Made available in DSpace on 2015-03-26T13:30:28Z (GMT). No. of bitstreams: 1 texto completo.pdf: 711052 bytes, checksum: bf856a942ed70930176514b90be201c8 (MD5) Previous issue date: 2010-02-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The original vegetation cover of the Zona da Mata Mineira were forests, but today these are restricted to secondary forest remnants, immersed in an agricultural matrix of pasturelands, coffee and Eucalyptus plantations. Even being regenerations, the canopies of these forests may harbor an important part of the original fauna, functioning as a source of biodiversity in these landscapes. Therefore, we supposed that the diversity of herbivorous insects associated to canopy should diminish from the forest interior to the matrix. The objective of this study was to test this assumption, as well as the following explanatory hypotheses for this pattern: insect diversity is determined by resource quantity and quality, environmental heterogeneity, conditions, and predation pressure. We sampled forest fragments immersed in a matrix of Eucalyptus (n = 3) and coffee (n = 3) plantations,along transect from 75m inside the forest up to 75m inside the matrix, in each site. We have chosen these two matrix types as they represent the most abundant agroecossystems with canopy in the region. Insects were classified into chewing and sap-sucking herbivores. In the landscapes with Eucalyptus, both chewing and sap-sucking insects presented an increase in species and individual numbers along the gradient matrix forest. In the landscapes with coffee plantations, there was no response of chewers to the gradient, while sap-sucking species and individual numbers diminished from the matrix to the forest. The habitat components that explained the distribution of chewers were: number of arboreal species, of arboreal strata and of spiders. For sap-suckers, these were leaf density and spider numbers. Therefore, we showed that matrix matrix composed of Eucalyptus and coffee plantations present different permeability for canopy herbivorous insects. Some of the environmental variables explained at least part of the observed patterns in these landscapes: for sap-suckers, leaf density may determine the patterns in both matrix types, because it represents feeding resource availability. For chewers, tree diversity (habitat heterogeneity) and crown volume (resource availability) explained part of the variation in theseorganisms, but were not sufficient to explain the differences between matrix types. We conclude that, at least for chewing herbivores, there are processes at the landscape scale, probably related to locomotion, that are not explained by local habitat variables. Furthermore, our results showed that the two feeding guilds respond at different spatial scales. / A cobertura vegetal original de toda a Zona da Mata Mineira era de florestas, mas hoje está restrita a fragmentos de floresta secundária, imersos numa matriz agrícola de pastagens, cafezais e eucaliptais. Mesmo sendo regenerações, o dossel destas florestas ainda pode abrigar parte importante da fauna original, funcionando como fonte de biodiversidade nestas paisagens. Assim, supomos que a diversidade de insetos herbívoros associados a dossel deve diminuir do interior da floresta ao interior da matriz. O objetivo desse trabalho foi testar esta suposição, e as seguintes hipóteses para explicar este padrão: a diversidade destes insetos é determinada por quantidade e qualidade de recursos; por heterogeneidade ambiental; por condições; e por pressão de predação. Amostramos fragmentos florestais imersos em matriz de eucaliptal (n = 3), e cafezal (n = 3), traçando, em cada local, um transecto desde 75m no interior da matriz até 75m no interior da floresta. Escolhemos estes dois tipos de matriz por representarem os agroecossistemas com dosséis mais abundantes da região. Os insetos foram classificados em herbívoros mastigadores e sugadores. Nas paisagens com eucaliptal, tanto mastigadores quanto sugadores apresentaram aumento do número de espécies e indivíduos ao longo do gradiente matriz - floresta. Nas paisagens com cafezal, não houve resposta de mastigadores ao gradiente, enquanto que número de espécies e de indivíduos de sugadores diminuiu da matriz à floresta. Os componentes do habitat que explicaram a distribuição de mastigadores foram: número de espécies arbóreas, de estratos arbóreos e de aranhas. Para sugadores foram densidade de folhas e número de aranhas. Assim, mostramos que matrizes compostas por eucaliptal ou cafezal têm diferentes permeabilidades para insetos herbívoros associados ao dossel. Algumas das variáveis ambientais explicaram ao menos parte da variação destes insetos nestas paisagens: para sugadores, a densidade de folhas pode determinar os padrões encontrados nos dois tipos de matriz, por representar recurso alimentar. Para mastigadores, a diversidade de árvores (heterogeneidade ambiental) e volume de copa (quantidade de recursos) explicaram parte da variação destes organismos, mas não foram suficientes para explicar as diferenças entre tipos de matriz. Concluímos que, ao menos para herbívoros mastigadores, há processos em escala de paisagem, provavelmente relacionados à locomoção, que não são explicados por variáveis ambientais locais. Além disto, nossos resultados mostraram como as duas guildas respondem a escalas espaciais diferentes.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Bertholletia excelsa H.B.K. is a semi-deciduous species, heliophyle, characteristic of forest land and usually emerging, which collects on the fruits and seeds for use in feed. However, knowledge about the factors that influence the production of the trees is weak. This work aimed to evaluate the influence of rainfall, soil (texture, depth and hydromorphic) dendrometric variables (diameter at breast height and insertion of the crown, tapering, coefficient of taper artificially and taper artificially), qualitative variables (canopy shape and position), competition, sapwood area and size classes and grouping of vessels in the production of fruits and seeds of the species. It was observed that the same number of fruit generate seed yields in kg with significant differences. Rainfall for the month of September shows a positive correlation with the production. The deep soil and with texture sandy clay loam or sandy-clay have a higher yield potential than the shallow and clayey. Trees with less taper (more cylindrical) tended to produce more than trees with greater taper (more conical). Trees with full crowns (circular and irregular) have the same productive potential, and in turn greater potential than those who had half crown. The expected maximum sapwood area decreases exponentially with increasing competition. Trees with sapwood area less than 0.030 m² were not productive and less than 0,075 m² always produce less than 5 kg. Trees that have large solitary vessels are more abundant and have a tendency to produce less than those of other classes. The greatest production potential is expected to trees growing and deep soil, with texture sandy clay loam or clay-sandy, with complete canopies in areas subject to competition for Bertholletia index (IB) below 33, with sapwood area between 0.37450 and 0.29961 square meters and preferably not have large solitary vessels. The proposed model for prediction of seed fresh weight (kg) is Peso=-11.16+0.103636·PPSet +11.699216·galb in soils with texture clayey, in soils with texture sandy clay loam or sandy-clay are level difference with an increase of 7.40 kg of seeds per tree. / Bertholletia excelsa H.B.K. é uma espécie semidecídua, heliófila, característica da mata de terra firme e, normalmente emergente, da qual se coleta os frutos e as sementes para utilização na alimentação. Todavia, o conhecimento sobre os fatores que influenciam a produção de frutos e sementes das árvores é incipiente. Neste trabalho, buscou-se avaliar a influência da precipitação, do solo (textura, hidromorfia e profundidade), variáveis dendrométricas (diâmetro à altura do peito e na inserção da copa, afilamento, coeficiente de forma artificial e forma artificial), variáveis qualitativas (forma e posição de copa), competição, área de alburno e classes de tamanho e agrupamento dos vasos na produção de frutos e sementes da espécie. Observou-se que o número de frutos iguais gera produções de sementes em kg com diferenças significativas. A precipitação do mês de setembro demonstrou correlação positiva com a produção. Os solos profundos e de textura franco argilosa-arenosa ou argilo-arenosa evidenciaram maior potencial produtivo que os rasos e de textura argilosa. Árvores com menor afilamento (mais cilíndricas) revelaram uma tendência a produzirem mais que árvores com maior afilamento (mais cônicas). Árvores com copa completa (circular ou irregular) assinalam mesmo potencial produtivo e, por sua vez, maior potencial que as que apresentam metade da copa. A máxima área de alburno esperada decresce exponencialmente com o aumento da competição. Árvores com área de alburno inferior a 0,030 m² não foram produtivas e as inferiores a 0,075 m² produzem sempre menos de 5 kg. Árvores que possuem vasos largos solitários são mais abundantes e apresentam uma tendência a produzirem menos que as de outras classes. O maior potencial produtivo é esperado para árvores crescendo e solos profundos de texturas francoargilosa- arenosa ou argilo-arenosa, com copa completa, em áreas submetidas à competição pelo Índice de Bertholletia (IB) inferior a 33, com área de alburno entre 0,29961 e 0,37450 m² e preferencialmente não apresentem vasos largos solitários. O modelo proposto para predição do peso fresco de sementes (kg) é: Peso=- 11,16+0,103636·PPSet +11,699216·galb para solos de textura argilosa, em solos de textura franco argilosa-arenosa ou argilo-arenosa há diferença de nível com acréscimo de 7,40 kg de sementes por árvore.

Made available in DSpace on 2016-06-02T18:55:28Z (GMT). No. of bitstreams: 1 6339.pdf: 1320900 bytes, checksum: ceafdc5598f1fbb6c687c57d58657bc1 (MD5) Previous issue date: 2014-08-07 / Universidade Federal de Sao Carlos / The seasonal semideciduous forests from southeastern Brazil have high plant species richness, but have been strongly affected by human interferences, which let them very degraded: nowadays they are represented by small isolated fragments, immersed in a landscape dominated by agriculture and large urban centers. In this sense, the ecology of restoration arises in order to facilitate, accelerate and direct the processes of secondary succession to manage such areas, considering the knowledge about theoretical concepts that aim to review the effectiveness of natural ecosystem management techniques and practices. In such a perspective, we aimed in this experiment to test the following question: During de production of seedlings of the native forest tree species, Ceiba speciosa (Malvaceae) and Handroanthus heptaphyllus (Bignoniaceae), different dilutions of hydrogel associated to irrigation with reused water, could improve their development? To answer this question, we selected three treatments (1g, 4g and 8g of hydrogel), beyond the witness (no hydrogel). The seedlings of both species were irrigated during one month with water reused and water supply. After this period, we estimated the growth of seedlings: roots, height and diameter. We used ANOVA (p = 0.001), and Tukey s test to verify significative differences between the mean of the treatments. We found significative differences in both height and diameter growth from 4g of hydrogel as to C. speciosa as H. heptaphyllus. In relation to the growth of root system of both tree species, the mean of superficial root area differed significantly from 4g of hydrogel when compared to the witness, confirming our initial assumption that the roots would grow in a lower proportion of area because they are in their hydric comfort zone. With such results added to theoretical knowledge in the ecology of restoration, the association of hydrogels with reused water comes to stand up for the sustainable use of water in the irrigation of native seedlings. / Apesar das florestas estacionais semideciduais do interior do estado de São Paulo possuir elevada riqueza de espécies, as interferências humanas deixaram esses ecossistemas degradados e representados por pequenos fragmentos isolados, imersos numa paisagem dominada pela agricultura e centros urbanos. Diante essa problemática, a restauração ecológica surge com o objetivo de facilitar, acelerar e direcionar os processos sucessionais naturais a fim de manejar essas áreas, considerando os novos teóricos da ecologia de comunidades vegetais tropicais, que pretendem revisitar a eficácia de técnicas de manejo em restauração ecológica. Nesta perspectiva, surge como objetivo desse trabalho, testar a pergunta científica: O uso de polímeros hidrogéis em diferentes concentrações na produção de mudas nativas de Ceiba speciosa (Malvaceae) e de Handroanthus heptaphyllus (Bignoniaceae), associados à irrigação com água de reúso tratada, interfere significativamente no crescimento de seu sistema radicular, sua altura e diâmetro, e aumenta a longevidade das mudas? Para responder a essa pergunta, utilizou-se mudas das duas espécies nativas, em três tratamentos (1g, 4g e 8g de hidrogel), além da uma testemunha, contendo apenas o solo. As mudas foram irrigadas por um mês com água de abastecimento e água de reúso tratada; depois de cessadas as irrigações, foram avaliadas os estimadores citados. Foram realizadas análises de variância (p = 0,001), seguidas do teste de Tukey para verificar diferenças significativas entre as médias dos tratamentos. Verificaram-se diferenças significativas no crescimento em altura e diâmetro a partir do uso de 4g de hidrogel, tanto para C. speciosa quanto para H. heptaphyllus. Em relação ao sistema radicular, as médias de área superficial diferiram-se estatisticamente a partir de 4g de hidrogel quando comparadas às testemunhas, tanto para C. speciosa quanto para H. heptaphyllus, confirmando a expectativa inicial de que com hidrogel, as raízes cresceriam em menor proporção em área porque estariam na zona de conforto hídrico. Com esses resultados aliados aos conhecimentos teóricos da ecologia da restauração, a associação de polímeros hidrogéis com água de reúso vem defender a racionalização do uso da água na irrigação de mudas de espécies nativas, reaproveitando águas de reúso que seriam descartadas em águas superficiais.

Orientador: Vera Lex Engel / Banca: Edson José Vidal da Silva / Banca: Raquel Rejano Bonato Negrelle / Resumo: Muitos estudos têm estimado limites de colheita de produtos florestais não-madeireiros (PFNMs) baseados em dados demográficos das espécies fontes. Heliconia velloziana Emygdio (Zingiberales: Heliconiaceae) é utilizada como flor de corte e no paisagismo, e já foi alvo do extrativismo na comunidade rural na região do estudo (Distrito de Taiaçupeba, Mogi das Cruzes, SP). Nosso objetivo geral foi fornecer bases para a elaboração de planos de manejo sustentável para populações silvestres de Heliconia velloziana, através de: avaliação do conhecimento etnobotânico sobre H. velloziana; análise de sua fenologia reprodutiva em relação as variáveis climáticas; avaliação do rendimento e dos efeitos ecológicos do extrativismo sobre taxas vitais de populações silvestres da espécie alvo em diferentes micro-hábitats. Objetivou-se também verificar o potencial para manejo sustentável da espécie e sugerir um regime de rendimento sustentado específico. Para acessar o conhecimento local sobre H. velloziana, foram realizadas entrevistas informais e semiestruturadas, além de observação participante. Os efeitos ecológicos da colheita experimental sobre taxas vitais e a fenologia reprodutiva foram avaliados através de amostragem aleatória estratificada, em uma área total amostral de 0,12ha (12 parcelas de 10x10m) em seis sítios amostrais abrangendo dois estratos (planície e encosta). Em cada sítio, uma população foi submetida à colheita experimental e outra foi mantida como controle. Os aspectos melhor conhecidos pela comunidade local sobre a espécie alvo foram: nome popular, variação intraespecífica, reprodução clonal, visitantes florais, atrativos florais, floração seqüencial, distribuição e abundância local. A espécie foi considerada útil pelos entrevistados para complementação... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Many studies have estimated harvesting limits for non-timber forest products (NTFPs) based on demographic data of the source species. Heliconia velloziana Emygdio (Zingiberales: Heliconiaceae) is used as a cut flower and gardening, and has already been targeted for extractivism by the rural community of the study region. Our general goal was to provide bases for the elaboration of Heliconia velloziana wild populations sustainable management plans, through: assessing ethnobotanical knowledge about H. velloziana; analyzing its reproductive phenology in relation to climatic variables; assessing the yield and ecological effects of harvesting on vital rates of wild populations of the target species in different micro-habitats. We also aimed to verify sustainable management potential of the species and suggest a specific sustained yield regime. To access local knowledge on H. velloziana, informal and semi-structured interviews were done, besides participant observation. The experimental harvesting ecological effects on vital rates and the reproductive phenology were assessed through stratified random sampling, in a total sampling area of 0,12ha (12 10x10m plots) in six sampling sites enclosing two strata (lowland and hillside). At each site, one population was submitted to experimental harvesting and the other was kept as control. The best known aspects by local community about the target species were: common name, intra-specific variation, clonal growth, flower visitors, floral attractants, sequential flowering, local distribution and abundance. The species was considered useful by the interviewed as familiar income complementation through extractivism, besides other secondary uses. It was identified a rich knowledge about the species' management system, once used, that was considered simple and consisted of two to three... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:30:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-09-02Bitstream added on 2014-06-13T19:18:58Z : No. of bitstreams: 1 souza_sexf_me_botfca.pdf: 1158580 bytes, checksum: e01b29e6f87f5b46e937d7e437df136e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Muitos estudos têm estimado limites de colheita de produtos florestais não-madeireiros (PFNMs) baseados em dados demográficos das espécies fontes. Heliconia velloziana Emygdio (Zingiberales: Heliconiaceae) é utilizada como flor de corte e no paisagismo, e já foi alvo do extrativismo na comunidade rural na região do estudo (Distrito de Taiaçupeba, Mogi das Cruzes, SP). Nosso objetivo geral foi fornecer bases para a elaboração de planos de manejo sustentável para populações silvestres de Heliconia velloziana, através de: avaliação do conhecimento etnobotânico sobre H. velloziana; análise de sua fenologia reprodutiva em relação as variáveis climáticas; avaliação do rendimento e dos efeitos ecológicos do extrativismo sobre taxas vitais de populações silvestres da espécie alvo em diferentes micro-hábitats. Objetivou-se também verificar o potencial para manejo sustentável da espécie e sugerir um regime de rendimento sustentado específico. Para acessar o conhecimento local sobre H. velloziana, foram realizadas entrevistas informais e semiestruturadas, além de observação participante. Os efeitos ecológicos da colheita experimental sobre taxas vitais e a fenologia reprodutiva foram avaliados através de amostragem aleatória estratificada, em uma área total amostral de 0,12ha (12 parcelas de 10x10m) em seis sítios amostrais abrangendo dois estratos (planície e encosta). Em cada sítio, uma população foi submetida à colheita experimental e outra foi mantida como controle. Os aspectos melhor conhecidos pela comunidade local sobre a espécie alvo foram: nome popular, variação intraespecífica, reprodução clonal, visitantes florais, atrativos florais, floração seqüencial, distribuição e abundância local. A espécie foi considerada útil pelos entrevistados para complementação... / Many studies have estimated harvesting limits for non-timber forest products (NTFPs) based on demographic data of the source species. Heliconia velloziana Emygdio (Zingiberales: Heliconiaceae) is used as a cut flower and gardening, and has already been targeted for extractivism by the rural community of the study region. Our general goal was to provide bases for the elaboration of Heliconia velloziana wild populations sustainable management plans, through: assessing ethnobotanical knowledge about H. velloziana; analyzing its reproductive phenology in relation to climatic variables; assessing the yield and ecological effects of harvesting on vital rates of wild populations of the target species in different micro-habitats. We also aimed to verify sustainable management potential of the species and suggest a specific sustained yield regime. To access local knowledge on H. velloziana, informal and semi-structured interviews were done, besides participant observation. The experimental harvesting ecological effects on vital rates and the reproductive phenology were assessed through stratified random sampling, in a total sampling area of 0,12ha (12 10x10m plots) in six sampling sites enclosing two strata (lowland and hillside). At each site, one population was submitted to experimental harvesting and the other was kept as control. The best known aspects by local community about the target species were: common name, intra-specific variation, clonal growth, flower visitors, floral attractants, sequential flowering, local distribution and abundance. The species was considered useful by the interviewed as familiar income complementation through extractivism, besides other secondary uses. It was identified a rich knowledge about the species` management system, once used, that was considered simple and consisted of two to three... (Complete abstract click electronic access below)

Human pressure on forest resources increased significantly during the past decades through land use and land use change, especially in the tropics where forest clearing is a major source of CO2 release in the atmosphere. Consequently, forests are the focus of international environmental policies and discussions aiming to reduce emissions from deforestation and forest degradation (i.e. REDD+). The capacity of participating countries to regularly provide accurate forests C stocks measurements at a national scale thus represents an important challenge to address. In dense forests, generally only the above ground biomass (AGB) is measured as it accounts for more than 50% of total C stocks. However, important gaps remain at each scale of measurement, i.e. from felled tree to regional mapping, with the resulting errors propagation through these different scales being probably the most concerning issue.<p><p>In the present work, we propose to address these issues by using a multi-scale approach in order to improve our global understanding of AGB variations in dense tropical forests of Central Africa. In particular, we studied (i) forest AGB prediction from remote-sensing textural analysis, (ii) the potential role of largest trees as predictor of the entire forest-stand AGB and (iii) intra- and inter-individual radial variation of wood specific gravity (WSG, i.e. oven-dry mass divided by its green volume) and its potential consequences on the estimation of the AGB of the tree. <p>First, we analyzed the potential use of textural analysis to predict AGB distribution based on very high spatial resolution satellite scenes. In particular, we used the Fast Fourier Transform Ordination (FOTO) method to predict AGB from heterogeneous forest stands of the Democratic Republic of the Congo (DRC). Here, based on 26 ground plots of 1-ha gathered from the field, plus a successful combination of Geoeye and Quickbird contrasted scenes, we were able to predict and to map AGB with a robust model (R² = 0.85; RMSE = 15%) based on textural gradients. <p>Secondly, the research of AGB indicators was focused on the dissection of the role played by largest trees. Here we found largest trees not only hold large share of forest carbon stock but they contain the print of most of forest-stand structure and diversity. Using a large dataset from western Cameroon to eastern DRC, we developed a non-linear model to predict forest carbon stock from the measurement of only a few large trees. We found the AGB of the 5 % largest stems allow to predict the AGB of the entire forest-stand yielding an R² of 0.87 at a regional scale. Focusing on largest trees species composition, we also showed only 5 % of species account for 50 % of total AGB.<p>In the end, we investigated inter- and intra-individual WSG variations. Despite recognized inter- and intra-specific variations along the radial axis, their ecological determinants and their consequences on trees aboveground biomass assessments remain understudied in tropical regions. To our knowledge, it has never been investigated in Africa. Using a 3-D X-Ray scanner, we studied the radial WSG variation of 14 canopy species of DRC tropical forests. Wood specific gravity variance along the radial profile was dominated by differences between species intercepts (~76%), followed by the differences between their slope (~11%) and between individual cores intercept (~10%). Residual variance was minimal (~3%). Interestingly, no differences were found in the comparison of mean WSG observed on the entire core and the mean WSG at 1-cm under the bark (intercept ~0; coefficient = 1.03). In addition, local values of WSG are strongly correlated with mean value in the global data base at species level. <p><p>I deeply believe these results favor the development of promising tools to map and to estimate accurately the AGB of tropical forest-stands. The information provided by largest trees on the entire forest-stand is particularly interesting both for developing new sampling strategies for carbon stocks monitoring and to characterize tropical forest-stand structure. In particular, our results should provide the opportunity to decrease current sampling cost while decreasing its main related uncertainties, and might also favor an increase of the current sampling coverage. <p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

A descrição de padrões, i.e., tendências ou arranjos não aleatórios em comunidades, possui um longo histórico em ecologia vegetal. Comumente, a estrutura e diversidade de comunidades vegetais são descritas a partir de sua distribuição em classes de tamanho (SDD), distribuição espacial (SSD) e de sua distribuição abundância de espécies (SAD). Isto porque há um pressuposto de que padrões existentes nestes descritores de comunidades são assinaturas de processos fundamentais na sua organização e funcionamento. Assim, a descrição de padrões é com frequência o primeiro passo para gerar ou testar hipóteses sobre esses processos que regulam a estrutura e diversidade de comunidades. Organizada em diferentes capítulos, esta tese teve como objetivo central descrever e comparar padrões em diferentes comunidades arbóreas Neotropicais, buscando gerar hipóteses sobre os processos que regulam sua organização e funcionamento. Para tanto, buscou-se utilizar uma abordagem de inferência baseada no ajuste e seleção de modelos, que foi realizado usando máxima verossimilhança estatística. Em todos os capítulos, os dados sobre as comunidades arbóreas são oriundos de diferentes parcelas florestais permanentes, quatro delas com 10,24 hectares, localizadas no Brasil, e outra com 50 hectares, localizada no Panamá. Além da introdução geral sobre os conceitos e técnicas utilizadas nesta tese (Capítulo 1), foram avaliados e comparados: (i) os descritores básicos da estrutura florestal (i.e. abundância, área basal e riqueza de espécies por sub-parcela - Capítulo 2); (ii) a SAD e como ela varia com o aumento da escala e tamanho amostral (Capítulo 3); (iii) a SDD e como ela se relaciona com a demografia das espécies (Capítulo 4.1 e 4.2); e, por fim, (iv) a SSD e como ela varia entre parcelas permanentes (Capítulo 5). Apenas a relação entre a SDD e a demografia das espécies foi realizada como os dados da parcela panamenha, enquanto que os demais capítulos se referem as quatro parcelas brasileiras. Cada capítulo utilizou métodos e modelos probabilísticos distintos para a descrição e comparação das variáveis de interesse. O Capítulo 2 mostrou que os descritores básicos florestais foram muito diferentes entre as quatro parcelas brasileiras. Estes descritores foram raramente normais nas escalas estudadas e as diferenças entre as parcelas foram mais evidentes quando a variância é considerada, fornecendo informações extras sobre os processos geradores de variabilidade dentro das parcelas. O Capítulo 3 mostrou que a mudança no formato da SAD com o aumento da escala é predominantemente um efeito indireto do tamanho da amostra. Assim, pode haver um efeito de escala, mas esse efeito é pequeno e parece depender do grau de similaridade de espécies entre amostras. No capítulo 4.1, foi necessária uma combinação de quatro diferentes distribuições de probabilidade para descrever a ampla gama de SDD, visto que os modelos candidatos raramente foram adequados para a maioria das espécies. No capítulo 4.2, verificou-se que o crescimento e recrutamento determinam o formato da SDD, o que não aconteceu com a mortalidade. No geral, curvas decrescentes de crescimento por diâmetro (i.e., maior crescimento juvenil) levaram à SDD menos íngremes, enquanto que taxas altas de recrutamento estiveram relacionadas à SDD mais íngremes. Apesar das previsões da teoria de equilíbrio demográfico terem apresentado relações positivas com as SDD observadas, houve muita variação, fazendo com que as previsões fossem pouco confiáveis. No capítulo 5, confirmou-se que a grande maioria das espécies se distribui de maneira agregada no espaço. No entanto, as parcelas apresentaram diferentes padrões de intensidade e tamanho de agregação. As diferenças nestes padrões entre parcelas foram, em geral, similares àquelas encontradas ao comparar populações de uma mesma espécie entre parcelas. Assim, as parcelas permanentes brasileiras apresentaram padrões bem distintos umas das outras, tanto em termos de estrutura quanto de diversidade de espécies, padrões estes que provavelmente foram determinados pelas condições ambientais as quais estas comunidades estão sujeitas. Diferentes padrões também foram encontrados em relação à distribuição espacial das espécies (i.e. frequência, intensidade e tamanho de agregação). Contudo, os resultados sugeriram que estes padrões estiveram mais ligados a heterogeneidade ambiental interna das parcelas do que com condições de clima e solo as quais estas comunidades estão sujeitas. Por outro lado, os padrões de distribuição espacial das espécies parecem ter influenciado os padrões de diversidade das comunidades. Não houve, entretanto, um número suficiente de parcelas sob as diferentes combinações de condições ambientais para testar estas sugestões ou para fazer generalizações para cada formação florestal, sendo necessário o confronto destas sugestões com outros estudos realizados em condições similares. Já na parcela panamenha, foi confirmada a expectativa teórica de que distribuições diamétricas refletem a demografia das espécies, em especial os padrões de crescimento e recrutamento. Mas, houve grande variação entre as espécies, dificultando a inferência precisa de padrões demográficos passados das espécies a partir de SDD atuais. Por fim, a abordagem analítica baseada no ajuste e seleção de modelos por máxima foi uma alternativa viável, flexível e apropriada, principalmente em relação à comparação simultânea de diferentes modelos e à busca de processos por trás dos padrões encontrados. Apesar de algumas limitações de cunho operacional, a abordagem baseado em modelos é uma alternativa adequada para a descrição de comunidades arbóreas, podendo ser utilizada de maneira consorciada com outras abordagens (e.g. testes de hipóteses) para descrever padrões e para gerar ou testar hipóteses sobre esses processos fundamentais que regulam a estrutura e diversidade destas comunidades. / Pattern description - search for trends or non-random arrangements in communities, has a long history in plant ecology. Commonly, the structure and diversity of plant communities are described based on their size class distribution (SDD), spatial distribution (SSD) and species abundance distribution (SAD). This is because there is an underlying assumption that the existing patterns in these community descriptors are signatures of key processes determining their organization and functioning. Thus, pattern description is often the first step to generate or test hypotheses about the processes governing community structure and diversity. Organized in different chapters, the main goal of this thesis was to describe and compare different patterns in Neotropical tree communities and to generate hypotheses about the processes that regulate them. To do so we used an approach based on model selection, which was performed using maximum likelihood. In all chapters the data on tree communities came from different permanent forest plots, four of them of 10.24 ha located in Brazil and another 50 ha located in Panama. In addition to the general introduction of key concepts and techniques used along the thesis (Chapter 1), it was evaluated and compared: (i) the basic forest descriptors (i.e. abundance, basal area and species richness per subplot - Chapter 2), (ii) the SAD and how it varies with increasing sample size and scale (Chapter 3), (iii) the SDD and how it relates to species demography (Chapter 4.1 and 4.2) and, finally, (iv) the SSD and how it varies between plots (Chapter 5). Only the relationship between SDD and species demography o was performed using the Panama plot data, while the remaining chapters relate the four Brazilian plots. Each chapter used different methods and probabilistic models for the description and comparison of the variables of interest. In Chapter 2, it was found that basic forest descriptors were very different between the four Brazilian plots. These descriptors were rarely normal at the studied scales and differences between plots were more evident when variance is accounted for, which seems to provide information on processes generating within-plot variability. Chapter 3 showed that the change in shape of the SAD due to increasing scale is predominantly an indirect effect of sample size. Thus, there may be an effect of the scale, but this effect is minor and seems to depend on the degree of species turnover between samples. In Chapter 4.1, it was shown that the combination of four different probability distributions was necessary to describe the wide range of SDD, since models were rarely appropriate for the majority of tree species. In Chapter 4.2, it was found that growth and recruitment, but not mortality, shape the SDD. On average, decreasing growth-diameter curves (i.e. higher juvenile growth) were associated to less steep SDD, whereas high recruitment rates were related to steeper SDD. Although the predictions of demographic equilibrium theory were positively related to the observed SDD, there was lots of variation, making predictions quite unreliable. In Chapter 5, it was confirmed that the great majority of species had clumped spatial distributions. However, the results of intensity and size of clumps showed that the patterns of aggregation were different among plots. Species shared between two plots generally showed patterns of spatial distribution that matched the patterns found for individual plots. Therefore, the Brazilian plots presented very distinct patterns, both in terms of structure and species diversity, which were most probably determined by the environmental conditions to which these communities are subjected. Different patterns among plots were also found in respect to species spatial distribution (i.e. frequency, intensity and size of aggregation). However, the results suggested that these patterns were more connected to within-plot environmental heterogeneity than with climate and soil conditions. On the other hand, the spatial distribution of the species seems to have influenced the patterns of diversity of communities. There was not, however, a sufficient number of plots under different combinations of environmental conditions to test these suggestions or to make generalizations for each forest type, being necessary to confront these suggestions with other studies conducted in similar conditions. In the Panamanian plot, it was confirmed the theoretical expectation that diameter distributions reflect the demographics of the species, in particular the patterns of growth and recruitment. But there was great variability among species, making it difficult to infer past demographic patterns from current SDD. Finally, the analytical approach based on model fit and selection by maximum likelihood was a viable, flexible and appropriate approach, particularly in respect to the simultaneous comparison of different models and to the search for mechanisms underlying patterns. Despite some more operational limitations, the model-based approach is an appropriate alternative for the description of tree communities and can be jointly used with other approaches (e.g. hypothesis testing) for pattern description and to generate and test hypotheses on the fundamental processes that determine the structure and diversity of these communities.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-07-25T11:29:35Z No. of bitstreams: 1 thiagorubiolidafonseca.pdf: 2521373 bytes, checksum: a24da2c1e7f75a55e9c0a3bb75fc040e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-07-25T16:32:43Z (GMT) No. of bitstreams: 1 thiagorubiolidafonseca.pdf: 2521373 bytes, checksum: a24da2c1e7f75a55e9c0a3bb75fc040e (MD5) / Made available in DSpace on 2016-07-25T16:32:44Z (GMT). No. of bitstreams: 1 thiagorubiolidafonseca.pdf: 2521373 bytes, checksum: a24da2c1e7f75a55e9c0a3bb75fc040e (MD5) Previous issue date: 2016-03-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / As florestas urbanas estão inseridas em uma matriz altamente antropizada e fragmentada, resultando em comunidades com diferentes arranjos bióticos e estruturais. Uma das principais consequências dos impactos antrópicos, intensificados durante o Antropoceno, foi o surgimento dos Novel Ecosystems. Considerando a importância das florestas urbanas para a manutenção de serviços ecossistêmicos, conservação da biodiversidade, bem estar humano e sua relação com o conceito de Novel Ecosystems, três perguntas foram elaboradas: (1) Fragmentos florestais urbanos, localizados próximos entre si, apresentam diversidade, estrutura e composição de espécies semelhantes? (2) Fragmentos florestais urbanos apresentam composição, diversidade e estrutura distintas de uma floresta secundária em estágio avançado de regeneração, de mesma fitofisionomia na região? (3) Os fragmentos florestais urbanos estudados são exemplos de Novel Forests no Brasil? O estudo foi realizado no sudeste de Minas Gerais, em predomínio de Floresta Estacional Semidecidual Montana. Os indivíduos arbóreos (DAP ≥ 5 cm) de cinco fragmentos florestais urbanos e um fragmento florestal em estágio avançado de regeneração (controle) foram amostrados em 10 parcelas de 20 x 20 m. Os fragmentos urbanos se diferenciaram entre si com relação à diversidade e composição de espécies, devido à dominância de espécies exóticas (Pinus elliottii Engelm.) e nativas oportunistas (Eremanthus erythropappus (DC.) MacLeish). Os fragmentos urbanos se diferenciaram da floresta controle, apresentando composição de espécies distinta, baixa acumulação de biomassa, baixa diversidade e distribuição de espécies menos heterogênea, em sua maioria. A dominância de poucas espécies (exóticas ou nativas oportunistas) foi suficiente para indicar a ultrapassagem de um limiar ecológico, classificando-os como Novel Forests. Devido à atualidade do conceito e a escassez de trabalhos no Brasil, este estudo é importante para documentar a existência de Novel Forests em território brasileiro e contribuir para o conhecimento do seu funcionamento. / Urban forests are within a highly anthropogenic and fragmented matrix, resulting in communities with distinct biotic and structural assemblages. The most important consequence of human impacts, which was intensified in the Anthropocene, was the arise of Novel Ecosystems. Given the importance of urban forests to maintain ecosystem services, biodiversity conservation, human welfare and its relation with Novel Ecosystem concept, three questions were developed: (1) Diversity, structure and species composition are similar in urban forest fragments, located close together? (2) Species composition, diversity and structure of urban forest fragments are distinct from an old-growth forest located within the same phytophysiognomy and same region? (3) Are the studied urban forest fragments examples of brazilian Novel Forests? The study was conducted in the southeast of Minas Gerais State, within the seasonally semideciduous domain. Trees (DBH ≥ 5 centimeter) of five urban forest fragments and one old-growth forest fragment (control) were sampled with 10 plots of 20 x 20 m. The results showed that urban forest fragments were different mainly between diversity and species composition, due to the dominance of alien species (Pinus elliottii Engelm.) and native opportunists (Eremanthus erythropappus (DC.) MacLeish). The urban forest fragments were different from the control forest due to mostly different species composition, low biomass accumulation, low diversity, and less heterogeneous species distribution. The dominance of a few species (exotic or native opportunists) in most of the urban forest fragments was sufficient to indicate a crossed ecological threshold and define them as Novel Ecosystems. Due to the novelty of the concept and lack of studies in Brazil, this is important to show the existence of Brazilian Novel Forests and contribute to the knowledge of their function.

Le maintien de ressources génétiques suffisamment larges est nécessaire pour assurer la viabilité et le potentiel évolutif des populations naturelles. Cette thèse a le principal objectif de caractériser la diversité et la variabilité génétique chez le genre Virola (Myristicaceae) pour décrire les processus évolutifs qui en sont à l'origine. Premièrement,une étude de la régénération d'un échantillonnage exhaustif de V. michelii a été menée dans une parcelle du dispositif expérimental de Paracou ayant subi une exploitation forestière de faible intensité et comparée à une parcelle témoin. La diversité génétique mesurée à partir de marqueurs AFLP (Amplified Fragment-Length Polymorphism, N=229) en zones perturbées s'est révélée être plis grande qu'en zone non-perturbées. Puis, l'adaptation locale a été étudiée à travers ces mêmes individus et certains loci (AFLP) montrent une sélection divergente pour des environnements contrastés, indiquant un signe d'adaptation. Enfin, l'étude des niveaux de divergence génétique chez trois espèces de Virola du bouclier guyanais (V. michelii, V. surinamensis et V. kwatae) montrent que deux d'entre elles (V. surinamensis et V. kwatae) montrent de fortes similarités génétiques malgré leur distribution sur des environnements contrastés. des Flux de gènes intersécifiques ont été mis en évidence chez ces deux espèces-soeurs et l'hypothèse d'une spéciation écologique est avancée. Ce travail a permis d'aborder différents processus évolutifs à l'origine de la diversité génétique actuelle chez ces espèces forestières tropicales et peut fournir une contribution pour appréhender le devenir des populations. / Genetic diversity is an essential component of biodiversity. The maintenance of sufficient genetic resources is needed to ensure the adaptive potential and the viability of natural populations. In the current context of global changes, the study of adaptation in living organisms is a key task, particularly for tropical forest trees that are dominant components (in terms of biomass and as ecological drivers) of some of the most diverse ecosystems on Earth. The main objective of this thesis is to characterize genetic diversity and genetic variability to understand the evolutionary processes that act on them. This ecological-genetic study was carried out at the interspecific and intraspecific level in the Virola genus.If overall high levels of genetic diversity are a guarantee of prosperity for the future of the species, it seems essential to perform studies on the impact of environmental disturbance on genetic diversity. In the first section, the genetic consequences of regeneration dynamics were studied in an exhaustive sample of V. michelii in a low-intensity logging plot and in a control plot at the Paracou experimental site. A greater genetic diversity, measured from AFLP markers (Amplified Fragment Length Polymorphism, N = 229), was found in perturbed areas. Because studying genetic diversity within species may be useful for understanding species adaptation to environmental changes, in the second section. I studied local adaptation in a population of V. michelii on the Paracou experimental site. A genome scan approach with AFLPs (N = 229) was conducted on 77 adult individuals and 401 juveniles to identify genetic differences between populations associated to contrasting conditions for an array of environmental variables. Some loci (N = 2) were found to be subject to divergent selection, indicating adaptation to contrasting habitats.In the third section, the study of levels of genetic divergence in three Virola species of the Guiana Shield (V. michelii, V. surinamensis and V. kwatae) was investigated for nuclear and chloroplast molecular markers. V. surinamensis and V. kwatae showed strong genetic similarities despite their contrasting habitats preferences. Coalescent analyses have revealed, on one hand, a recent divergence between these two species suggesting an ecological speciation, and one the other hand that interspecific gene flow occurs between these sister-species.This work focuses on understanding evolutionary processes shaping genetic diversity and provides a useful contribution for biodiversity conservation programs.

In tropical forests, ants are numerous, diversified and ecologically important, being present from forest floor to upper canopy and exploiting a wide variety of diets. Nearly half of the ant species are directly in contact with the ground stratum, including the leaf-litter and the underlying soil, for nesting or foraging. The main factors known to influence ant distribution and abundance can be environmental (e.g. heterogeneous distribution of microhabitat size, nutrient availability, microclimate, soil properties) or biotic (e.g. inter- and intraspecific competition, prey availability). Some of these factors, such as leaf-litter volume or prey availability, may also vary seasonally. Also, the Ecuadorian Andes are known as being a hotspot of biodiversity for a large array of organisms, but it was not documented until now if this is also the case for ants.<p><p>The general aim of the PhD project was to identify, by both descriptive and experimental approaches, the factors determining the structure of a ground-dwelling ant assemblage at a small-spatial scale and its temporal variation in an evergreen premontane tropical forest of the Ecuadorian Andes.<p><p>In the descriptive part of the project, we studied both horizontal (along a transect) and vertical (across ground layers) species diversity and distribution of ground-dwelling ants. To attempt to explain the observed patterns, we measured a series of environmental factors varying at small spatial scale and/or seasonally: canopy openness, leaf-litter quantity, slope, and a series of soil physico-chemical properties (e.g. texture). The ant assemblage richness appeared to be at least as high as in the Amazonian Basin, with up to 33 species per m². The heterogeneity of species spatial distribution at small spatial scale was high, with distinct species composition (average Jaccard index = 0.2 ± 0.08 SD) and abundance (up to 40 fold) in contiguous plots. We observed a strong seasonal effect on the ant assemblage structure. The higher ant diversity and abundance found at the surface and in the mineral soil during the dry season suggested a seasonal peak of activity on the ground surface and the seasonal migration of drought-sensitive species downwards in the soil. Ant diversity was related to distinct environmental factors according to the ground layer considered. We found strong correlations between litter amount and dominant ant distribution in the leaf-litter layer, while we found no correlation with any factor in the soil layer. The low amount of negative association between dominant species suggested a low interspecific competition.<p><p>In the experimental part of the project, our aim was to identify experimentally the relative importance of habitat size vs. prey availability in structuring the leaf-litter ant assemblage. We studied the response of various ant trophic groups to an increased nutrient availability which boosted the decomposition of their leaf-litter habitat and enhanced the abundance of their prey. Bottom-up effect on the ant fauna (and other predaceous arthropods) regarding species composition and dominance was also studied. Stable isotope analysis was used to distinguish trophic groups among ants and mesofauna. Ants responded differentially according to their trophic group: despite increased prey availability, predatory species were negatively affected by nutrient supply, while other ant trophic group densities did not change. Our results showed that predatory ants are limited by habitat size rather than by prey availability, and that these ants are more affected by habitat loss than their prey, other ant trophic groups and other macrofauna taxa. Furthermore, a taxonomic shift occurred within each ant trophic group, leading to the replacement of dominant genera in fertilized plots.<p><p>As a conclusion, our results emphasize the importance of distinguishing layers among the ground matrix, since both ant faunas and their response to environmental factors vary vertically and seasonally. The distribution of ground-dwelling ants was only weakly explained by both the environmental factors measured and by biotic interactions, at a small spatial scale. Also, our results emphasize the importance of distinguishing trophic groups among the ant assemblage, since the response of these groups under changing conditions was different. In this regard, stable isotope analysis was a useful tool for investigating the trophic ecology of various leaf-litter taxa, and it was successfully used for the first time to assess the diet of leaf-litter ants and their position in the Brown Food Web relative to other taxa. Also, the isotopic approach allowed us to increase the knowledge about the biology of a rare and cryptic ant species, by revealing its top-predatory position. The outstanding local species richness that we observed confirms that the Ecuadorian Andes are also a biodiversity hotspot for ants. / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished