A pesquisa trata do fenômeno do embuchamento em estacas metálicas tubadas cravadas com ponta aberta. O fenômeno em questão ocorre quando, ao se cravar uma estaca com ponta aberta, o solo que se acumula em seu interior forma um “plug", ou bucha, que altera seu comportamento, tornando-o semelhante ao de uma estaca de ponta fechada sob carregamento estático e, por vezes, até sob carregamento dinâmico. Muitas estacas escavadas, executadas com a presença de lâmina d’água, de rio, de lagoa ou de região portuária, têm como única alternativa de execução, ou alternativa mais viável economicamente, a utilização de camisas metálicas cravadas, de grande diâmetro, para que se atinja a cota de projeto. Se o fenômeno do embuchamento fosse aproveitado, nesse caso específico, a estaca agiria de maneira semelhante a uma cravada de ponta e não a uma escavada, e os coeficientes de segurança utilizados em seu dimensionamento mereceriam uma melhor avaliação. O fenômeno do embuchamento foi apresentado e caracterizado através das referências bibliográficas. Para se avaliar e compreender melhor o fenômeno, utilizou-se modelo matemático baseado nas Leis ou Relações de Cambefort, modificadas por Massad, que, através da curva carga-recalque no topo, permitiram obter o fator de majoração do atrito lateral (μ), que quantifica as cargas residuais presas na ponta em uma estaca. Através do fator μ, obtido em provas de carga encontradas na bibliografia, e da avaliação do formato da curva carga recalque no topo, que pode denunciar, qualitativamente, as fases de mobilização do atrito lateral e da carga de ponta, foi possível comparar o comportamento de estacas tubadas cravadas de ponta aberta, embuchadas e de ponta fechada. A determinação do atrito lateral unitário máximo (fmáx), para os solos atravessados por estas mesmas estacas, e sua posterior comparação com os valores disponíveis na bibliografia de referência, revelou a consistência dos resultados obtidos e que a aplicação dos procedimentos adotados nesta pesquisa requerem que as provas de carga estáticas sejam levadas até a ruptura ou a grandes deformações. / This MSc thesis dealt with the plug phenomenon in open-ended-toes steel pipe piles. This phenomenon occurs when, in the driving process of an open-ended toe pile, the soil that gets into its base alters its behavior, making it similar to one of a close-ended toe under static load and, sometimes, even under dynamic load. Many bored piles, installed with the presence of a water level, on a river, lake or a harbor area, have as the most feasible alternative the use of steel pipes, of large diameter, to achieve the project level. If the plug phenomenon was used, in this specific case, the pile would act in a similar manner of a driven pile and not of a bored pile, and the safety factors used on its calculation would deserve a better evaluation. The plug phenomenon was presented and characterized through the bibliographic references. To evaluate and better comprehend the phenomenon, a mathematical model based on the Cambefort’s Laws, modified by Massad, were used. This model was applied to the load-settlement curve at the top of the pile and allowed to obtain the magnifier factor (μ), that considers residual loads as friction loads. Using the μ factor, obtained in load tests gathered from the literature, and evaluating the shape of the load settlement curve at the pile head, that can denounce, qualitatively, the mobilization phases of the shaft load and the base load, it was possible to establish a relationship between the behavior of driven steel pipe piles, with plugged open-ended toes, and with close-ended toes. The determination of the ultimate unit shaft friction (fu), for the same piles, and its comparison with the existing data on literature, revealed that the values originated from the research were reliable and the procedures adopted in the research required the carrying of the static loads up to the ultimate load or, at least, to a great deformation.

A pesquisa trata do fenômeno do embuchamento em estacas metálicas tubadas cravadas com ponta aberta. O fenômeno em questão ocorre quando, ao se cravar uma estaca com ponta aberta, o solo que se acumula em seu interior forma um “plug”, ou bucha, que altera seu comportamento, tornando-o semelhante ao de uma estaca de ponta fechada sob carregamento estático e, por vezes, até sob carregamento dinâmico. Muitas estacas escavadas, executadas com a presença de lâmina d’água, de rio, de lagoa ou de região portuária, têm como única alternativa de execução, ou alternativa mais viável economicamente, a utilização de camisas metálicas cravadas, de grande diâmetro, para que se atinja a cota de projeto. Se o fenômeno do embuchamento fosse aproveitado, nesse caso específico, a estaca agiria de maneira semelhante a uma cravada de ponta e não a uma escavada, e os coeficientes de segurança utilizados em seu dimensionamento mereceriam uma melhor avaliação. O fenômeno do embuchamento foi apresentado e caracterizado através das referências bibliográficas. Para se avaliar e compreender melhor o fenômeno, utilizou-se modelo matemático baseado nas Leis ou Relações de Cambefort, modificadas por Massad, que, através da curva carga-recalque no topo, permitiram obter o fator de majoração do atrito lateral (μ), que quantifica as cargas residuais presas na ponta em uma estaca. Através do fator μ, obtido em provas de carga encontradas na bibliografia, e da avaliação do formato da curva carga recalque no topo, que pode denunciar, qualitativamente, as fases de mobilização do atrito lateral e da carga de ponta, foi possível comparar o comportamento de estacas tubadas cravadas de ponta aberta, embuchadas e de ponta fechada. A determinação do atrito lateral unitário máximo (fmáx), para os solos atravessados por estas mesmas estacas, e sua posterior comparação com os valores disponíveis na bibliografia de referência, revelou a consistência dos resultados obtidos e que a aplicação dos procedimentos adotados nesta pesquisa requerem que as provas de carga estáticas sejam levadas até a ruptura ou a grandes deformações. / This MSc thesis dealt with the plug phenomenon in open-ended-toes steel pipe piles. This phenomenon occurs when, in the driving process of an open-ended toe pile, the soil that gets into its base alters its behavior, making it similar to one of a close-ended toe under static load and, sometimes, even under dynamic load. Many bored piles, installed with the presence of a water level, on a river, lake or a harbor area, have as the most feasible alternative the use of steel pipes, of large diameter, to achieve the project level. If the plug phenomenon was used, in this specific case, the pile would act in a similar manner of a driven pile and not of a bored pile, and the safety factors used on its calculation would deserve a better evaluation. The plug phenomenon was presented and characterized through the bibliographic references. To evaluate and better comprehend the phenomenon, a mathematical model based on the Cambefort’s Laws, modified by Massad, were used. This model was applied to the load-settlement curve at the top of the pile and allowed to obtain the magnifier factor (μ), that considers residual loads as friction loads. Using the μ factor, obtained in load tests gathered from the literature, and evaluating the shape of the load settlement curve at the pile head, that can denounce, qualitatively, the mobilization phases of the shaft load and the base load, it was possible to establish a relationship between the behavior of driven steel pipe piles, with plugged open-ended toes, and with close-ended toes. The determination of the ultimate unit shaft friction (fu), for the same piles, and its comparison with the existing data on literature, revealed that the values originated from the research were reliable and the procedures adopted in the research required the carrying of the static loads up to the ultimate load or, at least, to a great deformation.

Magister Artium - MA / This thesis investigates the influence of climate change and climatic variability on wetland ecosystems (coastal and inland wetlands) on the Agulhas coastal plain. Firstly, this research examines coastal wetland ecosystem resilience to sea level rise by modelling sea level rise trajectories for the Droё River wetland. The rate of sediment accretion was modelled relative to IPCC sea level rise estimates for multiple RCP scenarios. For each scenario, inundation by neap and spring tide and the 2-, 4- and 8-year recurrence interval water level was modelled over a period of 200 years. When tidal variation is considered, the rate of sediment accretion exceeds rising sea levels associated with climate change, resulting in no major changes in terms of inundation. When sea level rise scenarios were modelled in conjunction with the recurrence interval water levels, flooding of the coastal wetland was much greater than current levels for the 1 in 4 and 1 in 8 year events. The study suggests that for this wetland, variability of flows may be a key factor contributing to wetland resilience. Secondly, the thesis examines the variability of open wetland water surface areas and their relation to rainfall to determine wetland hydrological inputs for the Nuwejaars wetland system and respective wetlands. A remote sensing approach was adopted, Landsat 5 TM and 8 OLI multispectral imagery were used to detect changes of water surfaces for the period 1989 to 2017. Water surfaces were enhanced and extracted using the Modified Normalized Difference Water Index of Xu (2006). The coefficient of variation of wetland water surface area was determined. The variability ranges from low to high for respective wetlands. A correlation analysis of wetland water surfaces and local and catchment rainfall for the preceding 1, 3, 6, 9, 12 and 24 months was undertaken. The preceding month and associated inputs explains the annual variability of surface waters. The study suggests that, the variability of wetland water surface area are related to variations to water inputs and groundwater, as well as variations in water outputs such as evapotranspiration and an outlet channel.

The Maputaland Coastal Plain is situated in north-eastern KwaZulu-Natal Province, South Africa. The Maputaland Coastal Plain and underlying aquifer are two separate but inter-linked entities. This area with high permeable cover sands, low relief and regional geology that slopes towards the Indian Ocean, hosts a variety of important wetlands in South Africa (e.g. 66% of the recorded peatlands). The wetlands overlie and in some cases also connect to the underlying regional water-table. The apparent distribution of wetlands varies in response to periods of water surplus or drought, and over the long-term has been reduced by resource (e.g. agriculture, forestry) and infrastructure (e.g. urbanisation) development. Accurate wetland mapping and delineation in this environment is problematic due to the ephemeral nature of wetlands and extensive land-use change. Furthermore the deep aeolian derived sandy soils often lacks soil wetness indicators in the soil profile. It is postulated that the aquifer is the source of water to rivers, springs, lakes and wetlands (and vice versa). However, the role of groundwater in the sustainability of hydro-ecological systems is unclear. Consequently this research attempted to determine spatial and temporal changes in the distribution of these wetlands, their susceptibility to human development, understand the landscape processes and characterise and classify the different wetland types. An underlying assumption of the hydrogeomorphic wetland classification concept in South Africa is that wetlands belonging to the same hydrogeomorphic unit share common features in terms of environmental drivers and processes. Given the above, the objectives of this thesis relating to the north-eastern corner of the Maputaland Coastal Plain are to: 1) Map the distribution of wetlands and their relation to other land-use; 2) Characterise the landscape processes shaping the dynamics of wetland type and their distribution; 3) Classify wetlands by applying hydrogeomorphic wetland classification system. This study used Landsat TM and ETM imagery acquired for 1992 and 2008 (dry) and Landsat ETM for 2000 (wet) along with ancillary data. Wetland type characteristics were described using terrain unit position in the landscape, SRTM DEM, land surveyor elevation measurements along with long-term rainfall records, in situ water-table levels with soil analysis and geology and vegetation descriptions. A conceptual model was used to account for the available data, and output from a hydrology model was used to support the interpretation of wetland distribution and function. Wetlands in the study area include permanent wetlands (swamp forests and reed/sedge wetlands), but the majority of sedge/moist grassland wetlands are temporary systems. The wetland distribution reflects the rainfall distribution and groundwater discharge in lower lying areas. The weathering of the Kosi Bay Formation is a key factor in wetland formation. Because of an increase in clay content with depth, the pore-space and hydraulic conductivity are reduced which causes water to impede on this layer. The nature of the aquifer and regional geology that slope towards the east along with extreme rainfall events in wet and dry periods are contributing drivers of wetland and open water distribution. In 2008 (a dry year) the smaller wetland extent (7%) could primarily identify “permanent” groundwater-fed wetland systems, whereas for the wet year (2000) with larger wetland extent (18%) both “temporary” and “permanent” wetlands were indicated. Comparison between both dry years (1992 and 2008) indicates an 11% decrease in wetland (sedge/moist grassland) and a 7% increase in grassland distribution over time. Some areas that appear to be grassland in the dry years were actually temporary wetland, based on the larger wetland extent (16%) in 2000. The 2008 Landsat TM dataset classification for the entire Maputaland Coastal Plain gave an overall 80% mapping accuracy. Landscape settings identified on this coastal aquifer dominated by dune formations consist of 3 types: plain (upland and lowland), slope and valley floor. Although the wetland character is related to regional and local hydrogeology as well as climate affecting the temporal and spatial variability of the wetlands this research confirms that the patterns and wetland form and function are predominantly shaped by the hydrogeomorphic setting and not the rainfall distribution. The following wetland types were identified: permanent wetlands such as peat swamp forests, peat reed and sedge fens; temporary wetland systems such as perched depressions, and sedge/moist grasslands. The Hydrogeomorphic wetland classification system was applied using a semi-automated method that was 81% accurate. The following hydrogeomorphic units could be identified: one floodplain, i.e., Siyadla River Floodplain, channelled valley-bottoms, unchannelled valley-bottoms, depressions on modal slope values <1%, seepage wetlands on modal slope values 1-2%. However, evaluation of the hydrogeomorphic classification application results suggests that the “flat” hydrogeomorphic class be revised. It did not fit meaningfully on the upland plain area. This research finding concludes wetland function does depend on landscape setting and wetland function is not truly captured by the hydrogeomorphic type classification. Not all depression on the coastal plain function the same way and three types of depressions occurs and function differently, i.e., perched depression with no link to the regional water-table vs. depressions that are linked with the regional water-table on plain, slope and valley floor landscape settings. Overall, this research study made a useful contribution in characterising and classifying wetland type and distribution for a high priority wetland conservation area in South Africa. Applying similar methods to the broader Maputaland Coastal Plain will particularly benefit from the research findings. The importance of using imagery acquired in wet and dry periods as well as summer and winter for a more comprehensive wetland inventory of the study area, is stressed. To manage the effects of climate variability and development pressure, informed land-use planning and rehabilitation strategies are required based on landscape analysis and interpretation.

Relationships between nutrient heterogeneity, root foraging behavior and short-term competitive interactions were investigated for six species native to southeastern USA. Monoculture, two- and six-species garden plots were established and fertilized to create spatially homogeneous or heterogeneous nutrient conditions. After 3.5 months, root proliferation in rich patches (precision) and aboveground biomass response to heterogeneity were assessed in monocultures, and competitive outcomes (aboveground biomass) were determined from mixed-species plots. In monoculture plots, two species were relatively precise foragers, but no species showed significant aboveground biomass response to nutrient treatment. Correlations between precision and aboveground biomass were weak (-0.40 < r < 0.17). In two-species plots, interspecific competition was influenced by soil heterogeneity in two of six cases tested (P < 0.05), and precision was the behavior most correlated with competitive success. In six-species plots, spatial pattern of nutrients had no influence on aboveground growth or competition. Results suggest that heterogeneity influences competition, but the influence is context-specific and generally small. Precision may be the foraging behavior that most influences interspecific interactions. / Ph. D.

Some alarming trends in commercial forest acreage and pine growing stocks have been developing over the course of four Forest Surveys in eastern Virginia; Forest Survey Unit 1. The importance of the timber resource to the region's economy has brought about a need for research into the long-run timber prospects. Long-run timber output potentials in eastern Virginia are primarily dependent upon two factors: Prospective changes in commercial forest acreage and the intensity with which the forest acreage is managed. An analysis of past trends and a study of the opinions of knowledgeable persons in eastern Virginia lead to the estimate that commercial forest acreage will dec~ease approximately 9 percent by 2020. As for timber management intensity, the study commences with data on cubic-foot yields for the five major forest types, as related to stand age and stocking. From these data, potential yield, per acre and total, is estimated for each class of forest owner. The study finds that in eastern Virginia, nonindustrial private owners are managing their timber much more intensively than generally supposed. In fact, their timber output per acre is on a par with that of public and forest industry owners. If pine timber output is to be increased in the long run, apparently conversion of hardwood stands to pine, not more intensive management of existing stands, will be the means. / Master of Science

I investigated seasonal and inter-site variation in factors influencing diel dissolved oxygen (DO) metabolism at four streams in the Virginia Coastal Plain. Data were collected monthly from January to August 2008 to characterize DO metabolism (diel DO amplitude, production, respiration), incident solar radiation (PAR), dissolved nutrients, fine benthic materials (mass, C:N, Chlα) and hydrology (discharge, water transit time, transient storage). Reach-scale metabolism estimates were determined using the one-station diurnal DO technique and transit time and transient storage were determined by conservative tracer additions. Incident solar radiation was the primary determinant of DO metabolism as streams experiencing higher light levels (Herring and Powell Creeks) exhibited greater diel DO amplitudes, production and respiration. Streams with greater riparian shading (Courthouse and Crump Creeks) exhibited lower DO metabolism despite their higher nutrient concentrations. Higher incident solar radiation was associated with greater benthic algal biomass at some (Herring, Crump, and Courthouse Creeks) but not all (Powell Creek) sites. Diel DO amplitudes were significantly and positively correlated with benthic Chlα and incident solar radiation at less shaded sites. These factors were not significant predictors of DO amplitude, production or respiration at more shaded sites.

On 26 May 2003, intense rainfall from a series of thunderstorms in eastern North Carolina caused flooding that eventually destroyed the concrete dam in Hope Mills, draining Hope Mills Lake, and revealing a formerly submerged and buried structure that was identified as a timber crib dam. Inspection revealed these logs to be old-growth longleaf pines, which are now rare on the coastal plain landscape. Our primary objective was to develop a new multi-century longleaf pine tree-ring chronology by crossdating the tree rings from sections extracted from logs in the crib dam with an anchored tree-ring chronology created from nearby living longleaf pine trees. We also examined the climatic response in the longleaf pine trees to evaluate their potential for reconstructing climate. Using tree-ring measurements obtained from old-growth longleaf pines found at a nearby church, we were able to date the rings on 21 series representing 14 logs from the crib dam, spanning the years 1597 to 1825. Distorted sapwood in many of the logs prevented us from finding absolute cutting dates and lessened the strength of correlation during the period of overlap between the church series and crib dam series. Human disturbances, specifically related to the naval stores industry, likely influenced the growth-ring patterns of the crib dam pine samples, as well. Correlation analyses between the longleaf pine chronology and temperature, precipitation, Palmer Drought Severity Indices, and North Atlantic sea surface temperatures showed a significant response to cool and wet spring months.

O conhecimento do relevo, geologia, cronologia e dos solos nos ambientes costeiros, constitui importante elemento para a interpretação, reconstituição e conservação dos mesmos. Em Bertioga-SP, alguns setores das unidades morfoestratigráficas pleistocênicas e holocênicas, que formam as planícies do litoral paulista, encontram-se preservados na paisagem. A busca pela compreensão da relação entre os solos, o relevo, a natureza e a cronologia dos sedimentos costeiros, acrescida do interesse em estudar os Espodossolos desenvolvidos sobre esses sedimentos direcionaram os objetivos deste trabalho. Para tanto, identificou-se e caracterizou-se os solos e os sedimentos sobre os quais eles se desenvolveram. A fotointerpretação, os trabalhos de campo, as análises químicas, geocronológicas (datações por TL, LOE e 14C) e a granulometria dos solos/sedimentos auxiliaram na identificação, delimitação espacial, bem como o desenvolvimento de teorias sobre a evolução dos solos sobre os depósitos sedimentares. Depósitos continentais, fluviais e marinhos foram identificados. Também foi registrada a influência das formas de relevo e da profundidade do lençol dágua na dinâmica evolutiva e distribuição espacial dos solos em cada unidade geomorfológica. Os Espodossolos, Neossolos, Organossolos, Gleissolos e Cambissolos foram as principais Ordens de solos identificadas. As diferenças topográficas, geomorfológicas e geológicas dos ambientes condicionam a quantidade de água, a fisionomia da vegetação e o conteúdo matéria orgânica nas seis principais unidades geomorfológicas identificadas na planície costeira: (a) depressões fluviolagunares caracterizadas por sedimentos orgânico-pelítico-psamíticos e Organossolos e Gleissolos; (b) terraços marinhos arenosos com predomínio de Espodossolos com ou sem horizontes cimentados (ortstein) e horizontes plácicos; (c) cristas praiais arenosas com Neossolos Quartzarênicos e Espodossolos destituídos de horizontes cimentados (ortstein); (d) rampas de colúvio, psamíticas, com Cambissolos; (e) planície fluvial de granulometria variada com Gleissolos e Neossolos Flúvicos e (f) planícies de maré, psamíticas e pelíticas, onde predominam os Organossolos e Gleissolos. Além dessas unidades, as praias recentes e os setores dominados pelos depósitos continentais colúvio-aluviais indiferenciados também foram abordados como unidades geomorfológicas individuais. A topografia das unidades geomorfológicas de origem marinha, além de indicar a cronologia dos depósitos, influencia no desenvolvimento de diferentes classes de Espodossolos. Os atributos físico-químicos e morfológicos dos Espodossolos podem auxiliar na diferenciação cronológica dos depósitos quaternários mais recentes (holocênicos). A área de ocorrência dos terraços marinhos pleistocênicos é mais extensa do que aquelas registradas nos documentos cartográficos existentes. Nos setores bem drenados dos remanescentes de terraços marinhos pleistocênicos altos, a influência das condições de relevo na pedogênese se reflete na formação dos Neossolos Quartzarênicos (RQ) a partir do desmantelamento dos Espodossolos, enquanto nos terraços marinhos holocênicos os RQ se desenvolvem, podendo evoluir para Espodossolos. / Knowledge of the chronology, relief, geology and soils in sedimentary coastal environments is relevant for their interpretation, reconstitution and conservation. In Bertioga, São Paulo State Brazil, several sections of the Pleistocene and Holocene morphostratigraphic costal plain units are preserved in the landscape. This thesis seeks the perception of the relationships between soils, geomorphology, relief and the chronology of Bertiogas coastal sand deposits as well as to study Podzols developed on them. Soils and the different sedimentary environments where these soils develop were thus identified and characterized. Photointerpretation, field work, chemical, physical and chronological (luminescence and radiocarbon dating) analysis supported the identification, spatial delimitation as well as the development of genesis theories of soils over continental, fluvial and marine deposits. Previous data additionally allowed the evaluation of the influence of relief forms and water table depth on the evolutionary dynamics of soils and on their spatial distribution pattern. The main identified orders of soils included Podzols, Arenosols, Fluvisols, Histosols, Gleysols and Cambisols. The topographic, geomorphologic and geologic differences of the environments had conditioned the amount of water, the vegetation features and the organic matter content of the following geomorphologic units: (a) lagoonal terrace depressions, characterized by organo-pelitic-psammitic sediments under Histosols and Gleysols; (b) marine terraces formed by fine to very fine sand under Podzols with and without hardpans (ortstein); (c) fine sandy beach ridges with a dominance of Arenosols and, on a secondary level, Podzols without hardpans (ortstein) and placic horizons; (d) psammitic colluvial slope deposits with Cambisols; (e) fluvial plains with varied texture and with Gleysols and Fluvisols and (f) psammitic and pelitic tidal flats, where Histosols and Gleysols predominate. Besides these units, modern beaches and sections dominated by non-differentiated colluvial-alluvial continental deposits were also analyzed as individual geomorphological units. Topography of geomorphological units from marine origin indicates the chronological sequence of deposits, in addition to influencing the development of different of Podzols, the physical, chemical and morphological properties of which allowed the chronological differentiation of modern Quaternary deposits (Holocene). The mapped area of the Pleistocene marine terraces occurrence was found to be larger than the one indicated on cartographic documents published up to the moment. In the well-drained sections of remnant soils from high Pleistocene marine terraces, the influence of the relief forms on pedogenesis is shown through the formation of Arenosols originated from the destruction of spodic horizons, whereas Arenosols in Holocene marine terrace tends to evolve into Podzols.

A nucleação é uma técnica de restauração florestal na qual se espera que o plantio agregado de mudas aumente o recrutamento e o estabelecimento de espécies, uma vez que o crescimento de algumas plantas pode fornecer melhores condições ambientais para as plantas vizinhas. Porém, o plantio agregado também pode intensificar a competição por nutrientes entre as plantas. Espera-se que o efeito facilitador do núcleo seja maior para espécies não pioneiras, que são mais sensíveis a altas irradiâncias e melhores competidoras por nutrientes. Para espécies pioneiras, tolerantes a altas irradiâncias e piores competidoras, os núcleos devem ser desfavoráveis. A adição de nutrientes pode minimizar a competição e tornar os núcleos mais favoráveis, principalmente às espécies pioneiras. Com o objetivo de avaliar respostas das mudas à nucleação e à adição de nutrientes, foram avaliados a eficiência fotossintética máxima (Fv/Fm) e o conteúdo de pigmentos fotossintéticos. Temperaturas foliares e do solo foram medidas para avaliar o potencial do núcleo em minimizar microclimas extremos. As mudas foram plantadas em parcelas, cada uma com uma combinação de tipo de plantio, em núcleo ou em linha, e tipo de adubo aplicado, com adubo químico (NPK), com terra vegetal ou sem adubação. Os núcleos foram compostos de 13 mudas de espécies diferentes, sendo 5 pioneiras e 8 não pioneiras. As mudas foram separadas entre si por distâncias de aproximadamente 30 cm. Nas linhas as mudas foram plantadas isoladas entre si por 2 m. Mudas plantadas no sistema de nucleação apresentaram melhores condições, com maior Fv/Fm e conteúdo de clorofilas a, b e total (a+b), indicando efeitos de facilitação do núcleo. Menores temperaturas foliares e do solo foram encontradas em núcleos. Tanto plantas de espécies pioneiras quanto não pioneiras apresentaram sinais de fotoinibição, com valores de Fv/Fm abaixo do considerado como livre de estresse, quando plantadas tanto em linhas quanto em núcleos. Os sinais de fotoinibição foram maiores para o grupo de não pioneiras, com menores valores Fv/Fm. Não pioneiras apresentaram menor razão de clorofila a/b, evidenciando seu investimento em absorver maior quantidade de luz. Entretanto, o efeito diferenciado dos núcleos para espécies pioneiras e não pioneiras não foi conclusivo, assim como os efeitos da adição de nutrientes. O presente estudo fornece evidências para o efeito de facilitação em núcleos, agregando mais uma informação aos efeitos benéficos da nucleação, fornecendo subsídios para a recomendação da utilização dessa técnica em restauração. Não foram encontrados indícios que o plantio em núcleos seja prejudicial para pioneiras ou não pioneiras, justificando, dessa forma, o plantio de núcleos mistos / Nucleation of seedlings is a technique for forest restoration in which is expected that the aggregated planting of seedlings increases the recruitment and establishment of species. This would occur because the growth of some species can provide better environmental conditions to neighboring plants. However, the aggregated planting can also intensify the competition for nutrients between plants. It is expected that the facilitating effects are greater for the non-pioneers species that are more sensitive to high light intensities and better competitors for nutrients. For pioneers that are tolerant to high irradiance and worst competitors, the nuclei must be unfavorable. The addition of nutrients can minimize the competition and then turn the nuclei more favorable, especially to the pioneer species. In order to evaluate the responses of seedlings to the nucleation and the addition of nutrients were measured the maximum photosynthetic efficiency (Fv/Fm) and the content of photosynthetic pigments. Foliar and soil temperatures were measured to assess the potential of nucleation to minimize extreme microclimates. The seedlings were planted in plots, each with a combination of type of planting in nucleus or line, and type of fertilizer applied, chemical fertilizer (NPK), topsoil or without fertilizer. The nuclei were composed of 13 seedlings of different species, 5 pioneers and 8 non-pioneer pioneers. The seedlings were separated from each other by distances of approximately 30 cm. Seedlings planted in lines were isolated from each other by 2 m. Seedlings planted in the nucleation system showed better conditions with greater Fv/Fm and chlorophyll a, b and total contents, indicating the facilitation effects of nucleation. Foliar and soil temperatures were lower in nuclei. Both pioneers and non-pioneers showed signals of photoinhibition, with values of Fv/Fm below of that considered as stress-free when were planted in both, lines or nuclei. Photoinhibition signals were higher for the group of non-pioneer with lower Fv/Fm values. Non-pioneers had lower ratio of chlorophyll a/b, evidencing their investment to absorb more light. However, the different effects of nuclei for pioneers and non-pioneer species were not conclusive, as well as the effects of the addition of nutrients. The present study provides evidence for the effect of facilitation in nuclei, adding more information to the beneficial effects of nucleation, providing aid for the recommendation of the use of this technique in projects of ecological restoration. No evidence that planting in nuclei is harmful to pioneer or non-pioneer were found, thus justifying the planting of mixed nuclei