Várias podem ser as causas da variação local no sucesso reprodutivo de espécies vegetais, sendo a disponibilidade de recursos abióticos, herbivoria, polinização e dispersão de sementes comumente consideradas. Em espécies distílicas, a variação na disponibilidade de recursos abióticos pode determinar diferenças na quantidade e no período de produção das estruturas reprodutivas, e estas por sua vez podem influenciar a interação planta polinizador, modulando o comportamento de forrageio de visitantes florais. Este trabalho teve como objetivos verificar como alguns fatores poderiam determinar variação na fenologia e no sucesso reprodutivo de Psychotria suterella, uma espécie arbórea distílica comum em florestas no sudeste do Brasil. Os fatores experimentalmente investigados foram água, luz, nutrientes inorgânicos e superfície foliar. Além disto, investigamos a resposta de abelhas Bombus, B. brasiliensis e B. morio, à disponibilidade de recursos florais em quatro escalas espaciais. A variação na oferta de recursos não afetou o padrão temporal sincrônico de emissão de botões e desenvolvimento de flores dos tipos florais de P. suterella, mas condicionou alterações na quantidade das estruturas reprodutivas produzidas de forma distinta em cada tipo floral. Plantas com morfologia floral longistila parecem estar se reproduzindo sob condições ambientais limitantes, em função de responderem positivamente ao aumento na disponibilidade de recursos, enquanto plantas com morfologia floral brevistila parecem estar melhor adaptadas às condições ambientais, uma vez que responderam negativamente a todos os tratamentos. Respostas fisiológicas singulares parecem ser as responsáveis por essas diferenças. Não houve variação no número de flores, energia produzida no néctar das flores e freqüência de visitas a flores e plantas para os tipos florais de P. suterella. A oferta de energia por flor e a freqüência de visitas por flor variaram entre plantas. Bombus morio e Bombus brasiliensis responderam à variação na disponibilidade de recursos florais de P. suterella em escala espacias menores que 5m, visitando com mais freqüência plantas com maior oferta de energia, independente da disponibilidade energética na vizinhança. Porém, a freqüência de visitas média por flor não apresentou relação com a quantidade de recursos florais nas plantas, e não foi influenciada pela densidade de energia nas demais escalas, fato que deve estar relacionado à grande variação na produção de néctar entre as flores dentro de uma mesma planta. / Several factors might cause intrapopulational variation in plant reproductive success, being often mentioned abiotic resource availability, herbivory, pollination and frugivory as possible factors. In distylous species, the variation on abiotic resources availability can determine differences in quantity as well as in the moment of emisssion of reproductive structures. Those structures might influence the plant-pollinator interaction, modeling foraging behaviour of floral visitors. The aims of this study were to identify how variation in some abiotic resources change the phenology and reproductive success of Psychotria suterella, a common distylous species from Brazilian southeastern forests. We experimentally changed the amounts of light, water, inorganic nutrients and foliar surface. In addition, we measured the frequency of Bombus, B. brasiliensis and B. morio, in relation to floral density at four spatial scales. The variation in abiotic resources availability did not change the temporal pattern of flowering in both, pin and thrum morphs, although bud and flower number was different. Pin plants seemed to be under restrict environmental conditions because the addition of resources increased the number of reproductive structures. On the other hand, any alteration in environmental resources affected negativelly thrum plants. We did not register variation in flower number, energy production in nectar, plant and flower visitation rates for both P. suterella floral morphs. Energy supply per flower and flower visitation rates varied among plants. Bombus morio and Bombus brasiliensis responded to availabitity of floral resources in spatial scales smaller than five meters, visiting more frequently plants with more energy reward regardless of neighbourhood energetic availability. The flower visitation rate was not related to flower resource availability in P. suterella plants. This result might be determined by the high variation in flower energy production within plant.

Submitted by (lucia.rodrigues@ufrpe.br) on 2017-03-23T15:49:15Z No. of bitstreams: 1 Wagner Rogerio Leocadio Soares Pessoa.pdf: 1202325 bytes, checksum: 24359deb95d67f77dc4011b48213d142 (MD5) / Made available in DSpace on 2017-03-23T15:49:15Z (GMT). No. of bitstreams: 1 Wagner Rogerio Leocadio Soares Pessoa.pdf: 1202325 bytes, checksum: 24359deb95d67f77dc4011b48213d142 (MD5) Previous issue date: 2005-02-28 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The banana is the second largest fruit more consumed in the world, being the fresh fruit that detain the largest market. Brazil blunts as second largest producer of the fruit. In Brazil the varieties Silver and Pacovan approximately 60 % of the cultivate area. However, several phytopathological factors such as fungi and bacteria can cause the banana crop losses that could reach up to 40 %. Among these factors, anthracnose caused by Colletotrichum musae, deserve special attention in harming the commercialization and the consumption in natura. Because of the importance of this disease in banana and the lack of information on the subject, this work had two objectives: 1) study the influence of inoculation methods, different temperatures associates to different wetness period on the development of the disease; 2) verify alterations physicalchemistry happened in the banana fruits. The fruits were inoculated with 17 isolated of C. musae in two ways using PDA disk containing structures of the pathogen and suspension of conidia 4x 106 conidia / mL. The banana fruits were inoculated with the pathogen in the presence or not of artificial wounds. All C. musae isolates were pathogenic independently of the inoculation method used. Lesions could be observed in artificially wounded fruits independently of the inoculation method used (disk and suspension). In order to access the influence of temperature and wetness period, the isolates MAG2, SFV1 and FSA of C. musae were used isolated. These isolates were chosen because they show a wide rage of aggressiveness in the pathogenicity test. The bananas fruits were inoculated and incubated in the temperatures of 10, 15, 20, 25 and 30 oC with periods of wetness of 0, 12, 24 and 36 h, during five days. Temperatures of 20, 25 and 30 oC and with increasing wetness periods favored the development of lesions. Largest lesions wereobserved in the temperatures around 25 to 30 oC and 36 h of wetness period. Several physicalchemical alterations could be observed in the fruits during thexperiment: 1) there was an increase in the banana fruit humidity as the temperature and the wetness period increased, 2) They reach its highest pH value at 30 oC independently of the wetness period, 3) The largest ATT for the isolates SFV and MAG occurred at the same temperature of 25 oC, with wetness period of 12 and 24 h, respectively. The largest ATT value for the isolate FSA occurred at the temperature of 15 oC associated to the wetness period of 36 h, 4) Maximum SST occurred at temperature around 20 oC independent of the wetness period, 5) The largest potassium levels was reach at the temperature of 10 oC with wetness period of 24 h for SVF and MAG and without wetness period in FSA, 6) The total sugars content increased with the elevation of the temperature, decrease as the temperature approached of 30 oC, independent of the wetness period and the isolated of C. musae used. / A banana é a segunda fruta mais consumida no mundo, sendo (a fruta fresca neste contexto detentora de maior mercado no mundo) o Brasil segundo maior produtor, utilizando as variedades Prata e Pacovan em aproximadamente 60% de sua área cultivada. Entretanto, diversos fatores podem ocasionar perdas na produção, podendo chegar à ordem de 30 a 40%. Entre estes fatores encontram-se fungos e bactérias, merecendo destaque especial na pós-colheita a antracnose, causada por Colletotrichum musae, prejudicando a comercialização e o consumo in natura. Diante da importância desta doença na banana e a carência de informações sobre o assunto, este trabalho teve por objetivos, estudar a influência de métodos de inoculação, diferentes temperaturas associadas a distintos períodos de molhamento sobre o desenvolvimento da doença, e sua influência nas características físicoquímica. Avaliaram-se 17 isolados de C. musae, utilizando-se dois tipos de inóculo: disco de meio BDA contendo estruturas do patógeno e suspensão de conídios 4x106 conídios/mL, em duas formas de inoculação: com e sem ferimentos. Todos os isolados de C. musae mostraram-se patogênicos independente do tipo de inóculo utilizado. As lesões ocorreram nas frutas com ferimento, independente do tipo de inóculo (disco e suspensão). Para o estudo da influência da temperatura e período de molhamento, utilizaram-se três isolados do patógeno MAG2, SFV1 e FSA, por mostraram-se mais agressivo, intermediário e menos agressivo, respectivamente, no teste de patogenicidade. Asfrutas foram inoculadas e incubadas nas temperaturas de 10, 15, 20, 25 e 30oC e períodos de molhamento de 0, 12, 24 e 36 h, por cinco dias. As temperaturas em torno de 20, 25 e 30oC independente do período de molhamento favoreceram um maior desenvolvimento de lesões. As alterações físico-química mostraram que houve um aumento de umidade da fruta à medida que a temperatura e o período de molhamento aumentavam. Valores mais elevados de pH ocorreram em torno da temperatura de 30oC, independente do período de molhamento. Em relação a Acidez Titulável Total (ATT) para o isolado SFV1 e MAG2 ocorreu na temperatura ao redor de 25oC, com período de molhamento de 12 e 24 h, respectivamente, e para o isolado FSA ocorreu ao redor da temperatura de 15oC associado ao período de molhamento de 36 h. O teor de Sólidos Solúveis Totais (SST) ficou em volta de 20oC independente do período de molhamento. A temperatura ao redor de 10oC favoreceu a elevação no nível de potássio das frutas, associado ao período de molhamento de 24 h, em frutas inoculadas com os isolados SVF1 e MAG2, e 0 hora quando utilizou-se o isolado FSA. Os teores de açúcares totais aumentaram com a elevação da temperatura, declinando à medida que esta se aproximava de 30oC, independente do período de molhamento e isolados de C. musae.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-12-10T09:16:06Z No. of bitstreams: 2 Dissertação - Marília Gomes Ismar - 2015.pdf: 4948439 bytes, checksum: bd3576f60e294eec74befd6da3509e2b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-12-10T09:17:53Z (GMT) No. of bitstreams: 2 Dissertação - Marília Gomes Ismar - 2015.pdf: 4948439 bytes, checksum: bd3576f60e294eec74befd6da3509e2b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2015-12-10T09:17:53Z (GMT). No. of bitstreams: 2 Dissertação - Marília Gomes Ismar - 2015.pdf: 4948439 bytes, checksum: bd3576f60e294eec74befd6da3509e2b (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-09-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Among the Brazilian agribusiness activities, livestock stands out as an important production sector, with major contribution to the economy. In this activity, the pastures are the cheapest method for livestock, but it is still an uncommon method to some producers as they consider highly costly the refurbishment or renovation of pastures. It is estimated that 80% of these areas are in poor condition throughout the Brazilian territory, and at “Goiás”, where 67% of its native vegetation has been replaced by some agricultural activity, the situation is quite worrying, with seven micro-regions with more than 30% of pasture areas at some stage of degradation, however, the causes haven’t yet been scientifically demonstrated. At this context, this study has aimed to list and analyze which are the pasture degradation factors that contribute to the high level of these processes at those micro-regions. Two counties at the Northwest mesoregion and three at the Middle mesoregion were studied, randomically chosen, and evaluated 5% of each one of those proprieties. Producers from different social classes and educational level were studied, as well as small, medium and large farms, defined by the Brazilian Law n° 8.629/93. Analyzing the bibliographic review, becomes evident that at least 16 pasture degradation factors are quite substantial, according to the “Anuário Estatístico da Pecuária de Corte (2000)” and the “Macedo et al (2012)”. However, at “Goiás” region, based on this study, added to the factors discussed in the bibliographic review, it can be noticed that the most outstanding factor is the producers illiteracy. From the results obtained, the conclusion reached is that direct contact with the producer allows the technician to work on raising the awareness on the need to recovery and renewal the degraded pastures, trying to obtain the activity sustainability, aiming to increase productivity and better results in their herds. / Dentre as atividades do agronegócio brasileiro, a pecuária se destaca como importante setor de produção, com grande contribuição ao produto interno bruto. Nesta atividade as pastagens são o alimento de menor custo para a produção animal, porém, ainda é uma percepção ausente a alguns produtores, que consideram altamente dispendiosa a recuperação ou renovação das mesmas. Estima-se que 80% dessas áreas estão em condições precárias em todo o território brasileiro e, em Goiás, onde 67% de sua vegetação nativa já foi substituída por alguma atividade agropecuária, a situação é bastante preocupante, com sete microrregiões com mais de 30% de áreas de pastagens em algum estágio de degradação, porém, as causas ainda não foram demonstradas cientificamente. Considerando esse contexto, objetivou-se com este estudo elencar e analisar quais são os fatores de degradação de pastagem que mais contribuem para o alto nível desses processos nessas microrregiões. Foram estudados dois municípios da mesorregião Noroeste e três da mesorregião Centro, escolhidos por sorteio. Tendo sido avaliadas 5% das propriedades de cada um deles. Foram considerados produtores de diferentes classes sociais e nível de instrução, bem como propriedades pequenas, médias e grandes, definidas a partir da Lei n° 8.629/93. Na revisão bibliográfica fica claro que ao menos 16 fatores de degradação das pastagens são bastante consideráveis, segundo o Anuário Estatístico da Pecuária de Corte (2000) e Macedo et al (2012). Entretanto, para a região de Goiás, considerando esse estudo, somado aos fatores apresentados na revisão, pode-se notar que o fator mais impactante é o baixo nível de instrução dos produtores. A partir dos resultados alcançados, pode-se concluir que o contato direto com o produtor permite ao técnico trabalhar, sensibilizando-os da necessidade de recuperação e renovação das áreas de pastagens degradadas com o propósito de garantir a sustentabilidade da atividade,

O movimento dos animais desempenha papel importante na aptidão dos indivíduos, no fluxo gênico, na dinâmica de metapopulações e na persistência, a longo prazo, de espécies em um ambiente. Dessa forma, o objetivo deste estudo foi compreender aspectos relacionados à ecologia do movimento da rã-manteiga (Leptodactylus latrans) e da rã-touro (Lithobates catesbeianus). Para isso, indivíduos de ambas as espécies foram marcados com radiotransmissores e rastreados com o objetivo de coletar informações sobre seus movimentos. Ressaltamos os seguintes resultados deste trabalho: (1) a área de vida média de L. latrans é de 2034,2 m2; (2) com o aumento do tamanho corpóreo de anuros há o aumento do tamanho da área de vida; (3) indivíduos de L. latrans se locomovem mais em noites escuras, chuvosas e quentes; e (4) o aumento da pressão de propágulos não reflete uma maior probabilidade no aumento da distribuição geográfica de uma dada população de L. catesbeianus. Entender os padrões de locomoção dos anfíbios e como utilizam o espaço na natureza é fundamental para o entendimento de processos ecológicos e evolutivos relacionados às histórias de vida das espécies desse grupo. Além disso, esse conhecimento serve como uma ferramenta importante no estabelecimento de limites de áreas de conservação com significado biológico para espécies ameaçadas. Ainda, saber como espécies invasoras se locomovem é um dos primeiros passos para que se tomem medidas de controle populacional e para o bloqueio do avanço da distribuição de espécies exóticas / The ability of animals to move plays an important role in individual fitness, gene flow, population regulation, metapopulation dynamics and long-term persistence of species. The aim of this study was to understand aspects related to the movement ecology of the Butter Frog (Leptadactylus latrans) and the Bullfrog (Lithobates catesbeianus). We collected movement data by radio tracking individuals of both species. Some of the most important results obtained were: (1) the mean home range of L. latrans is 2034.2 m2; (2) increasing body size increases home range size in anurans; (3) individuals of L. latrans are more likely to move larger distances in dark, rainy and warm nights; (4) the increase in propagule pressure does not reflect an increase in the probability of geographical spread of a given population of L. catesbeianus. Understanding how amphibians move and use the space in nature is fundamental for the understanding of basic ecological and evolutionary processes related to life history of the species. Moreover, this knowledge is a useful tool to establish biologically meaningful conservation boundary areas to threatened species. Yet, understanding how invasive species move in nature is one of the first steps to population control and to block the spread of geographical distribution of exotic species

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As florestas tropicais amazônicas são um importante reservatório de carbono acima e abaixo do solo. Elas desempenham uma importante função tanto no sequestro do carbono atmosférico quanto no armazenamento desse carbono em forma de biomassa. O objetivo desse trabalho foi quantificar a variação espacial da biomassa arbórea viva e avaliar o efeito de variáveis climáticas e ambientais ao longo de cerca de 400 km de florestas alagadas no médio e baixo rio Branco. Especificamente, foi avaliado o efeito (i) da duração da inundação, (ii) do comprimento da estação seca e (iii) da textura e fertilidade do solo no estoque de biomassa acima do solo. Foram amostrados 2.432 indivíduos com Diâmetro à altura do Peito (DAP) ≥ 10 cm, distribuídos em 54 parcelas compridas (250 metros) e estreitas (4 metros) de 0,1 ha. Para cada indivíduo amostrado, além do DAP, foram determinadas a altura total e a densidade da madeira. A biomassa viva acima do solo das árvores foi estimada através da média de três modelos alométricos que consideram DAP, densidade da madeira e altura das árvores. A biomassa de palmeiras foi estimada com base em um único modelo que considera apenas a altura dos indivíduos. A biomassa variou de 21,5 a 245,15 Mg/ha. Não foi observada relação entre a biomassa e as variáveis climáticas (precipitação média anual e comprimento da estação seca). As variáveis ambientais: solo (% de argila) e a duração da inundação também não explicaram a variação da biomassa arbórea viva acima do solo nas florestas alagadas do rio Branco. Estes resultados representam as primeiras estimativas de biomassa arbórea para as florestas alagadas do rio Branco. A grande variação observada entre as parcelas sugere que eventos estocásticos locais, a estrutura da floresta e a composição florística podem ser mais importantes para explicar a variação da biomassa do que fatores climáticos e características do solo. / Amazonian forests are an important above and belowground carbon reservoir. They play an important role in both the sequestration of atmospheric carbon and storage of carbon as biomass. The aim of this study was to quantify the spatial variation of above ground tree live biomass and evaluate the effects of climatic and environmental predictors along ~400km of flooded forests in the middle and lower rio Branco (Roraima). Specifically, I related plot-based biomass estimates with (i) duration of flooding, (ii) length of the dry season, and (iii) texture and fertility of the soil. A total of 2.432 individuals with diameter at breast height (DBH) ≥ 10 cm where sampled in 54 long (250 meters) and narrow (4 meters) plots of 0.1 hectare. For each individual sampled, were also determined: total tree height and wood density. The above ground live biomass of trees was estimated by the average of three allometric models that consider DBH, wood density, and tree height. Palm biomass was estimated based on a single model that considers only the height of individuals. Biomass estimates presented a 10-fold variation, ranging from 21.5 to 245.15 Mg/ha. No relationship between biomass and climatic variables (mean annual rainfall and length of dry season) were observed. Environmental variables: soil (% clay) and the duration of the flood also did not explain the variation in tree biomass in the flooded forests of the rio Branco. These represent the first tree biomass estimates for the flooded forests of the rio Branco, and the large biomass variation observed in the plots suggest that local stochastic events, forest structure and floristic composition may be more important in explaining biomass variation than climatic and soil factors.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-04-17T18:05:35Z No. of bitstreams: 1 mateusfajardodefreitassalviatodetoni.pdf: 1310680 bytes, checksum: 07d34f3c206819ff6b208c6ab33be11a (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-04-18T13:50:54Z (GMT) No. of bitstreams: 1 mateusfajardodefreitassalviatodetoni.pdf: 1310680 bytes, checksum: 07d34f3c206819ff6b208c6ab33be11a (MD5) / Made available in DSpace on 2017-04-18T13:50:54Z (GMT). No. of bitstreams: 1 mateusfajardodefreitassalviatodetoni.pdf: 1310680 bytes, checksum: 07d34f3c206819ff6b208c6ab33be11a (MD5) Previous issue date: 2017 / Os ninhos de insetos sociais funcionam como a interface entre as colônias e o ambiente, e estudar como os fatores ambientais se relacionam com o comportamento de nidificação é essencial para compreender o sucesso desses animais em colonizar e sobreviver na área urbana. Dessa forma, este trabalho teve como objetivo estudar a relação entre a orientação dos ninhos da vespa social Polybia platycephala em áreas urbanas e a incidência de luz ambiental sobre os mesmos, além de descrever sua dinâmica de temperatura em relação ao microambiente em que estão localizados. Para a orientação e a incidência de luz, 11 ninhos foram selecionados em 2016 na cidade de Juiz de Fora, MG, sendo 11 na estação chuvosa e 11 na seca (n= 22). A orientação dos ninhos foi constatada e a incidência de luz de cada ninho foi verificada ao longo do dia (06:00h – 18:00h). Adicionalmente, seis ninhos tiveram sua orientação experimentalmente invertida e a luminosidade foi acompanhada antes e depois da inversão de forma a verificar o efeito da orientação natural sobre a exposição dos ninhos à luz. Para a dinâmica de temperatura utilizaram-se os mesmos 22 ninhos, e a temperatura dos ninhos e do ambiente foram medidas paralelamente à luminosidade. Para verificar o efeito da atividade das vespas sobre a temperatura da colônia, um ninho abandonado e uma colônia ativa foram acompanhados por 24 horas. Os resultados permitiram-nos concluir que P. platycephala apresenta uma orientação de ninhos fortemente enviesada para leste, aumentando a exposição à luz ambiental no período da manhã; são, no entanto, capazes de modificar esse comportamento para adaptar-se ao seu microambiente para otimizar essa exposição. A temperatura dos ninhos é muito relacionada à ambiente, flutuando paralelamente a esta, o que indica uma grande dependência das colônias do mesmo para sua sobrevivência. De forma geral, constatou-se que P. platycephala possui uma íntima relação com o seu microambiente, o que pode ajudar a explicar seu sucesso em colonizar áreas urbanas, mas também a torna sensível a alterações ambientais e climáticas nas mesmas. / Nests of social insects function as the interface between colonies and the environment, and studying how environmental factors relate to the nesting behavior is essential in order to understand these organisms’ success in settling and surviving in the urban area. On this sense, our work aimed to study the relation between the social wasp Polybia platycephala nest orientation and the incidence of environmental light, aside from describing its temperature dynamics regarding the microenvironment where it is set. In order to study nest orientation and light incidence, 22 nests were chosen in 2016 in the city of Juiz de Fora, MG, being 11 in the rainy season and 11 in the dry (n= 22). Nest orientation was verified and light incidence on each nest was assessed through the day (06:00h - 18:00h). Additionally, six nests had their orientation experimentally inverted and luminosity was assessed before and after the inversion in order to verify the effect of nest orientation on exposure to light. In order to study temperature dynamics, the same 22 nests were used, and the nest and ambient temperatures were assessed in parallel with the luminosity. In order to verify the effect of the wasp activity on colony temperatures, an abandoned nest and an active colony were observed for 24 hours. The results allowed us to conclude that P. platycephala shows nest orientation strongly biased towards east, increasing exposure to light during the morning; colonies are, however, able to perform modifications on this behavior in order to adapt themselves to their microenvironment and optimize this exposure. Nest temperatures are intensely related to the ambient, fluctuating in parallel with it, which indicates a great dependence of the colonies on the environment to assure their survival. Overall, we found that P. platycephala has an intimate relation with its microenvironment, which may help explain its success in settling urban areas, but also makes it sensible to environmental and climatic changes in them.

Abstract During the past half century several large lakes in Finland have experienced notable changes in their ecological condition, induced mainly by water level regulation, eutrophication and land use transformation. The objective of this thesis was the quantification of the spatiotemporal changes of aquatic macrophytes in Finland during the second half of the 1900s. Mapped aquatic macrophyte cover from historic (1947–1963) and present day (1996–2000) aerial photographs, additional macrophyte data and several environmental variables were used to identify the main determinants of aquatic macrophyte distribution, abundance and change. Furthermore, factors influencing the littoral paludification process were identified. The study was conducted in 24 boreal lakes (41–1116 km2) with multisource vegetation data. Selected environmental variables of water level regulation, eutrophication and geomorphology were collected and analyzed. More than 402 km of littoral shoreline in historic and present day aerial photographs was analyzed with stereoscopic visual interpretation. A total of 474 habitat level study sites were used to examine the determining environmental factors of occurrence, abundance and change of emergent vegetation. Finally, 289 vegetation transects were performed in order to study the occurrence, types and main determinants of littoral paludification. Water level regulation was found to be the primary factor behind aquatic macrophyte vegetation development at the whole lake level. The major vegetation changes were determined by the mean water level rise or reduction, decreased fluctuation range and reduced spring flood. The vegetation response was less pronounced in a lake with water level regulation similar to natural fluctuation. Eutrophication influenced aquatic macrophytes at the site level. Land use variables of tributary and agriculture, indicating nutrient increment, corresponded positively with vegetation occurrence and abundance. Geomorphology explained vegetation development at the habitat level. Clay and related deposits and the shore slope specified the vegetation occurrence and affected the abundance of vegetation. Water level regulation, eutrophication, clay and shallowness were found to influence paludification. Helophyte species, common reed (Phragmites australis) and water horsetail (Equisetum fluviatile), dominated the emergent vegetation in the studied lakes. / Tiivistelmä Viimeisen puolen vuosisadan aikana suomalaisiin suurjärviin on kohdistunut lukuisia muutoksia, jotka ovat vaikuttaneet järvien ekologiseen tilaan. Muutoksia ovat aiheuttaneet pääasiallisesti vesistöjen säännöstely, rehevöityminen sekä maankäytön muuttuminen. Tämän väitöskirjan tarkoituksena on analysoida noin viimeisten 50 vuoden aikana suomalaisissa suurjärvissä tapahtunutta ranta- ja vesikasvillisuuden pitkäaikaismuutosta. Historiallisilla (1947–1963) ja nykyisillä (1996–2000) ilmakuvilla, muilla kasvillisuusaineistoilla sekä useilla ympäristömuuttujilla tunnistettiin keskeisiä tekijöitä, jotka vaikuttivat kasvillisuuden esiintymiseen, runsauteen ja muutokseen. Tämän lisäksi tutkittiin rantojen pysyvän umpeenkasvun kehitysprosessia. Tutkimusta varten kasvillisuudesta kerättiin monilähdeaineistoa kaikilta Suomen päävaluma-alueilta yhteensä 24 eri järveltä, joiden koko vaihteli 41–1116 km2:n välillä. Tämän lisäksi useita vesistöjen säännöstelyn, rehevöitymisen ja geomorfologian ympäristömuuttujia kerättiin ja analysoitiin. Stereoskooppisella visuaalisella ilmakuvatulkinnalla tutkittiin yli 402 kilometriä rantaviivaa historiallisista ja nykyisistä ilmakuvista. Ilmaversoisen ranta- ja vesikasvillisuuden esiintymistä, runsautta ja historiallista muutosta analysoitiin 474 habitaattitason tutkimuspisteellä. Rantojen pysyvän umpeenkasvun esiintymistä, umpeenkasvun eri tyyppejä ja sitä määrittäviä tekijöitä tutkittiin 289 kasvilinjalla. Tutkimuksen tuloksena havaittiin, että järvitasolla vesistöjen säännöstely oli tärkein kasvillisuuden historialliseen kehitykseen vaikuttava tekijä. Huomattavimmat kasvillisuusmuutokset määräytyivät keskiveden noston, pienentyneen säännöstelyvälin, vähentyneen kevättulvan ja lasketun keskiveden tason seurauksena. Kasvillisuusmuutokset eivät olleet niin selviä, jos säännöstely muistutti luonnontilaista säännöstelyä. Rehevöityminen vaikutti ranta- ja vesikasvillisuuteen paikallisesti. Ravinteisuutta ilmentävät maankäytön muuttujat, ojat sekä maanviljelys, lisäsivät kasvillisuuden esiintymistä ja runsautta. Geomorfologiset tekijät selittivät kasvillisuuden kehitystä habitaattitasolla. Savinen maaperä sekä rannan mataluus lisäsivät vesi- ja rantakasvillisuuden esiintymistä sekä kasvillisuuden runsautta. Vesistöjen säännöstely, rehevöityminen, savinen maaperä sekä rannan mataluus lisäsivät rantojen pysyvää umpeenkasvua. Ilmaversoiset kasvilajit, järviruoko (Phragmites australis) ja järvikorte (Equisetum fluviatile), hallitsivat kasvillisuutta tutkituissa järvissä.

No description available.

This research develops and tests a model of the service unit ownership and control patterns used by international service companies. The main purpose of this study is to investigate trivariate causal relationships among environmental factors, organizational structure, and perceived performance in the internationalization process of service firms. A service firm operating in foreign soil has a choice of three general entry mode strategies offering different degrees of ownership and control of its remote operating units located in foreign countries -- full ownership arrangement, joint venture arrangement, and franchising arrangement. The entry mode strategies chosen depend on the factors relating to internal environment of a specific firm, industry related factors in which the firm operates, and external environment of the operating units at national context. This study identifies these factors, investigates how they affect the firm's choice of entry modes, and finally examines the impact of entry mode on firm's performance. The overall model has been explained by contingency theory that conceptualizes optimal level of ownership and control mode as a response by the firm to the interplay of environmental factors and as a determinant of firm's performance. To this core can be added complementary theories which are borrowed from agency theory, transaction cost theory, and resource dependence theory. These theories explain the linkages between market entry mode and each type of environmental factors. In order to empirically test the hypotheses, data were collected from hospitality firms regarding the ownership structure of subsidiaries located in foreign countries. As a whole, the conceptual model developed in the study received strong support from the empirical study. This study found a positive impact of contingency fit on performance and so support contingency theory in which some combinations of the environmental dimensions and organizational structure will lead to better organizational performance. Another finding of this study indicates that the increased level of ownership and control will result in enhancing the level of perceived performance. It should be noted that contingency model-based mode choice would provide managers with the optimal performance because there is not one best performing mode choice in volatile international market. Next, the relationship of market environment with organizational structure was examined through three different perspectives. Market environment was investigated at firm, industry, and national context, which includes five factors -- monitoring uncertainty, asset specificity, cultural distance, political uncertainty, and economic uncertainty. The model is suggestive of a picture in which five environmental factors vie for affecting the choice of market entry modes. All five environmental factors were found to be significantly related to firms' organizational structure. Among five environmental factors, cultural uncertainty has the largest effect on the choice of entry mode followed by monitoring uncertainty, political uncertainty, asset specificity, and economic uncertainty. One of the important implications of this research is the inclusion of franchising as an actual management strategy and competitive business practice that is related to international ownership and control strategy. Higher degrees of uncertainty associated with the foreign market encourage external dependence of the venture, in which the operation depends more heavily on local relationships. Franchising substitutes the loss of ownership by an increase of external relationships and it takes without losing control on retail operation. Resource exploitation depends on the local market for either inputs or outputs for better performance. Understanding the fit between the each set of contingent variables and the elements of ownership and control strategy will allow marketers to determine when franchising is the suitable mode of operation in global markets. Collectively, these results suggest that the choice of an organizational form for international service firms involves a complex balance of firm, industry, and country level factors. Managers can maximize performance by aligning entry mode strategy with external contextual circumstances as well as internal resources. Managers may also be able to make better mode choice decisions using the theory-driven criteria examined in this study, increasing their chances for financial and non-financial success. / Ph. D.

Asthma among children has become an inherent problem in many communities in the United States, especially among the minority population. The South Bronx has a large minority population and a high prevalence of asthma. However, no study to date has explored the factors associated with this high prevalence rates in this population. Drawing from theories of social ecology and environmental health, the objective of this quantitative cross-sectional study is to investigate the correlates of asthma among children in the South Bronx by studying the sociodemographic and environmental risk factors, including parental occupation; neighborhood and housing characteristics, air quality, and poverty. Study participants included parents of 400 children, aged between 4 and 16 years residing in Districts 9 and 10 in the South Bronx. Descriptive, Chi-square statistics, and logistic regression analysis were used to determine the association between exposure constructs and asthma in children. Hypotheses 2 and 3 examined environmental conditions both inside and outside the homes of study participants and determined one factor, the structure of the home to be significantly associated with asthma, while absence of extractor fan when cooking, showed a strong association. This result suggests that only some of the factors indicating conditions inside the homes have a positive association to asthma. This suggests that asthma is not a combined action of both socioeconomic and environmental factors but a result of conditions in the homes. The implication here is that any intervention to asthma has to start in the homes since most children spend their time indoors. This includes creating awareness to risk factors to help develop community based intervention programs that will help reduce occurrence of asthma.