Made available in DSpace on 2016-06-02T19:31:36Z (GMT). No. of bitstreams: 1 DissKGM.pdf: 564144 bytes, checksum: 6b591c0ae516731c5cece36f0e7e31ed (MD5) Previous issue date: 2006-02-20 / The Cerrado Domain is the second largest Brazilian phytogeographic province, occupying originally 23% of Brazil s land surface, under seasonal climate. The cerrado presents a floristic and physiognomic variation, ranging from grassland to tall woodland. Anemochorous species are proportionally more important in the cerrado than in Brazilian rain forests, especially in open physiognomies. Morphological designs of wind-dispersed diaspores appear to slow their rates of descent, increasing their chances of exposure to winds and of reaching safe sites to germinate. Wind-dispersed species are constrained to fruit during the best time for seed dispersal. Also, the height of seed release and surrounding vegetation are fundamental to long-distance dispersal. We selected the wind-dispersed species from three phytosociological surveys (disjoint and core sites) and classified them into autogyro, rollingautogyro, floater, or undulator, according to the diaspore morphology and aerodynamic behavior in still air. For each species, we had data on its fruiting period. We tried to assess whether there was a seasonality and, if there was, whether it was synchronized with some climatic conditions. The number of fruiting anemochorous cerrado species was highest at the dry season, coinciding with reduced precipitation. Next, we studied the anemochorous diaspore spectra and index of divergence from species to anemochorous diaspore diversity (IDD) in three cerrado physiognomies (campo cerrado, cerrado sensu stricto, and cerradão) in a disjoint site and three cerrado physiognomies (cerrado sensu stricto) in different floristic pronvinces. There was a floristic unit among the cerrado physiognomies, with the ecotonal ones containing both grassland and woodland elements. Both nuclear and disjoint sites were ecologically similar regarding the species distribution. However, there were differences when species abundances were considered. In denser sites, vegetation reduces wind velocity in ... / O Domínio do Cerrado é a segunda maior região fitogeográfica brasileira, originalmente cobrindo 23% do território brasileiro, sob influência de clima estacional. O cerrado apresenta variação florística e fisionômica, indo desde uma fisionomia campestre até uma florestal. Espécies anemocóricas são proporcionalmente mais importantes no cerrado do que em florestas tropicais, especialmente em fisionomias mais abertas. As características morfológicas dos diásporos anemocóricos parecem diminuir suas razões de descida, aumentando a chance de exposição aos ventos e de encontrar locais seguros para germinar. Espécies anemocóricas tendem a frutificar na melhor época para dispersar suas sementes. Também a altura de liberação e a vegetação circundante são fundamentais para a dispersão à longas distâncias. Selecionamos as espécies anemocóricas de três levantamentos fitossociológicos, um realizado em área nuclear, dois em área disjunta, e as classificamos em autogiro, autogiro-rotativas, flutuantes e planadoras, de acordo com a morfologia e comportamento do diásporo no ar parado. Tínhamos o período de frutificação para cada espécie anemocórica de uma área disjunta e tentamos observar a existência de estacionalidade na frutificação e a relação desta com algumas variáveis climáticas. O número de espécies frutificando foi maior na estação seca, coincidindo com o período de menores pluviosidade e umidade relativa do ar. Depois, estudamos os espectros de diásporos anemocóricos e os índices de divergência de diversidade (IDD) de espécies a tipos de diásporo anemocórico de três fisionomias do cerrado (campo cerrado, cerrado sensu stricto e cerradão) em uma área disjunta; e de três fisionomia de cerrado (cerrado sensu stricto) em províncias florísticas diferentes. Além de haver uma unidade florística na área disjunta, com a fisionomia ecotonal contendo elementos campestres e florestais, as áreas nuclear e disjuntas foram ecologicamente ...

Dispersal, especially long-distance dispersal, is an important component in many disciplines within biology. Many species are passively dispersed by wind, not least spore-dispersed organisms. In this thesis I investigated the dispersal capacity of bryophytes by studying the colonization patterns from local scales (100 m) to landscape scales (20 km). The dispersal distances were measured from a known source (up to 600 m away) or inferred from a connectivity measure (1–20 km). I introduced acidic clay to measure the colonization rates over one season of a pioneer moss, Discelium nudum (I–III). I also investigated which vascular plants and bryophytes that had colonized limed mires approximately 20–30 years after the first disturbance (IV). Discelium effectively colonized new disturbed substrates over one season. Most spores were deposited up to 50 meters from a source but the relationship between local colonization rates and connectivity increased with distance up to 20 km (I–III). Also calcicolous wetland bryophyte species were good colonizers over similar distances, while vascular plants in the same environment colonized less frequently. Common bryophytes that produce spores frequently were more effective colonizers, while no effect of spore size was detected (IV). A mechanistic model that take into account meteorological parameters to simulate the trajectories for spores of Discelium nudum fitted rather well to the observed colonization pattern, especially if spore release thresholds in wind variation and humidity were accounted for (III). This thesis conclude that bryophytes in open habitats can disperse effectively across landscapes given that the regional spore source is large enough (i.e. are common in the region and produce spores abundantly). For spore-dispersed organisms in open landscapes I suggest that it is often the colonization phase and not the transport that is the main bottle-neck for maintaining populations across landscapes. / <p>At the time of the doctoral defence the following papesr were unpublished and had  a status as follows: Paper 2: Epubl ahead of print; Paper 3: Manuscript; Paper 4: Manuscript</p>

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Tropical dry forests are presented with great biological diversity and studies on the dispersion mechanisms and seed rain provide valuable information on dispersion standards, entrances and exits of seeds that act in the process of natural regeneration in preserved and/or degraded environments, as well as in the abundance, spatial distribution, density and species richness. Therefore, this study aims to identify strategies for the establishment of plant species according to the to the dispersal syndroms and characterize the seed rain in a remnant of Caatinga in the city of Porto da Folha, Semiarid of Sergipe, relating it to the dry and rainy season, in order to provide a better understanding of the interactions and dynamics of the place. For quali-quantitative evaluation of the present seed rain in the area, 25 collectors (confectioned in wood) were installed at 50cm above of the ground. The collectors were square shaped with a sample area of 1m2 with a depth of 10cm, and shading screen covering the bottom. The evaluations were performed monthly during 11 months. 4248 seeds belonging to 40 taxons were counted, from which 28 were identified to species level, four to genus and 12 classified as indeterminate. The identified species belong to 17 botanical families and are composed for four vegetation habits: trees, shrubs, herbs and lianas. The syndrome of predominant dispersion in the area, considering the number of identified species, was the ballistic dispersal (32,5%), followed of the anemochory (20%) and the zoochory (17,5%). As for the seeds density, the predominant dispersion syndrome found was anemocory (34,7%), exceeding the autocory (31,5%) and the zoochory (4,3%). The seed rain acts effectively in the self-regeneration of the vegetal community, due to the wealth and abundance of seeds deposited during the evaluation months, favoring the responsible mechanisms for the succession dynamics, in addition to contributing in the conservation and recovery of areas next to the observed forest fragment or other modified areas of Caatinga. / As florestas tropicais secas apresentam uma grande diversidade biológica e estudos sobre os mecanismos de dispersão e chuva de sementes proporcionam informações valiosas sobre padrões de dispersão, entradas e saídas de diásporos que atuam no processo de regeneração natural em ambientes preservados e/ou degradados, assim como na abundância, distribuição espacial, densidade e riqueza de espécies. Portanto, objetivou-se com a realização deste estudo identificar as estratégias de estabelecimento de espécies vegetais quanto às síndromes de dispersão e caracterizar a chuva de sementes em um remanescente de Caatinga localizado no município de Porto da Folha, Semiárido sergipano, relacionando-a com o período seco e chuvoso, visando uma melhor compreensão das interações aí existente e sua dinâmica. Para a avaliação quali-quantitativa da chuva de sementes presente na área foram instalados 25 coletores (confeccionados em madeira), a 50cm acima do solo. Os coletores apresentavam formato quadrado com área amostral de 1m2, com 10 cm de profundidade, sendo utilizado no fundo destes tela sombrite. As avaliações foram realizadas mensalmente durante 11 meses. Foram contabilizadas 4.248 sementes, pertencentes a 40 táxons, dos quais foram identificados 28 ao nível de espécie, quatro ao nível de gênero e 12 classificados como indeterminados. As espécies identificadas pertencem a 17 famílias botânicas e são compostas por quatro hábitos vegetacionais: árvores, arbustos, herbáceas e lianas. A síndrome de dispersão predominante na área, considerando-se o número de espécies identificadas, foi a autocoria (32,5%), seguida da anemocoria (20%) e a zoocoria (17,5%). Quanto à densidade de deposição de sementes, a síndrome de dispersão predominante foi anemocoria (34,7%), sendo superior à autocoria (31,5%) e à zoocoria (4,3%). A chuva de sementes atua efetivamente na autoregeneração da comunidade vegetal, em virtude da riqueza e abundância de sementes depositadas durante os meses de avaliação, favorecendo os mecanismos responsáveis pela dinâmica de sucessão, além de contribuir na conservação e reabilitação de áreas próximas ao fragmento florestal observado ou outras áreas de Caatinga alteradas.

Several methods are used for studying seed dispersal (seed traps, tracking individual seeds, tracking seeds coloured by fluorescent colours, etc.) However, only a few studies compared results obtained by several methods. In first part of this master thesis, I compared the three above mentioned methods used for studying seed dispersal using species from Asteraceae family. From previous research within the study area (Úštěcko), it is known that dry grassland species are able to colonize abandoned fields. Using seed dispersal data obtained within this theses, I tried to assess the role of seed dispersal on distribution of dry grassland species on abandoned fields both on local and regional scale. The results showed that dispersal curves obtained by the three methods differ significantly. This results may be due to different wind conditions during the experiments. Seed trap data show results from long-term seed dispersal influenced by highly variable wind conditions. In contrary, seed release experiments showed results based on single dispersal event under limited wind conditions. Tracking seeds coloured by fluorescent colours was shown to be not convenient for small seeds, but I can recommend this method for larger seeds. Influence of seed dispersal ability on abundance of dry grassland species on...

Long-distance dispersal of Rumex alpinus was studied in the Giant Mountain in the National Park. The invasion of R. alpinus is there kind of problem. The work builds on a thesis from year 2007 (20007 Červenková), in which was made the model of the invasion of R. alpinus in the area of the Giant Mountain. The measurements of the seeds spread take place at four localities, three of them were for measuring of water dispersal and one was for measuring of winter dispersal. Anemochory was measured using traps in the meadow up to a distance of 50 m. The seeds were dispersed by wind to a distance of 20 meters. Hydrochory was measured using a network's traps in the streams up to 100 m. The largest measured water dispersal was 100 m. Hydrochory therefore proved to be an important factor, which influenced the invasion of R. alpinus. The storms and flood had the great influence on the hydrochory and anemochory. The prediction exponential curves were compiled from the data about the wind dispersal. The curves express the spread to more than a measured distance. The field dispersion curves were compared with theoretical curves, which were used in the model of the invasion from 2007. It turned out that the theoretical curves overestimate the spread of R. alpinus by wind. The dispersion of seeds was underestimated in the...

Many plant species are closely related to river biotopes or to biotopes influenced by rivers. River systems create important linear corridors in ecosystems and directly or non-directly influence spatial spread of species in these environments. This offer many questions about species spread in this system. We can answer these questions by using molecular methods. Using 10 microsatellite (SSRs) primers, 202 individuals of Phragmites australis from 60 populations were analysed. Those analyses allowed reveal kinship of individuals, obtain information about spatial spread of populations and about spreading of common reed. Phragmites australis creates both - monoclonal and polyclonal - populations. Dependence of rate of clonality on environment was revealed. Populations from river banks are more monoclonal, populations from pond shores are more polyclonal. Populations are isolated. The highest percentage of variability was explained on among-population level. This is common for anemochoric species. Communication between populations is present, more on shorter distances. Evidence for vegetative spread was found on short distance. Generative spread is much more common. Long-distance spreading is mediated by generative diaspores - seeds. This spreading includes within-river spread, among-river spread and spreading...