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Orientador: Flavio Antonio Maes dos Santos / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-06T06:40:59Z (GMT). No. of bitstreams: 1 Bertani_DanielaFessel_D.pdf: 1391757 bytes, checksum: 4a292a79ba5055a63f784b0a84944743 (MD5) Previous issue date: 2006 / Resumo: Existe muita variação no grau de sensibilidade de populações de plantas à diminuição de habitats naturais e poucos estudos em áreas com prioridade de conservação.Este estudo teve como objetivo testar se a descontinuidade e qualidade de habitats de Mata Atlântica afetam a abundância, estrutura, relações alo métricas, dinâmica e germinabilidade de sementes de populações de uma espécie comum de sub-bosque, P_ychotria suterella (Rubiaceae). Foram amostradas nove populações dessa espécie em três áreas em uma floresta contínua, três tTagmentos conectados e três tTagmentos isolados em uma paisagem de Mata Atlântica tTagmentada no estado de São Paulo. A densidade de indivíduos foi menor e a taxa de mortalidade maior nos tTagmentos isolados. Todas as populações apresentaram padrão espacial agrupado, exceto a população de um fragmento isolado, que apresentou distribuição aleatória. As populações de menor tamanho apresentaram maior crescimento em altura e diâmetro, maior taxa de mortalidade e maior taxa de ingresso. Diferenças nas taxas de ingresso entre populações aparentemente não tiveram relação com a germinabilidade de sementes, pois a porcentagem de germinação não diferiu entre populações. A mortalidade aumentou em função do aumento da densidade intraespecífica. o crescimento negativo aumentou com o aumento da porcentagem de danos nos indivíduos. Indivíduos de classes de tamanho diferentes parecem ter sido afetados de forma oposta aos fatores analisados. Quanto menor o tTagmento, maior a abertura do dossel e o grau de perturbação antrópica, maior a proporção de indivíduos menores e menor a proporção de indivíduos de maior tamanho. Indivíduos menores apresentaram maior taxa de mortalidade e maior crescimento, quando comparados a indivíduos maiores. Em escala menor a disponibilidade de luz e a densidade afetaram as relações alométricas (diâmetro x altura) dos indivíduos. Em maior escala, populações com baixa densidade de indivíduos e sujeitas a maior luminosidade variam muito na forma de crescimento. Todas as populações apresentaram declínio populacional. As taxas de crescimento populacional ()v) variaram entre as áreas e no tempo, sendo que para a maioria das populações "A foi menor que 1. As classes de estase contribuíram mais para os valores de "A. As contribuições de transições para mudança de classe de tamanho (crescimento e regressão) apresentaram pouca contribuição à "A As taxas de crescimento populacional ("A) não diferiram entre as populações da floresta contínua e dos fragmentos. As contribuições para 11"A na estase variaram muito entre os anos amostrados. Existiu maior probabilidade nos fragmentos, de indivíduos passarem para uma classe de maior tamanho, e maior probabilidade na floresta contínua de indivíduos regredirem de tamanho. A combinação de diferentes fatores pode alterar a abundância e estrutura de populações de Psychotria sute re lia, e em situações extremas essas alterações podem ser negativas. A grande variação no tempo das taxas de dinâmica podem sugerir estocasticidade demográfica, e o declínio populacional lento das populações na paisagem podem indicar a possibilidade a longo prazo de extinção de algumas populações / Abstract: There is wide variation in the sensibility levei of plant populations to the decrease of their natural habitats. There are also few studies in priority conservation areas. The objective of this study is to test if the discontinuity and quality of the Atlantic Rainforest affect the structure, alometric relations, dynamics, and seed germinability of the populations of a common understory specie, Psychotria suterella (Rubiaceae). Nine populations of the species were sampled in three areas of continuous forests, three connected fragments, and three isolated fragments, in a landscape of fragmented Atlantic Rainforest in São Paulo State, southeastern Brazil. The density of individuais was smaller and the mortality rate of the isolated fragments was higher. All the populations presented a clustered spatial pattern except for a population of one isolated fragment which presented random distribution. The smaller populations presented higher growth, higher mortality rate, and higher recruitment rate. The ditTerences found in the recruitment rates between the populations have no apparently relation with the seeds germination. The germination percentage was not different among the populations. Mortality increased because the intraspecific density also increased. The negative growth increased with the increase of the damage percentage in the individuais. lndividuals of different size class appeared to be affected in the opposite way to the analyzed factors. The proportion of small individuais was higher according to a decrease on the size of the fragment, on increase of the canopy openness, and antropic disturbance. lt worked opposite with larger individuais. Smaller individuais presented a higher mortality rate and higher growth when compared to bigger individuais. ln small scale the density and light conditions affect the alometric relations of individuaIs. ln large scaIe populations with Iow density of individuaIs and higher light conditions may vary a lot in their way of growth. Ali the popuIations presented populational decline. The populations growth rate (À.) varied among areas and in time. For the majority of populations À. was less than 1. The stasis class contributed to the À. values. The contributions of transitions for the change of size class (growth and regression) presented little contribution to À.. The populational growth rate (À.) did not differ among the continuous forest populations and the fTagments. The contribution to /).À. in stasis varied considerably among the sampled years. In the fTagments there was higher probability of individuaIs to get to a class of larger size. In the continuous forest there was higher probability of individuaIs to decrease in size. The combination of different factors may alter the abundance and structure of the Psychotria sllterella populations. In extreme situations these alterations may be negative. The wide variation in time of the dynamics rate may show demographic stocasticity. The slow populational decline of the populations in the landscape may indicate the possibility of extinction of some populations in the long termo / Doutorado / Doutor em Biologia Vegetal

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Orientador: Flavio Antonio Maes dos Santos / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-22T02:00:48Z (GMT). No. of bitstreams: 1 Cavalcanti_AirtondeDeusCysneiros_D.pdf: 6557195 bytes, checksum: beab670108442a3cbaed85443f577345 (MD5) Previous issue date: 2012 / Resumo: O resumo poderá ser visualizado no texto completo da tese digital / Abstract: The abstract is available with the full electronic document / Doutorado / Biologia Vegetal / Doutor em Biologia Vegetal

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Durant les 20 dernières années d'anciens bras latéraux du Rhin ont été restaurés par reconnexion au cours principal. L'objectif de cette thèse est d'évaluer l'efficacité de la restauration et de vérifier si l'écosystème aquatique a retrouvé sa fonctionnalité. Les communautés végétales aquatiques sont utilisées ici comme indicateurs de ces changements. De nombreux facteurs ont été mesurés : les communautés végétales, leurs traits biologiques, les flux et stocks de diaspores, la chimie de l'eau, du sédiment et des plantes, l'hydro-géomorphologie. Cette étude a été menée dans 9 sites restaurés et 3 sites de référence. Trois communautés végétales ont été identifiées : une "eutrophe", une "mésotrophe", et une "rhéophile". La composition de ces communautés est liée aux conditions physiques et trophiques, et aux flux de diaspores. Les reconnexions ont permis aux sites restaurés de retrouver des communautés et une fonctionnalité écologique semblables à celles des sites de référence. / During the last 20 years, side channels of the Rhine have been reconnected to the main course. The objective of this thesis is to assess the efficiency of restoration and the recovery of the ecosystems functionality. The aquatic plant communities were used as indicators of changes. Many factors were monitored: plant communities, their biological characteristics, flux and bank of propagules, the chemistry of water, sediment and plants, hydro-geomorphology. This study was conducted in 9 restored sites and 3 reference sites. Three aquatic plant communities were identified: eutrophic, mesotrophic and rheophilic. The composition of these communities is first linked to physical conditions and second to trophic level, together with flux of propagules. Reconnections allowed the restored sites to exhibit communities and ecological functioning similar to reference sites, in a relatively short time.

Afin de mieux comprendre les effets des changements climatiques sur le pergélisol, il s’avère essentiel d’obtenir une meilleure connaissance des facteurs physiques et biologiques l’influençant. Même si plusieurs études font référence à l’influence de la végétation sur le pergélisol à grande échelle, l’effet de la végétation sur la profondeur du front de dégel du pergélisol à l’échelle de mètres, tel qu’exploré ici, est peu connu. L’étude s’est effectuée dans une forêt boréale tourbeuse dans la zone à pergélisol discontinu au sud des Territoires du Nord-Ouest (N61°18’, O121°18’). Nous avons comparé la profondeur de dégel aux mesures du couvert végétal suivantes : densité arborescente, couvert arbustif, indice de surface foliaire et présence de cryptogames (lichens et bryophytes). Nous avons trouvé qu’une plus grande densité arborescente menait à une moins grande profondeur de dégel tandis que le couvert arbustif (<50cm de hauteur) n’avait aucune influence. De plus, la profondeur de dégel dépendait de l’espèce des cryptogames et des microformes. Cette recherche quantifie l’influence de la végétation par strate sur la dégradation du pergélisol. Ultimement, les résultats pourront être pris en considération dans la mise en place des modèles, afin de valider les paramètres concernant la végétation, la dégradation du pergélisol et le flux du carbone. / In order to better understand the impacts of climate change on permafrost degradation, it is important to understand the influence of abiotic and biotic factors on permafrost dynamics. While studies allude to the effect of broad vegetation groups on permafrost dynamics at landscape-scale, the role vegetation plays in affecting the spatial variability of active-layer development on the scale of metres, as explored here, is largely unknown. The study was carried out in a boreal forest-peatland landscape in the discontinuous permafrost zone in the southern Northwest Territories (N61°18’, W121°18’). We examined the influence of the following vegetation characteristics on the spatial variability of thaw depth: tree density, shrub cover, leaf area index, and cryptogam presence (lichen and bryophyte). We found that greater tree density was associated with shallower thaw depths while shrub cover (<50cm height) had a negligible influence. Furthermore, thaw depth depended on the cryptogam species cover and microform. This research quantifies the impact of vegetation by strata on thaw depth and may ultimately serve to refine vegetation parameters in ecosystem models and land surface schemes as part of climate models.