Citrus black spot (CBS), caused by Guignardia citricarpa Kiely, occurs in various citrus producing regions of the world. Due to the potential phytosanitary risk associated with the export of fruit from CBS positive production areas to CBS-free countries, restrictive trade barriers have been introduced. This study aimed to further elucidate some epidemiological aspects of CBS that can be used to address critical questions identified in the pest risk assessment submitted by South Africa to the World Trade Organisation to address phytosanitary trade restrictions. Results indicated that Eureka lemon leaf litter exposed to viable pycnidiospores under controlled conditions or in the field in different production regions of South Africa, were not infected and colonised by G. citricarpa. Symptomatic CBS fruit or peel lying on the ground underneath citrus trees therefore can not lead to infection and colonisation of freshly detached leaves or leaf litter, or represent a source of inoculum in citrus orchards. Symptomatic fruit therefore pose no danger for the establishment of the pathogen in CBS-free orchards and are not considered to be a pathway for the pathogen. The period of leaf susceptibility to G. citricarpa was indicated to be maximum eight and ten months from development, for Valencia orange and Eureka lemon, respectively, in a greenhouse study. The susceptibility period of citrus leaves to infection by the black spot pathogen could be longer than previously perceived. Ascospores were captured, using the newly developed Kotzé Inoculum Monitor (KIM), from natural Valencia orange and Eureka lemon leaf litter during October to March with peak ascospore availability between December to February. The KIM is the first sampler designed to capture fungal spores directly from plant material in the laboratory without environmental influences and was effectively used to confirm that ascospores production is seasonal. The KIM in combination with environmental data can be used to improve control through more targeted fungicide applications. Techniques such as isolations and DNA amplification with species-specific primers to detect the pathogen directly from symptomless green leaves have a low success rate due to the restricted growth of the pathogen in latently infected tissue. Artificial leaf wilting enhanced the detection of G. citricarpa from symptomless leaves. Leaf wilting is a reliable, fast and effective method to detect the CBS pathogen and can be applied to monitor citrus nurseries and orchards throughout the year. It can also be applied to monitor pest-free orchards to maintain its CBS pest-free status. This study confirmed that sanitation practices, such as leaf litter removal and mulching of leaf litter with wheat straw can decrease the primary inoculum, ascospores, of CBS and contribute to better management of the disease in a commercial orchard. Regardless of the prevailing climatic conditions each year, control achieved through leaf litter management resulted in >95% clean fruit and are equal to the control achieved with industry standard fungicides. This approach provided improved integrated disease control and an alternative to chemical control. / Thesis (PhD)--University of Pretoria, 2010. / Microbiology and Plant Pathology / unrestricted

Peccaries are known to play a significant role in shaping the diversity of habitats and structure of plants in rain forests. However, very little is known about their roles in regulating animal populations. I review the ways peccaries increase disturbance, create habitat diversity, provide resources, act as predators, and might otherwise directly and indirectly affect other animals. To determine effects of simulated peccary extirpation on the detrital food web, I examined the hypotheses that a reduction of peccary density on fenced exclusion plots would cause changes in the amount and quality of leaf litter as habitat for leaf litter reptiles and amphibians. I found that compared to open controls, exclusions had significantly deeper litter and more rapid cellulose decomposition. Exclusions were thus expected to provide more habitat and prey for litter amphibians and reptiles than control plots, but, paradoxically, encounters of reptiles and amphibians were greater on controls.

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.

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.

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.

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第19877号 / 地環博第151号 / 新制||地環||30(附属図書館) / 32913 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)准教授 深町 加津枝, 教授 柴田 昌三, 教授 星野 敏 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM

No description available.

Streams and terrestrial ecosystems are linked through allochthonous organic matter inputs from streamside vegetation. This allochthonous material makes up the energy base for forested aquatic food webs. Therefore, removal of riparian vegetation associated with agricultural land use affects stream ecosystem structure and function. The objectives of this study were to measure and compare allochthonous input and leaf breakdown rates along a gradient of agricultural land use in southern Appalachian streams. Study streams were placed into the following land use categories: forest and light, moderate, and heavy agriculture. Several physical, chemical, and biological parameters also were measured including discharge, temperature, nutrient concentrations, macroinvertebrate abundance and density, periphyton biomass, and chlorophyll a concentration. In forested, light agricultural, and moderate agricultural streams, the quantity and quality of allochthonous input were not significantly different. However, the timing and composition of allochthonous materials were related to land use. Chlorophyll a and periphyton biomass did not vary among land use types. Leaf breakdown rates were significantly faster in light and moderate agricultural streams in comparison to forested and heavy agricultural streams. Slow breakdown rates in forested streams resulted from low nutrient concentration and cool stream temperature. The scarcity of shredding macroinvertebrates and sedimentation probably limited leaf breakdown in heavy agricultural streams. Though limited riparian vegetation along agricultural streams resulted in an energy supply equivalent to forested streams, agricultural land use may still have long term impacts on stream structure including nutrient concentrations, temperature, macroinvertebrate community, and sedimentation thus affecting stream ecosystem function. / Master of Science

In den meisten Ländern Mitteleuropas gilt weniger als ein Prozent des verbleibenden Laubwaldes als ungestört und temperierte Wälder sind Herausforderungen wie Arteninvasion, Klimawandel und steigender Stickstoff(N)-Deposition ausgesetzt. In der Vergangenheit wurde gezeigt, dass hohe N-Einträge N-Limitierungen verringern, Phosphor(P)aufnahme behindern und P-Mängel in der Buche auslösen können. Die Artendiversität von Bäumen kann die Bestandsproduktivität durch die Prozesse Komplementarität und Facilitation (Wachstumserleichterung) erhöhen, wenn diese einen wachstumslimitierenden Nährstoff betreffen. Ein Schlüsselprozess im Nährstoffkreislauf ist der Weg von Nährstoffen durch die mikrobielle Biomasse während der Dekomposition. Es wurde gezeigt, dass die mikrobielle Biomasse um N bspw. mit Buchen und um P mit tropischen Moorpflanzen konkurriert. Die Buche ist eine sehr konkurrenzfähige Baumart in temperierten Waldökosystemen aber kann von der Eiche in trockenen Bereichen übertrumpft werden, während Hainbuche und Linde eine geringere Rolle spielen. Eichen erfahren jedoch in der jüngsten Vergangenheit in europäischen Wäldern einen Rückgang, der womöglich auf hohe N-Einträge zurückzuführen ist. Für diese Arbeit untersuchten wir die Nährstoff-, Konkurrenz- und strukturelle Dynamik eines unbewirtschafteten, sehr naturnahen Laubwaldes in Mitteldeutschland, der aus Buche (Fagus sylvatica), Eiche (Quercus petraea und Quercus robur), Hainbuche (Carpinus betulus) und Linde (Tilia cordata und Tilia platyphyllus) aufgebaut ist. Unsere Ziele waren (1) zu erforschen, ob Komplementarität und/oder Facilitation die Produktivität in diesem Waldökosystem erhöht, (2) festzustellen, ob es Konkurrenz um die Nährstoffe N, P und K zwischen Bäumen und mikrobieller Biomasse gibt und, (3) die Nachbarschaftsdynamik der genannten Baumarten zu untersuchen und herauszufinden, ob der Eichenrückgang mit hoher N-Deposition einhergeht. In Beständen einer Art sowie verschiedenen Mischbeständen aus je drei Arten ermittelten wir Biomasseproduktion und Nährstoffverfügbarkeit. Nährstoffnutzungseffizienzkurven (Nährstoffnutzungseffizienz = Biomasseproduktion pro verfügbare Nährstoffe) wurden genutzt um festzustellen, ob ein bestimmter Nährstoff das Baumwachstum limitiert. Die jährliche Netto-Nährstoffveränderung wurde in einer Laubbeutel-Studie als Differenz zwischen ursprünglichem und verbleibendem Nährstoffgehalt des sich zersetzenden Laubfalls nach einem Jahr kalkuliert. Die Nährstoffresorptionseffizienz berechneten wir über die Ermittlung der N-, P- und Kalium(K)-Konzentrationen in sonnenexponierten Blättern und im gefallenen Laub. Die Nachbarschaftsdynamik von Bäumen wurde über die Durchmesserverteilung, überirdische Holzbiomasse für jede Artenkombination sowie eine Polygon-Abschätzung von Wachstumsräumen erforscht. Zusätzlich wurde eine durchmesserbasierte nearest neighbor(nächster-Nachbar)-Analyse für Baumpaare durchgeführt. Ein Geographisches Informationssystem (GIS) wurde genutzt um Wachstumsraum-Polygone zu erstellen und nächste Nachbarn zu bestimmen. Auf Einzelbaum-Level, ermittelt durch einen Nachbarschaftsansatz, waren relative Wachstumsraten von Buchen im Einzelbestand geringer als in der Mischung mit Linde und Hainbuche während das Wachstum von Linde im Einzelbestand größer war als in Mischung mit Buche und Eiche. Die Nährstoffnutzungseffizienzkurve für Buche zeigte optimale P- und K-Nutzungseffizienz für die Art in Mischbeständen, während sie in Einzelbeständen  P- und K-limitiert war. Während die jährliche Netto-Nährstoffveränderung in sich zersetzendem Blattlaub die Verfügbarkeit von P und K im Boden beeinflusste, war dies für N nicht der Fall. Resorptionseffizienzen von N, P und K hingen negativ mit der jährlichen Netto-Nährstoffveränderung zusammen. In unserer Studie zur Nachbarschaftsdynamik von Bäumen fanden wir heraus, dass intraspezifische nearest neighbors gleiche Durchmesser aufwiesen und ihren Durchmesser gleichzeitig mit dem des Nachbarn vergrößerten. Im Gegensatz dazu waren die Durchmesser von interspezifischen nearest neighbors im Allgemeinen unterschiedlich und der Durchmesser des Nachbarn verringerte sich mit zunehmendem Durchmesser des Zielbaums. Eichen konnten ihren Wachstumsraum mit zunehmendem Durchmesser nicht vergrößern, aber dominierten ihre nearest neighbor über die Größe. Unsere Ergebnisse zeigten, dass im untersuchten Waldökosystem Nährstofflimitierungen artabhängig waren und dass die Nutzung von Nährstoffnutzungseffizienz und Nachbarschaftsansatz geeignete Mittel sind, den Einfluss einzelner Baumarten auf die Produktivität einer Art im Rein- und Mischbestand zu ermitteln – so wie die beobachtete Facilitation der Buche im Mischbestand. Diese Werkzeuge stellen eine wichtige Basis zur verbesserten Bewirtschaftung typischer temperierter Mischwälder dar. Wir schlussfolgerten weiterhin, dass Konkurrenz zwischen mikrobieller Biomasse und Bäumen für P und K hoch, aber für N weniger bedeutend war, was wahrscheinlich in hoher N-Deposition in diesem Waldökosystem begründet liegt, welche den internen N-Kreislauf entkoppelte. Die hohe N-Deposition trug wahrscheinlich auch zu geringer Verjüngung der Eiche bei, während ältere Eichen in unserem Untersuchungsgebiet im Wettbewerb um Licht erfolgreich waren. Die Bestandsstruktur war charakterisiert durch stärkere interspezifische verglichen mit intraspezifischer Konkurrenz. Daraus resultierend bildeten Reinbestände aus Buche, Eiche und Linde Klimaxbestände hoher Biomasse innerhalb eines sich verändernden, kleinskaligen Mosaiks verschiedener Artenzusammensetzungen. In Reaktion auf neue Bewirtschaftungsanforderungen des Globalen Wandels sind weiterführende Forschungen zu Nutzungseffizienz unterschiedlicher Ressourcen für Baumarten in verschiedenen Zusammensetzungen empfehlenswert.

A diversidade da Mata Atlântica está constantemente ameaçada devido à perda de habitats provocada pela destruição e alteração dos ambientes naturais. Este fato é muito preocupante, pois os remanescentes florestais da Mata Atlântica encontram-se, em sua maior parte, em pequenos fragmentos altamente perturbados, acarretando em perda de biodiversidade da fauna existente. Muitos estudos demonstraram que mamíferos e aves especialistas (e. g. insetívoros) são muito sensíveis à fragmentação ambiental, tendendo a desaparecer em áreas abertas. A perda destes animais pode alterar a densidade de artrópodes e as taxas de herbivoria, ocasionando um efeito cascata (top- down), que causará influência até na decomposição e ciclagem de nutrientes. Entretanto o estudo de como esse efeito top-down ocorre em diferentes coberturas de solo ainda não foi testado, desta forma, objetivou-se investigar como as taxas de decomposição são modificadas pela exclusão experimental de vertebrados em áreas com diferentes coberturas vegetais na mata Atlântica. Parcelas de exclusão de vertebrados e parcelas controle foram alocadas em áreas com coberturas vegetais de pastagem e floresta, para verificar como ocorre o efeito top-down na decomposição. Utilizaram-se três tipos de serapilheira diferentes, uma gramínea (Brachiaria decumbens), uma espécie pioneira (Tibouchina sellowiana) e uma mistura de folhas de diferentes espécies da floresta primária adjacente. A técnica dos litter bags foi utilizada para avaliar as diferentes taxas de decomposição e foram coletados em intervalos de 16, 36, 71, 181 e 247 dias. O resíduo vegetal foi limpo, seco e pesado para obtenção das massas remanescentes (%) e taxa de decomposição, após isso o material foi triturado e pesado em subamostras para analises de nutrientes e compostos orgânicos (nitrogênio, carbono, fósforo, lignina, celulose e polifenóis). A taxa de decomposição não diferiu entre os tratamentos controle e exclusão de vertebrados, desta forma, não foi possível observar o efeito top-down da exclusão de vertebrados neste estudo, provavelmente devido à elevada biodiversidade da fauna do solo na área onde o experimento foi realizado e sugere-se repeti-lo em uma área menor e mais desconectada, com a finalidade de simular como o efeito cascata ocorre em pequenos fragmentos da mata Atlântica. Além disso, a decomposição foi mais rápida nos litter bags localizados na floresta do que na pastagem e as folhas de gramínea tiveram maior perda de massa do que as folhas de floresta primária e T. sellowiana, possivelmente devido às interações entre nitrogênio, lignina e a relação C:N dos resíduos vegetais. / The diversity of Atlantic forest is constantly threatened due to habitat loss caused by the destruction and alteration of natural environments, and most of the biome is now in small and fragmented areas. This fact is of a great concern, because the remaining areas in Atlantic forest are in small highly disturbed fragments, resulting in loss of biodiversity of the existing fauna, like mammals and birds. Many studies have shown that specialist mammals and birds (e.g. insectivores) are very sensitive to environment fragmentation and tend to disappear in open areas. The loss of these animals is likely to cause an increase in the density of arthropods and rates of herbivory, causing a top-down effect that may even influence the cycling of nutrients. We aimed to investigate how decomposition rates are modified by the experimental exclusion of vertebrates in an area with different land coverage in the Atlantic forest. Vertebrate exclusion plots and control plots were allocated in areas with different land coverage (pasture and forest) to evaluate the top-down effects in decomposition. We used three different kinds of leaves, being one grass (Brachiaria decumbens), one very common primary specie of the area (Tibouchina sellowiana) and a mix of primary forest leaves. Litterbags were used to evaluate the decomposition rate and it was collected during intervals of 16, 36, 71, 181 and 247 days. The vegetal residue was cleaned, dried and weighted to obtain the remaining mass (%) and decomposition rate, after that, the material was milled and weighted in subsamples for analyses of nutritional quality (N, C, P, lignin, cellulose and polyphenols). The decomposition rate was not different for the control and vertebrate exclusion plots, as a result, it was not possible to show the top-down effect in decomposition, possibly because of the high soil biodiversity in the area where the experiment was done. It would be very important to remake this experiment in a smaller and more disconnected area, in order to show how this cascade effect occur in Atlantic forest´s smaller fragments. Furthermore, the decomposition was faster at the forest plots than at the pastureland plots and the grass leaf litter presented the higher decomposition rate than the primary forest leaves and T. sellowiana and it was possibly caused by the interaction between nitrogen, lignin and C:N ratio.