D.Phil. / What underlies species distribution and species coexistence has long been of key interest in community ecology. Several methods and theories have been used to address this question. However, it still remains a controversial debate. The recent development of plant DNA barcodes with possibility of merging phylogeny with ecology brings high expectation in uncovering the processes underlying community assemblages. Previous works that used molecular approach in community ecology focused mainly on rainforests. Using a phylogenetic approach, this study brings novel understandings about savanna ecology, especially regarding how megaherbivores impact plant community composition. The Kruger National Park (KNP) is one of the world’s largest reserves, but less studied from a phylogenetic perspective. A DNA database of 445 DNA sequences (plant DNA barcodes, rbcLa + matK) was generated for the woody plants of the KNP. This database proves reliable in reconstructing the phylogeny of Angiosperms of the park. Based on this phylogeny, the present study characterised plant community composition, and investigated how megaherbivores influence this composition. Results indicate that plant communities in the KNP are not neutral, i.e. they are more clustered than expected under various null models. This suggests that ecological forces, most likely habitat filtering may be playing key role in dictating community structure in the KNP. The KNP is well-known for its richness in megaherbivores. The contribution of these animals to the current shape of plant community structures was therefore further investigated. Where megaherbivores have been excluded, plant diversity decreases, but shifts in plant community structure are contingent upon the initial community composition, suggesting that herbivory might be important filter that drives the clustering pattern observed.

A restauração ecológica tem como principal objetivo o restabelecimento de um ambiente florestal com a retomada das funções ecológicas entre as comunidades que o compõem e o meio abiótico, possibilitando que essa floresta se mantenha autosustentável no tempo. Entretanto, muitos desses fragmentos restaurados estão se desestruturando devido a erros cometidos na implantação inicial dos projetos e também devido à pequena chegada de propágulos vindos de fragmentos do entorno que, em geral, estão cada vez mais degradados. O que se observa são florestas com pouca regeneração no sub-bosque impedindo que o processo de substituição de espécies do dossel ocorra naturalmente, além da invasão por espécies arbustivo-arbóreas e gramíneas exóticas, baixa diversidade, dominância de poucas espécies plantadas, baixa oferta de recursos para a fauna etc. Nesse contexto torna-se necessário o monitoramento e avaliação do estado atual dessas áreas assim como o emprego de técnicas de restauração ecológica que visem aumentar a diversidade florística e de formas de vida presentes na área, além da variabilidade genética, que por sua vez irão contribuir com as interações ecológicas e perpetuação da comunidade. O objetivo desse estudo foi caracterizar a comunidade arbustivo-arbórea presente através de um estudo florístico e fitossociológico e analisar o potencial da transferência de bancos de sementes superficiais para enriquecer uma área restaurada de Floresta Estacional Semidecidual há 13 anos no entorno da represa São Luiz em Santa Bárbara DOeste, SP. O bancos de sementes superficiais foram coletados de uma área restaurada há 50 anos e de uma floresta de Pinus sp abandonada de modo a avaliar se estes locais podem se constituir importantes fontes de sementes para o enriquecimento, tanto de áreas que obtiveram insucesso na restauração como em áreas naturais secundárias. O estudo florístico e fitossociológico demonstrou que, assim como a maioria dos fragmentos restaurados no Estado de São Paulo, sua sustentabilidade pode estar comprometida por não desencadear o processo de sucessão ecológica. O banco de sementes da floresta da Pinus apresentou um maior número de espécies e indivíduos regenerantes, apesar da maioria deles ser de espécies herbáceas e arbustivas. Contudo o pouco número de espécies arbóreas que ocorreu apresentou uma densidade absoluta elevada quando considerada em um hectare. Além disso, foram registradas formas de vida interessantes do ponto de vista ecológico, como Piper sp e uma espécie de pteridófita. Desta forma, esses resultados demonstram o potencial da técnica de enriquecimento através da transferência de bancos de sementes superficiais, sendo necessários estudos mais bem detalhados que visem uma maior diversidade de espécies introduzidas e a mensuração dos custos e rendimentos operacionais da técnica. / The main objective of ecological restoration is the reestablishment of a forest environment in a way to bring back the ecological functions between communities and the abiotic components, making it possible for the forest to be self-sustainable through time. However, many of these restored fragments are unsuccessful because of mistakes made in the initial stages of restoration projects and also due to small inputs of propagules coming from neighboring fragments which, in general, are in a continuous degradation process. Forests showing low regeneration potential in the understory are commonly observed, which hinders the natural process of canopy species substitution and favors the invasion by shrub-tree species, exotic grasses, low diversity, dominance of a few planted species, low offer of resources for the fauna etc. In this frame, it is necessary to monitor and to evaluate the current state of such areas as well as the use of restoration techniques to increase floristic and life forms diversity besides genetic variability which, in turn, will augment ecological interactions and community selfperpetuation. This study aimed to characterize the shrub-tree community by a floristic and phytosociological study, and to analyze the potential of superficial seed banks transfer to enrich a 13-year old restored Seasonal Semidecidual Forest fragment located around the São Luiz water reservoir in Santa Bárbara DOeste, SP, Brazil. Superficial seed banks were collected from a 50-year old restored forest and from an abandoned Pinus sp. plantation to test if these areas can serve as sources of seeds for the enrichment of both unsuccessful restored areas and natural secondary forests. The floristic and phytosociological studies showed that, as for the majority of the restored forest fragments in São Paulo State, the maintenance of the studied fragment may be compromised for not having triggered ecological succession yet. The abandoned Pine plantation seed bank showed a higher number of species and regenerating individuals, despite the fact that most of them were herbs and shrubs. However, the small number of tree species found had high absolute density when extrapolating to one hectare. Moreover, we found interesting life forms, from the ecological perspective, such as Piper sp. and a fern species. This way, our results demonstrate the potential the technique of enrichment by superficial seed bank transfer has. More detailed studies are necessary aiming higher diversity of introduced species and the measures of costs and operational yield of this technique.

O padrão espacial das árvores em uma floresta é influenciado por variáveis abióticas e bióticas. Entre as principais variáveis abióticas estão o relevo, a disponibilidade de luz, nutrientes e água, e a caracterização do solo. Entre as principais variáveis bióticas estão os processos dependentes da densidade, tais como a competição intraespecífica e interespecífica, a herbivoria, a ocorrência de doenças, a fenologia e dispersão de sementes. Desse modo, investigar o padrão espacial das árvores, segundo suas classes de tamanho, e segundo suas espécies mais abundantes, pode fornecer evidências sobre a estrutura da comunidade vegetal. A descrição do padrão espacial das árvores e das espécies mais abundantes em diferentes formações florestais foi realizada usando ferramentas estatésticas mais apropriadas para investigar mapas das árvores. A Função K de Ripley tem como principais vantagens a possibilidade de detectar o padrão espacial em diversas escalas de distâncias simultaneamente, e avaliar a dependência espacial entre grupos de árvores. Os padrões observados foram comparados com os modelos de Completa Aleatoriedade Espacial, para a função univariada, e de Completa Independência Espacial, para a função bivariada. Diferentes formações florestais, típicas da região sudeste do Brasil, foram comparadas neste estudo: Floresta Ombrófila Densa Submontana, Savana Florestada (Cerradão), Floresta Estacional Semidecidual e Formação Pioneira com Influência Marinha (Restinga). Esta dissertação de mestrado integra o Projeto "Diversidade, dinâmica e conservação em florestas do Estado de São Paulo: 40 ha de parcelas permanentes", do Programa Biota da FAPESP. Neste projeto, uma parcela de 10,24 ha foi montada em cada formação florestal, e todas as árvores com circunferência na altura do peito a partir de 15 cm foram medidas, mapeadas e identificadas. Os resultados obtidos neste estudo ressaltam o caráter agregado em florestas tropicais, uma vez que o padrão agregado foi observado em todas as florestas estudadas. As árvores do Cerradão e da Restinga apresentaram padrões muito próximos, com uma agregação definida até uma certa escala de distâncias. Para a Floresta Ombrófila, o padrão agregado foi significativo em toda a escala de distâncias. Na Floresta Estacional, tendência à aleatoriedade foi observada, embora uma agregação significativa tenha sido notada para curtas distâncias. A análise do padrão espacial segundo classes de tamanho mostrou que as primeiras classes possuem, em geral, padrões agregados significativos, enquanto para as classes seguintes o padrão aleatório foi predominante. Em linhas gerais, o padrão espacial das espécies acompanhou o padrão geral de cada formação florestal. O padrão das espécies dominantes é sempre muito semelhante ao padrão espacial da floresta como um todo. Como era esperado, as espécies dominantes desempenham importante papel na ocupação do espaço horizontal em tais florestas, contribuindo de modo decisivo para a caracterização do padrão espacial da comunidade. Espécies que ocorreram em diferentes florestas apresentaram pequenas diferenças no seu padrão espacial, ressaltando-se assim a importância da sua autoecologia e dos processos ecológicos intrínsecos a cada comunidade. / Tree spatial patterns are influenced by abiotic and biotic environment. Among the main abiotic factors are topography, light, nutrients, soil and water availability. Among biotic factors are density-dependent processes, as intraespecific and interespecific competition, herbivory, pathogens, phenology and seed dispersion. Investigation of tree spatial patterns, patterns in size classes, and dominant species patterns can show evidences about the structure of plant communities. Description of trees spatial pattern was made using the most appropriate statistical tools for mapped data. Ripley’s K Function has as its main attributes the power to detect the spatial patterns in different distance scales simultaneously, and to investigate spatial independence among groups of trees. Observed patterns were compared to Complete Spatial Randomness model, in univariate function, and to Complete Spatial Independence model, in bivariate function. Different forests, typical from Southeastern Brazil, were compared in this study: Forest Savanna (Cerrad˜ao), Dense Rain Forest, Seasonal Semideciduous Forest and Restinga. This mastership thesis is part of Project "Diversity, dynamics and conservation in forests in the State of São Paulo: 40 ha of permanent plots", from FAPESP Biota Program. In this project, one permanent plot of 10.24 ha was located in each forest stand, and all its trees with circunference at breast height equals 15 cm or higher were measured, mapped and identified. The results obtained in this study shows the aggregated pattern as the most common pattern in tropical forests. The trees spatial pattern in Cerradão and Restinga were very similar, aggregation was observed in the same distance scales. For the Dense Rain Forest, the spatial pattern was significant for all the distance scales. In Semidecidous Forest, a tendency towards randomness was observed, but a significant aggregation appeared for short distances. The spatial analysis for size classes showed that the newer classes have aggregated patterns, while the following classes have random ones. The dominant species spatial patterns were close to the general patterns of its community. As expected, dominant species play important rules in characterizing the horizontal pattern of their forests. Common species between different forests showed small differences in its spatial pattern, indicating the importance of its autoecology and the intrinsic ecological processes of each community.

Métodos de amostragem no levantamento da comunidade arbórea em floresta estacional semidecidual foram comparados. Primeiro foi testado o método de Bitterlich a fim de selecionar o fator de área basal mais adequado para o estudo da comunidade arbórea. O critério de inclusão adotado foi todas as árvores com DAP > 10 cm. Os fatores de área basal de 2, 3 e 4 m 2 ha -1 amostraram 596, 408 e 297 indivíduos e 59, 57 e 50 espécies, respectivamente. As estimativas de área basal, DAP médio, diversidade e equabilidade não apresentaram diferenças significativas. O fator de área basal igual a 3 foi selecionado porque mostrou melhor resultado em relação ao tempo gasto e facilidade de campo. Em uma segunda análise, os métodos de parcelas de área fixa (100 parcelas contíguas), pontos quadrantes e pontos de Bitterlich foram comparados para o levantamento da comunidade arbórea. O critério de inclusão adotado foi todas as árvores > 10cm. As 100 parcelas contíguas de 10x10m amostraram 59 espécies. Os 177 pontos de quadrantes amostraram 69 espécies e os 45 pontos de Bitterlich (fator de área basal = 3 m 2 ha -1 ) amostraram 57 espécies. Ocotea indecora foi favorecida pelo método de Bitterlich. O método de Bitterlich apresentou dificuldades no trabalho de campo devido a falta de visibilidade em algum pontos. Entretanto esse método apresentou melhor resultado na amostragem de espécies quando o esforço amostral é analisado por unidades amostrais. O método de quadrantes foi melhor na análise do esforço amostral por tempo. Na terceira análise o efeito de desvios da completa aleatoriedade espacial sobre a estimativa de densidade produzida pelo método de quadrantes foi analisada através de simulação de Monte Carlo. Foram geradas florestas hipotéticas com padrão espacial regular e agrupado com diferentes densidades. O efeito do tamanho da amostra também foi analisado, porém não mostrou efeito significativo na redução do viés. Os valores de viés relativo da estimativa da densidade variaram desde +70,3% (florestas regulares) até -75,7% (florestas fortemente agrupadas). A densidade de árvores não causou efeito na estimativa do viés, com exceção para as florestas completamente aleatórias e regulares em lattice aleatorizado. O método de quadrantes superestima a densidade arbórea para as florestas com padrão regular e subestima a densidade para as florestas com padrão espacial agrupado. É importante saber a priori o padrão espacial da floresta a fim de se aplicar o método de quadrantes e saber interpretar os seus resultados. / Sampling methods for surveying in tree species community in a semideciduos forest were compared. First was applied the angle count sampling method and select the best basal area factor to study the tree community. The criterion of inclusion adopted was all trees with DBH > 10cm. The basal factors 2, 3 and 4 m 2 ha -1 sampled 596, 408 and 297 individuals and 59, 57 and 50 species. The estimates of basal area, mean DBH, density, diversity and equability are not significantly differents among basal area factors. The basal area factor 3 was selected because showed better performance in terms of time spent and field operation. In a second analysis three sampling methods were compared for survey tree species community: fixed area plot (100 contiguos plots), point centered quarter method and Bitterlich method. The criterion of inclusion adopted was all trees with DBH > 10cm. The 100 contiguous plots of 10x10m showed 59 species. The 177 centered quarter method sampled 69 species and the 45 angle count points (basal area factor = 3 m 2 ha -1 ) showed 57 species. Ocotea indecora was favored by the Bitterlich method. Bitterlich method presented difficulty in field operation due to the lack of visibility in some sample points. However it better presented performance in the sampling of species in the amostral effort for plots. The centered quarter method was better in the amostral effort for time. In a third analysis the effect of deviation from the complete spatial randomness on point centered quarter method estimate of forest density was analysed through Monte Carlo simulation of hypothetical forests with regular and clustered spatial patterns and with diferent densities. The influence of sample size was also analysed, but showed no marked effect on estimation biases. The relative bias on the tree density estimation varied from +70.3% (regular lattice spatial pattern) to -75.7% (strongly clustered spatial pattern). Tree density did not affected estimation bias, except for completely spatial pattern and randomized regular lattice pattern. Point-centered quarter method overestimate (positive bias) tree density for regular patterns and underestimate (negative bias) for clustered patterns. Knowledge of tree spatial pattern in a forest is necessary for correct implementation and results interpretation in this method.

En marge arrière d’aire de répartition, les espèces persistent ou disparaissent en réponse aux changements climatiques et autres facteurs globaux. Les refuges climatiques ont joué un rôle majeur dans la persistance de la biodiversité au cours des périodes de transitions climatiques majeures et une compréhension mécaniste claire de leur fonctionnement est primordiale pour la conservation des populations de marge arrière. En limite géographique sud-ouest de son aire de distribution, des fragments de hêtre (Fagus sylvatica) persistent dans des micro-refuges en raison de facteurs locaux. Connue pour sa biodiversité remarquable, la vallée du Ciron offre un laboratoire naturel idéal pour l'étude des refuges climatiques et la prédiction de leur évolution dans un climat régional de plus en plus chaud et sec. Cette thèse interdisciplinaire est centrée sur l’étude des populations de hêtres et des communautés associées par des approches in situ et ex situ combinant écologie des communautés et physique de l’environnement. Nos résultats mettent en évidence une forte originalité floristique des communautés du sous-bois des populations à hêtre de marge chaude, ainsi que l’existence de variations microclimatiques à fine échelle, fonction notamment de la topographie, de la présence de la rivière et de la localisation dans le paysage. Nous montrons que la régénération du hêtre dépend du microclimat et qu’elle est modulée par des interactions allélopathiques. De plus, notre étude met en avant le rôle facilitateur de la canopée forestière ainsi que l’importance du rayonnement solaire, au moins dans des conditions où ce dernier impacte peu la disponibilité en eau. L’ensemble des résultats suggèrent la persistance probable du hêtre dans la vallée du Ciron ainsi qu’une potentialité de présence plus importante dans le Bassin aquitain. / In the margin of their distribution range, species can persist or disappear in response to climate change and global factors. Climate refugia have played a major part in the persistence of biodiversity during periods of fundamental climatic transitions, and a clear mechanistic understanding of their functioning is essential for the conservation of marginal populations. In the southwestern geographical limit, fragments of beech populations (Fagus sylvatica) persist in micro-refugia due to the importance of local factors. Known for its remarkable biodiversity, the Ciron valley provides an ideal natural laboratory for studying climate refugia and predicting their evolution in an increasingly hot and dry regional climate. This interdisciplinary thesis involves the study of beech populations and associated communities through in-situ and ex-situ approaches combining community ecology and environmental physics. Our results underline the strong floristic originality of the undergrowth communities of warm-margin beech populations, and reveal the existence of fine-scale microclimatic variations caused, in particular, by the local topography, the presence of the river, and location in the landscape. We show that beech regeneration depends on microclimate and that it is modulated by allelopathic interactions. Moreover, our research highlights the facilitating role of the forest canopy and the importance of solar radiation, in conditions where it has low impact on water availability. The overall results suggest the likely persistence of beech in the Ciron Valley and a greater potential presence of beech in the Aquitanian Basin.

The University of South Florida Ecological Research Area (USF Eco Area), located in west central Hillsborough County, is an approximately 306 hectare (756 acre) natural area on the Hillsborough River composed of twelve plant communities. While surrounded on three sides by urbanization, the USF Eco Area makes up the western most section of an extended natural corridor that runs approximately 88 kilometers (55 miles) east and north along the Hillsborough River. An inventory of the vascular flora and the associated ecological communities was developed to better assess the USF Eco Area for educational and research purposes as well as enhance informed decisions when evaluating its status for conservation and management purposes. The study, conducted from June 2001 through August 2005, documented 404 vascular plant taxa in 251 genera and 102 families. Three hundred and seventy-eight taxa (94%) are native to Florida of which 13 are endemic; nine are listed as endangered, threatened, or commercially exploited; four are first time recorded occurrences for Hillsborough County; and ten taxa are listed as Florida Exotic Pest Plant Council’s Category I or II invasive species. Eleven natural plant communities and one ruderal/developed plant community were documented, mapped and characterized by their unique vegetative, topographic, soil, and hydrological components based on qualitative field observations. The blackwater stream, floodplain swamp, floodplain forest, floodplain marsh, hydric hammock, seepage slope, and wet flatwoods are wetland plant communities that cover 65% of the USF Eco Area. Upland plant communities, covering the remaining 35%, are mesic flatwoods, scrubby flatwoods, sandhill, xeric hammock, and ruderal/developed.

Title supplied by cataloguer. / Lacks title page and contents. / Includes bibliographical references. / 17 items : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / A collection of 17 of the author's publications including a manuscript copies of chapters 4-8 of The vegetation of South Australia (published Adelaide : Govt. Printer, 1937); and,Time factors in photosynthesis; and copies of papers reprinted from various journals; all submitted as the author's Doctor of Science thesis / Thesis (D.Sc.)--University of Adelaide, 1934

Thesis (M.S.)--Oregon State University, 1978. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

A severe wildfire burned 454 hectares of a second-growth Douglas-fir forest in 1977 on a north-facing slope in Pattee Canyon, near Missoula, Montana. The slope was aerially seeded with a grass mixture, from which Dactylis glomerata established best. Community structure, conifer regeneration, and the impact of the seeded grass on the plant community were evaluated with two data sets. One set tracked postfire vegetation development from 1979 to 1987 on permanent transects established on upland sites in areas of varying fire severity. The second data set was collected in 1989 on upland sites nearest to the bum edge where conifer regeneration was expected to be greatest. Most stands converged to a similar ordination space by 1987, showing that several key species which established in the initial postfire year determined community structure. These species were largely on-site survivors (including Calamagrostis rubescens, Physocarpus malvaceus, and Spiraea betulifolia) and the seeded grass, D. glomerata. The spread of this species by 1987 to stands that apparently escaped seeding in 1977 suggested that this species may persist at this site. Patterns of species abundance and distribution in 1989 were primarily controlled by factors summarized by a topographic-moisture index and by pre-burn disturbance history. Three general site types were described by an ordination. Areas that appeared as open woodlands in 1937 occurred on ridges and had more xerophytic vegetation in 1989, including native grasses. Conifer regeneration in this region was limited primarily to Pseudotsuga menziesii (Douglas-fir). Areas that appeared as an even, young forest in 1937 were on open slopes and were associated with Pinus contorta (lodgepole pine), Larix occidentalis (western larch), Vaccinum globulare, and Amelanchier alnifolia. Areas that appeared as an older, uneven-aged forest in 1937 were on open slopes near the upper burn edge and were characterized by Douglas-fir and Spiraea betulifolia in 1989. D. glomerata was more successful on the drier ridges and was negatively associated with Calamagrostis rubescens. Competition with C. rubescens, rather than differences in environmental tolerances, most likely restricted D. glomerata to the more xeric sites. An adverse effect of D. glomerata on conifer regeneration was most likely for western larch on xeric sites. Site factors and historical factors were most important in determining patterns of conifer regeneration. Regeneration was moderate on mesic slopes and sparse on xeric ridges. The extreme density of lodgepole pine regeneration (13,000 stems/hectare) in one mesic area reflected the importance of serotiny for post-fire regeneration of this species. Douglas-fir regeneration ranged from 370 stems/ha in a mesic area where no mature survivors were noted to 4045 stems/ha on a mesic slope near survivors. On mesic slopes near survivors, western larch regeneration was 857 stems/ha and was minimal elsewhere. A regression model confirmed the importance of site factors, site history, and availability of seed source for Douglas-fir and lodgepole pine. The model for western larch was only able to explain 14% of regeneration pattern, suggesting that microsite variation as well as other variables would be needed to predict regeneration for this species. / Graduation date: 1992

Thesis (M.S.) in Ecology and Environmental Science--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 78-87).