorus budgets for 15 years of annual application of poultry litter ranging from 75 – 219 kg P ha<sup>-1</sup> yr<sup>-1</sup> on cultivated and pasture/grazed fields. The cumulative net P continued to increase regardless of the application rate and had a positive relationship with soil level P (Mehlich-3 P) and flow weighted mean concentration (FWMC) for dissolved reactive P for both cultivated and pasture managed fields. We assessed hydrological connectivity within two nested watersheds by using the before-after-control-impact (BACI) design. Results showed hydrological connectivity during high rainfall years whereas low rainfall years had minimal connectivity compared to the controls. These results suggest the P contributions from upstream fields receiving poultry litter, even at high application rates, did not exhibit a treatment effect during the low rainfall years at downslope monitoring stations. </p><p><br></p> <p>As nutrient source variability increases in nutrient management plans, improving our ability to differentiate P sources and their fate in soils is critical. We evaluated soils with unique P inputs: inorganic P, poultry litter, and cattle grazing for isotopic signatures by forming silver phosphate and determining the δ<sup>18</sup>O<sub>P</sub>. Isotopic signatures of the oxygen molecules which are strongly bound to P, provided signatures of 17.09‰, 18.00‰, and 17.20‰ for fields receiving commercial fertilizer, poultry manure, and cattle grazed, respectively. Significant effort was made to determine critical steps in the method to successfully precipitate Ag<sub>3</sub>PO<sub>4 </sub>for analysis. Results show adding a cation removal step as well as monitoring and adjusting pH throughout the method increases probability of successful Ag<sub>3</sub>PO<sub>4 </sub>precipitation. Findings from this study provide a valuable framework for future analysis to confirm unique δ<sup>18</sup>O<sub>P</sub> signatures which can be used to differentiate the fate of different phosphorus sources in agricultural systems.</p>
296

Analýza volně pohozených odpadů v chráněných územích ČR / Analysis of Littering in the protected areas of the Czech Republic

Hejdová, Jiřina January 2010 (has links)
The problems of litter are now getting to the forefront of attention in the realm of waste research. The phenomenon of littering is monitored especially in towns, but not so much outside the urbanized areas. Waste represents, for both esthetic and conservationist reasons, an undesirable phenomenon. This holds true for the protected areas in particular. This Master's Thesis is concerned with the analysis of litter, which should be the first step in the prevention and solution of the problems of littering. Three protected landscape areas and two national parks were chosen for this survey. Two tourist trails were selected in each protected area - the main and the minor one. The collection of litter was carried out in spring, summer and autumn. Collected waste was categorized at first and then a number of pieces, weight and volume were set for each category concerned. The largest amount of litter was collected in the National park Krkonoše and the smallest in the Protected landscape area Kokořínsko. The largest number of litter pieces is represented by cigarette waste, followed by plastic and hygienic waste. PET bottles were the most common type of litter pieces found in the category of beverage containers. Three quarters of all litter was found on the main trails. The most litter was collected in the...
297

Fragmentation Behaviour of Plastic Litter in the Marine Environment

Reuwer, Ann-Katrin 31 May 2022 (has links)
The marine environment is polluted by plastics of all forms and sizes. To reduce this serious pollution, it is important to identify its sources. This work focuses on the me-chanically induced breakdown of plastic into smaller fragments as a source of secondary microplastic, the time scale in which these microplastics are formed as well as the influ-ence of different environmental conditions like matrix conditions, collision potential or UV irradiation on the abrasion and fragmentation behaviour of plastic debris. Since a systematic investigation of parameter influence is not possible in the environ-ment, laboratory experiments were developed to simulate natural conditions such as drift on the beach or wave action in the (low tide) surf and swash zone. For this purpose, selected plastic objects (PET bottles, HDPE caps, PS cups and LDPE bags) were ex-posed to collision and/or friction forces under different conditions. Besides visual in-spection of the destruction procedure, a number of different methods was used to char-acterize the process, e.g., counting of visible fragments (larger than 350 μm), micro-scopic analysis of the surface structure (binocular, SEM) and highly resolved analysis of particle numbers in the size range below 350 μm. In order to extract microplastic parti-cles (<5 mm) from the matrix, extraction methods were developed that were adapted to the given sample properties (matrix volume). Furthermore, based on the particle num-bers, the power law model was applied to analyse the fragmentation process in the con-text of the observed particle size distributions. Plastic samples exhibited various signs of mechanical impairment in form of surface abrasion, cracks, tears, perforation, crumpling and finally fragmentation. The formation of fragments in different sizes (macro-, meso- and microplastics) was observed. The plastic objects were classified according to their degree of destruction to elucidate the effect of the different experimental conditions. Results show that fragmentation and abrasion depend on individual properties of the plastic objects such as thickness or shape and on the potential of weakening the plastic structure by mechanical forces (collisions) or chemical degradation (UV irradiation). Environmental conditions also influence the plastic damage; surface abrasion plays a major role on the beach; fragmentation will most likely happen in the surf- and in the swash zone. However, both processes occur simultaneously and interact with each oth-er. Formation of secondary microplastics was shown to be likely in the marine environ-ment; it must therefore be considered as an important process in the light of microplastic contamination.
298

Saprotrophic Capacity of Endophytic Fungi

Davis, Emily L. 27 July 2021 (has links)
Endophytic fungi inhabit the living tissue of a host plant for at least a portion of their life cycle. While some researchers have shown that various endophytic fungi participate in litter decomposition, we do not know whether such fungi are actually saprotrophic, meaning that they can obtain energy from litter. Therefore, I determined if endophytic fungi are saprotrophs using leaf litter as the energy source. All 49 tested isolates were found to be saprotrophic. To compare the saprotrophic capacities of fungi from different habitats, which produce different types of litter, a universal litter proxy needs to be used. I hypothesized that pure cellulose would be an adequate proxy for litter for in vitro studies because of its abundance in litter. This was tested in the first study. Saprotrophic capacity on pure cellulose was not highly correlated with that on leaf litter. I conclude, therefore, that cellulose may not be a good proxy for leaf litter. Some endophytic fungi are biotrophs, presumably acquiring energy from photosynthate produced by the host plant. This suggests that the level of exposure to sunlight by the plant should influence the competitive ability of such fungi. If saprotrophic endophytic fungi do exist, they ought to be less competitive against biotrophic endophytic fungi in leaves receiving full sunlight than in shaded leaves. I, therefore, hypothesized that the frequency of saprotrophy will be influenced by the level of sun exposure of the leaf from which the fungi were isolated. This was tested in the second study. Moreover, because closely related organisms ought to be more similar to each other than more distantly related organisms, I also hypothesized that saprotrophic capacity has a strong phylogenetic component, which was also tested in the second study. Unexpectedly, isolate identity within genus accounted for far more variability in saprotrophic capacity than genus identity, and sun exposure did not have a significant effect on saprotrophy. These results suggest that saprotrophic capacity may not be highly consequential in the ecology of these organisms.
299

Exploring differences in methods of self-reporting data for increased engagement in litter picking

Magnusson, David January 2021 (has links)
The aim of this study was to compare and present differences between two methods of self-reporting data in the use-case of litter picking, how they affect the potential of engagement in the activity of picking- and reporting litter and if they can be beneficial for behaviour change. The first being a virtual button in the user interface of a mobile phone application and the other being a physical Bluetooth button called Flic connected to the application. By recruiting ten students, the participants used the application along with both methods to report litter picks over two weeks. Using semi-structured interviews with the participants and collecting data on their picking behaviour, with the help of a thematic analysis, resulted in a few themes that were recurring experiences expressed by the users: Benefits and weaknesses, Preference, Engagement, Future usage and Social aspect. Subjective- and objective measures of engagement are also presented based on the responses from the interviews and data regarding specific picking behaviour. The results indicate a preference for Flic and it was also perceived as the method that could provide the highest engagement. The biggest reported differences between them were the aspect of tangibility and simplicity of Flic and the accessibility with using UI-reporting. Even if Flic was the preferred method, weaknesses regarding losing it or obtaining one indicates it would not work as a stand-alone solution in the case of litter picking. A combination would therefore be the optimal solution. / Målet med studien var att jämföra och presentera skillnader av självrapportering av data mellan två metoder i en skräpplocknings applikation, dess potential för att skapa engagemang och rapportera, samt om de kan vara lämpliga för beteendeförändring inom skräpplockning. Den första metoden är genom en virtuell knapp i applikationens användargränssnitt och den andra är genom en fysisk Bluetooth-knapp som heter Flic som är kopplad till applikationen. Tio studenter rekryterades för att använda applikationen och rapportera skräpplockning med hjälp av metoderna under två veckor. Användning av semistrukturerade intervjuer och insamling av deltagarnas data, med hjälp av en tematisk analys, resulterade i ett antal teman som var återkommande mellan användarna för båda metoderna: Fördelar och nackdelar, Preferens, Engagemang, Framtida användning samt Social aspekt. Subjektiva- och objektiva mått av engagemang presenteras också baserat på svaren från intervjuerna och den insamlade datan. Resultatet indikerar en preferens för rapportering med Flic och den uppfattades även som den metod som skulle kunna leda till högst engagemang till att plocka och rapportera skräpplock. Även om Flic var den föredragna metoden så antyder nackdelarna att exempelvis få tag i en samt rädsla att tappa bort den, att metoden troligtvis inte skulle fungera som en självständig lösning. En kombination skulle därav vara den bästa lösningen i fallet av självrapportering av skräpplockning.
300

Species Richness of Soil and Leaf Litter Tardigrades in the Great Smoky Mountains National Park (North Carolina/Tennessee, USA)

Nelson, Diane R., Bartels, Paul J. 02 August 2013 (has links)
A large database now exists for tardigrades in the Great Smoky Mountains National Park (GSMNP) consisting of 780 samples, 15,618 specimens, and 80 species including 14 new to science. We found 43 species of tardigrades in 150 soil/leaf litter samples. We calculated the Chao 1 species richness estimate with the species accumulation curve for the GSMNP and confirmed that our species list is virtually complete. Compared with soil data from mt. Fuji, Japan, estimated species richness in GSMNP was significantly higher. In our comparison of previous studies of soil/leaf litter tardigrades in other geographic areas, only the Kanagawa prefecture of Japan reported a higher number of species (47) than the GSMNP. Species richness estimators are valuable tools for comparing diversity in different habitats, even when sampling effort varies between studies.

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