Woody plant invasion of grasslands is prevalent worldwide, but the biogeochemical consequences of this vegetation shift remain largely unquantified. In the Rio Grande Plains, TX, grasslands and savannas dominated by C4 grasses have undergone succession over the past century to subtropical thorn woodlands dominated by C3 trees/shrubs. To elucidate mechanisms of soil organic carbon (SOC) and soil total N (STN) storage and dynamics in this ecosystem, I measured the mass and isotopic composition (δ13C, δ15N) of C and N in whole-soil and soil size/density fractions in chronosequences consisting of remnant grasslands (Time 0) and woody plant stands ranging in age from 10-130 years. Rates of SOC and STN storage averaged 10-30 g C m-2yr-1 and 1-3 g N m-2yr-1, respectively. These accumulation rates increased soil C and N pools 80-200% following woody encroachment. Soil microbial biomass (SMB-C) also increased after woody invasion. Decreasing Cmic/C org and higher qCO2 in woodlands relative to grasslands suggests that woody litter is of poorer quality than grassland litter. Greater SOC and STN following woody invasion may also be due to increased protection of organic matter by stable soil structure. Soil aggregation increased following woody encroachment; however, most of the C and N accumulated in free particulate organic matter (POM) fractions not protected within aggregates. Mean residence times (MRTs) of soil fractions were calculated based on changes in their δ13C with time after woody encroachment. Free POM had the shortest average MRTs (30 years) and silt+clay the longest (360 years). Fine POM had MRTs of about 60 years, reflecting protection by location within aggregates. δ15N values of soil fractions were positively correlated with their MRTs, suggesting that higher δ15N values reflect an increased degree of humification. Increases in SOC and STN are probably being sustained by greater inputs, slower turnover of POM (some biochemical recalcitrance), and protection of organic matter in aggregates and association with silt and clay. Grassland-to-woodland conversion during the past century has been geographically extensive in grassland ecosystems worldwide, suggesting that changes in soil C and N dynamics and storage documented here could have significance for global C and N cycles.

Anthropogenic activities are responsible for increases in atmospheric CO₂ and climate change. These increases are partly counterbalanced by natural processes, such as carbon uptake in land surfaces. These processes are themselves subject to climate change, creating a coupled carbon-climate system. I investigated the carbon sink that woody encroachment represents, using a Central Texas savanna as study site, and studied how climatic factors influence this carbon sink. Woody plant encroachment, a worldwide structural change in grassland and savanna ecosystems, alters many ecosystem properties, but the net effect on the carbon balance is uncertain. Woody encroachment represents one of the key uncertainties in the US carbon balance, and demands a more detailed understanding. To come to a process-based understanding of the encroachment effect on carbon dynamics, I analyzed patterns of carbon exchange using eddy-covariance technology. I expected the imbalance between carbon uptake and release processes associated with the encroaching trees specifically, to be responsible for the carbon sink. I also expected that the sink would vary in time, due to strong links between carbon fluxes and soil water in this semi-arid ecosystem. I further studied the ecophysiology of the dominant species, as well as soil respiration processes under different vegetation types, and scaled these findings in space and time. I found that the ecosystem was a significant carbon sink of 405 g C m⁻² yr⁻¹. The encroaching trees increased photosynthesis by 180% and decreased soil respiration by 14%, compared to the grassland, resulting in a strong carbon sink due to the encroachment process. The encroaching process also altered carbon dynamics in relation to climatic drivers. The evergreen species Ashe juniper effectively lengthened the growing season and widened the temperature range over which the ecosystem acts as a carbon sink. The drought resistance of the encroaching trees reduced the sensitivity of this savanna to drought. I conclude that encroachment in Central Texas savannas increased the carbon sink strength by increasing the carbon inputs into the ecosystem. Woody encroachment also reduced the sensitivity to climatic drivers. These two effects constitute a direct effect, as well as a negative feedback to the coupled carbon-climate system. / text

Savannas are globally important ecosystems characterized by the coexistence of trees and grasses. Woody plants, which are slow-growing dominant life forms, influence the physiognomic structure and function of savanna ecosystems. Their density and distribution provides sustenance to a vast and unique savanna biodiversity, by forming a major source of food material to large mammalian herbivores, sheltering them and through their facilitation of diverse plant species. Savanna tree existence is strongly affected by factors that determine their sapling recruitment. We defined „sapling‟ as a young tree, in the first season of its growth, which does not depend on cotyledonary reserves (=seedling stage) and relies on external resources to grow further. Sapling recruitment may strictly be defined as the progression of a young plant from seedling to sapling stage. However, we believe that savanna tree saplings, present within the grass layer in the initial years of their growth, are equally vulnerable to environmental stresses. This study examines the factors affecting tree sapling establishment in a humid savanna (1250 mm mean annual precipitation). Additionally, the effects of fire were tested in a greenhouse experiment. Dominant species from humid savannas (> 1000 mm MAP), Acacia karroo, Acacia sieberiana, Schotia brachypetala and Strychnos spinosa, and mesic savannas (approx. 750 mm MAP), Acacia nigrescens, Acacia tortilis, Colophospermum mopane and Combretum apiculatum, were studied. In this thesis I examined the effects of resource availability (water, nutrients and light), disturbances (fire and herbivory) and competition (grass) on the sapling ecology of these species. Sapling recruitment and growth were assessed in terms of survival and aboveground growth responses, i.e. total biomass, stem growth rates (used as proxy measures for assessing persistence) and leaf biomass proportion (important for producing root reserves necessary to resprout). I studied the effects of fire and a nutrient gradient on survival and growth of four Acacia species in the presence of grass competition, in a controlled greenhouse experiment. Generally, Acacias invest in defenses after herbivory. I also determined their physical and chemical defense investments in this experiment. Sapling survival was not influenced by nutrients but highly varied among the species due to fire, indicating that fires may have a differential effect on species composition at a landscape scale. Intermediate levels of nutrients were found to be beneficial for sapling growth than high and low levels. This may be due to an increase in grass competition at higher levels of nutrients. Fires did not have a positive influence on sapling defence investment. To evaluate the relative importance of resource availability on sapling tree recruitment and its interactions with grass competition, I tested the effects of water (frequent irrigation vs. rainfall), shade (presence vs. absence), nutrients (addition vs. no addition) and grass competition (presence vs. absence) on sapling survival and growth under controlled field conditions in a humid South African savanna. Treatments did not have an effect on sapling survival, indicating that mortality is not defined by resource availability and grass competition in humid savannas. Shade had the greatest negative effect on sapling growth, suppressing the beneficial effects of nutrients and absence of grass competition. Nutrient limitation and grass competition had a relatively small influence on savanna sapling growth. Frequency of water availability had no effect on sapling growth, perhaps owing to high rainfall experienced over the experimental period. Therefore, canopy shade can be considered to be an important driver of tree dynamics in humid savannas with some degree of influence by nutrient availability and grass competition. The effects of clipping (i.e. simulated herbivory of grass and tree saplings) as influenced by nutrient availability and grass competition were examined on sapling survival and growth of all study species in a humid savanna. None of the treatments had an effect on sapling survival. This signifies that herbivory alone cannot significantly decrease plant density in humid savannas. However, tree saplings grew taller with a reduction in diameter and overall biomass, implying that saplings may become more susceptible to fires after herbivory. Nutrient addition and grass competition in general had a positive and negative effect, respectively, on sapling growth. This response was prominent in the stem length growth rates of defoliated saplings of one humid and two mesic species. These results imply that clipping (or herbivory) is the major factor reducing sapling vigour to establish, but is affected by both grass competition and nutrient availability. This study shows that fire has a differential effect on sapling survival of different species, particularly between humid savanna species. Light interception among all other resources limits the recruitment of saplings into adult size classes. Clipping, nutrient availability and grass competition had a relatively small direct effect, but may interact with other factors to alter sapling establishment dynamics. Wet-season droughts in humid savannas are not a hindrance to tree establishment because sapling survival was not dependent on frequency of rainfall. Thus, in humid savannas, fires can have a major impact on tree species density and composition while canopy shade has a very high potential to alter tree distribution. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Temperate Midwestern oak savannas are considered imperiled ecosystems with < 1 % remaining since the time of European settlement and are identified as critical areas for preservation. Restoration of Midwestern oak savannas is challenging due to the lack of accurate historical data, few intact remnants remaining to study, and lack of restoration ecology studies. A plant trait-based approach was used to evaluate the ability of six C3 and three C4 native bunchgrasses to restore functionality to a remnant savanna–woodland of the Bluegrass Region of Kentucky. The response and effect framework was used to assess the response of the nine native grasses according to the habitat filters of interannual precipitation, inter- vs. intra-specific competition, and simulated grazing. The effect traits associated with plant-soil nitrogen and carbon cycling were also assessed. The response traits of interannual competition and inter- vs. intra-specific competition along with the effect traits plant-soil nitrogen and carbon cycling were measured in a monoculture experiment conducted at Griffith Woods WMA. The simulated grazing or clipping experiment was conducted over three months in a heated greenhouse experiment. Four of the C3 species were of the genus Elymus which had significant differences in life history traits compared to the other species and made them particularly well adapted to the Bluegrass Savanna-Woodland. The Elymus species were not well adapted to the most intense clipping treatment. For the other two C3 species, C. latifolium would be a better competitor than D. clandestinum under normal conditions. D. clandestinum had the most number of plastic traits and was the only species to exhibit all three grazing strategies. Comparing the C4 species, T. flavus and P. anceps grew well in the monoculture but A. virginicus did not. The life history traits of A. virginicus does not make this species a good candidate for restoration at this site. The three C4 species were well adapted to clipping. The results of this study suggest that the C3 species, particularly the Elymus, are well adapted to the eutrophic mesic conditions of the Bluegrass Savanna-Woodland, and that the C4 species are better adapted to disturbance.

Surveys of plant and selected insect species was conducted in Highveld and Lowveld agro–ecosystems of four provinces of South Africa, namely North–West, Mpumalanga, KwaZulu–Natal and Limpopo. The objectives of the study were to compare insect and plant diversity between localities (grassland and savanna) and treatments (maize field, semi–transformed and untransformed) to test for a general relationship between plant and insect diversity along a maize field–field margin gradient. Plant and insect diversity patterns were studied along the gradient and quantified in terms of richness and diversity indices. Plant and insect species compositional turnover was also measured along the maize field–field margin gradient. Plant diversity increased with increasing distance from maize fields into the margin. The flora in maize fields and of margins differed, but in contrast, insect species assemblages were similar in maize fields and margins. There was no statistical difference in insect diversity between treatments (maize field, semi–transformed and transformed). A relationship was revealed between plant and insect diversity, as plant diversity enhanced insect diversity. / Thesis (M.Sc. (Environmental Sciences))--North-West University, Potchefstroom Campus, 2011.

Surveys of plant and selected insect species was conducted in Highveld and Lowveld agro–ecosystems of four provinces of South Africa, namely North–West, Mpumalanga, KwaZulu–Natal and Limpopo. The objectives of the study were to compare insect and plant diversity between localities (grassland and savanna) and treatments (maize field, semi–transformed and untransformed) to test for a general relationship between plant and insect diversity along a maize field–field margin gradient. Plant and insect diversity patterns were studied along the gradient and quantified in terms of richness and diversity indices. Plant and insect species compositional turnover was also measured along the maize field–field margin gradient. Plant diversity increased with increasing distance from maize fields into the margin. The flora in maize fields and of margins differed, but in contrast, insect species assemblages were similar in maize fields and margins. There was no statistical difference in insect diversity between treatments (maize field, semi–transformed and transformed). A relationship was revealed between plant and insect diversity, as plant diversity enhanced insect diversity. / Thesis (M.Sc. (Environmental Sciences))--North-West University, Potchefstroom Campus, 2011.

Considerable understanding of the functioning of semi-arid systems is still needed to enable range managers to formulate management policies, with a degree of confidence. Long term data sets that encompass a wide range of interactions between the various major components of a semi-arid system (vegetation, herbivory, animal performance, landscape and rainfall), are unfortunately rare but essential to provide sufficient depth of data to adequately test various hypotheses about rangeland dynamics. This study comprises an analysis of a ten year data set derived from two cattle stocking rate trials in the semi-arid savanna of KwaZulu/Natal. Statistical analysis revealed that the most pronounced and rapid compositional change was due to rainfall, but that stocking rates between 0.156 and 0.313 AU ha ¯¹ had an important effect as well. Sites on steeper slopes with heavy stocking rates, exhibited the greatest amount of compositional change between 1986 and 1996 (40 Euclidean points in heavy stocking rate treatments on slopes vs 21-24 Euclidean points in heavy stocking rate treatments on flatter land, or 11-24 Euclidean points in low stocking rate treatments). Heavy stocking rates in conjunction with low rainfall tended to cause decreases in densely tufted perennial grasses and increases in annuals and weakly tufted perennials. Multiple regression analysis revealed that seasonal peak grass production (measured as disc height) declined between 1986 and 1996 only at those sites on steeper slopes with heavy stocking rates. The camps that declined in productivity also underwent the greatest degree of compositional change. The decline in grass productivity in certain high stocking rate camps did not translate into a decline in cattle performance. Depending on rainfall, cattle gained on a seasonal basis between 112 and 241 kg at low stocking rates, 82 and 225 kg at medium stocking rates and 84 and 217 kg at high stocking rates Rainfall, compared with stocking rate, accounted for the greatest amount of variance in seasonal peak grass production and cattle performance. Cattle performance had a strong curvilinear response to rainfall, which also proved to be a better predictor of cattle performance than grass biomass. There were no clear trends in soil physical and chemical characteristics between low and high stocking rates that could provide convincing evidence that loss of soil nutrients was an important mechanism of range degradation. The total standing crop of plant nitrogen but not of phosphorus tended to decline at high stocking rates. Plant nutrient and van Soest analyses suggested that forage quality was higher at heavy stocking rates. The results of this study generally supported traditional concepts of rangeland dynamics with regard to rainfall and grazing effects on compositional change and seasonal grass production. The results were important in being able to show quantitatively that heavy stocking rates result in a decline in grass production and that this effect is dependent on an interaction between stocking rate and landscape position or slope, and that there is a link between a decline in seasonal grass production and compositional change. The results also highlighted areas for future research that would be useful for furthering our understanding of various aspects of rangeland dynamics and mechanisms of degradation. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

Made available in DSpace on 2016-06-02T19:32:02Z (GMT). No. of bitstreams: 1 4266.pdf: 343881 bytes, checksum: a843bc826f2ba420ebc775b291215df6 (MD5) Previous issue date: 2012-03-02 / Universidade Federal de Minas Gerais / Originality measures how different a given species is from all other species regarding either their phylogenetic history or functional traits and may be used to assign conservation priorities. This dissertation is divided into two chapters. In the first chapter, we introduced and defined the phylogenetic and functional originalities, which are still underused. We discussed the advantages of using this approach and showed how it could be used in conservation plans. In the second chapter, we analysed the relationships between phylogenetic, and functional originalities, their relationships with the environment, and their losses under extinction scenarios based on species abundance, fire tolerance, and habitat preference. We placed 100 plots in a cerrado reserve located in central Brazil, sampled all woody plants within the plots, measured 14 functional traits, and measured soil, topography, and fire. We assembled a phylogenetic tree, and a functional dendrogram, with which we calculated the originalities. Phylogenetic- and functional-based originalities were correlated, and both increased towards harsher environments. However, the loss of functional originality was different from random extinctions on the abundance and fire tolerance scenarios, whereas the loss of phylogenetic originality was not. Functional originality seemed to be a better surrogate to be used in conservation strategies, because it was sensitive to differences in species abundances and fire tolerance. / A originalidade mede o quanto uma dada espécie é diferente das outras espécies em uma comunidade com relação à sua história filogenética e aos seus traços funcionais, podendo ser usada para atribuir prioridades de conservação. Este trabalho está dividido em dois capítulos. No primeiro capítulo, nosso objetivo foi introduzir as originalidades filogenética e funcional, medidas ainda pouco conhecidas. Justificamos as razões para o uso dessa abordagem e exemplificamos maneiras de utilizá-la para fins conservacionistas. No segundo capítulo, nosso objetivo foi avaliar a relação entre a originalidade filogenética e a originalidade funcional, a relação de ambas com variáveis ambientais, e suas perdas em cenários de extinções baseados na abundância, tolerância ao fogo e preferência por hábitats, uma maneira objetiva para se tomar decisões com fins conservacionistas. Para isso, em uma reserva de cerrado no Brasil Central, lançamos 100 parcelas, amostramos o componente arbustivoarbóreo e medimos para cada indivíduo 14 traços funcionais. Para cada parcela, coletamos variáveis ambientais de solo, topografia e histórico de fogo. As originalidades filogenética e funcional estiveram correlacionadas, e ambas aumentaram em direção a ambientes mais severos. Entretanto, nas simulações de extinções baseadas na abundância e na tolerância de fogo, a perda de originalidade funcional foi diferente da perda em extinções aleatórias, enquanto que a perda de originalidade filogenética não foi. Originalidade funcional parece ser uma medida mais apropriada para ser utilizada em estratégias de conservação, já que foi sensível a diferença entre as espécies com relação a suas abundâncias e tolerância ao fogo.

Made available in DSpace on 2016-06-02T19:32:08Z (GMT). No. of bitstreams: 1 5490.pdf: 1141768 bytes, checksum: a5a2a49b5f220f5e424dbe6dc6784e42 (MD5) Previous issue date: 2013-08-14 / Universidade Federal de Sao Carlos / Algae are organisms with which studies have been made on the uptake of carbon dioxide, as a source of lipids for research on biofuels such as fertilizers and soil. But little is known about the interaction of such organisms with higher plants. Thus, the general objective of this master thesis was to reuse the algal biomass of Selenastrum capricornutum Printz (Chlorophyceae class) e Chlorella sorokiniana Shihira e Krauss (Trebouxiophyceae class) in pelleting seed Bowdichia virgilioides, native to the Brazilian Savanna that are classified as threatened with extinction and whose wood has attributes for the furniture industry, besides the medicinal properties already reported in other studies. First, the seeds were grown in a greenhouse, with the following treatments: a) seeds naked; b) pelleted seeds with white glue based on polyvinyl acetate diluted to 8% at water and gypsum; c) seeds pelleted with glue based white polyvinyl acetate diluted to 8% at wet algal biomass of Selenastrum capricornutum and gypsum; d) pelleted seeds with white glue based polyvinyl acetate diluted to 8% at wet algal biomass of Chlorella sorokiniana and gypsum. Fungicide and insecticide were added to the silicato and gypsum for agricultural according to industry directions. The parameters mean emergence time (days), weight (g) dry and cool, length (cm) of aerial and root portions and number of nitrogen fixing nodules in the roots don t showed statistically significant difference between treatments. The variable "emergency percentage" showed that pelleted seeds with C. sorokiniana biomass as a cement material constituent showed value equivalent to conventional treatment (naked), paving the way for new studies pelleting with agal biomass of that species. As higher be the algae intracellular biochemical values, higher be the chances to achieve satisfactory results, because the seed can be use algae biochemical components at its development. In a second stage, there was pelleted seed sown in an area of brazilian savanna and the treatments were: a) naked seed; b) pelleted seeds with white glue based on polyvinyl acetate diluted to 8% at water and gypsum; c) pelleted seeds with white glue based on polyvinyl acetate diluted to 8% at wet algal biomass of Selenastrum capricornutum and gypsum with fungicide and insecticide; d) pelleted seeds with white glue based on polyvinyl acetate diluted to 8% at water and silicate for agricultural; and e) pelleted seeds with white glue based on polyvinyl acetate diluted to 8% at wet algal biomass of Selenastrum capricornutum and silicate for agricultural. Fungicide and insecticide were added to the silicato and gypsum for agricultural according to industry directions. For this experiment hood, it was observed that treatment with only gypsum had a significantly lower percentage of emergence. The treatment with silicate was considered as an effective material coating to the sucupira seed pelleting process, cultivating in savanna field. Thus, the alga Chlorella sorokiniana showed to be an efficient cementing material for pelleting process and silicate for agricultural a promising coating material, when it comes to planting in the field. / Microalgas tem sido alvo em estudos que visam à captação de dióxido de carbono. Esses microrganismos também vêm sendo utilizados como fonte de lipídios para produção de biocombustíveis e estudos relatam sua biomassa como potenciais fertilizantes de solo. Mas, pouco se sabe sobre a interação de tais organismos com vegetais superiores. O objetivo geral desse trabalho foi reutilizar a biomassa de Selenastrum capricornutum Printz (classe Chlorophyceae) e Chlorella sorokiniana Shihira e Krauss (classe Trebouxiophyceae) na peletização de sementes de Bowdichia virgilioides (sucupira preta, sucupira do cerrado), espécie nativa do cerrado brasileiro que está classificada como ameaçada de extinção e cuja madeira possui atributos para a indústria moveleira, além das propriedades medicinais já relatadas em vários trabalhos. Primeiramente, as sementes foram semeadas em casa de vegetação, com os seguintes tratamentos: a) sementes nuas (sem pélete); b) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% em água e gesso agrícola; c) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% em biomassa algal úmida de S. capricornutum e gesso agrícola; d) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% com biomassa algal úmida de C. sorokiniana e gesso agrícola. Ao gesso agrícola foram acrescentados fungicida e inseticida. Tempo médio de emergência (dias), peso (g) seco e fresco, comprimento (cm) das partes aéreas e radiculares e o número de indivíduos contendo nódulos fixadores de nitrogênio nas raízes não apresentaram diferença estatística significativa entre os tratamentos. Contudo, as plântulas de sementes peletizadas com C. sorokiniana, como constituinte do material cimentante, apresentaram porcentagem de emergência equivalente ao tratamento convencional (nua). Observamos que quanto mais elevados forem os valores bioquímicos intracelulares da alga, há mais chances de obtermos resultados satisfatórios, já que a semente pode utilizar tais compostos em seu desenvolvimento. Em um segundo momento, a semeadura de sementes peletizadas foi realizada em uma área do cerrado situada no campus da Universidade Federal de São Carlos (21°57 S, 47°52 W, a 863 m de altitude), cidade de São Carlos-SP. Os tratamentos foram: a) sementes nuas (sem pélete); b) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% em água e gesso agrícola; c) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% em biomassa úmida de S. capricornutum e gesso agrícola; d) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% em água com silicato para uso agrícola; e) sementes peletizadas com cola branca à base de acetato de polivinila diluída a 8% em biomassa úmida de S. capricornutum e silicato para uso agrícola. Ao silicato e gesso para uso agrícola foram acrescentados fungicida e inseticida segundo as recomendações dos fabricantes. Para este experimento em campo, observou-se que o tratamento somente com gesso agrícola proporcionou uma porcentagem de emergência significativamente menor do que o tratamento sementes nuas , sendo o silicato considerado um material mais eficiente como revestimento no processo de peletização de sementes de sucupira do cerrado cultivadas em campo. Assim, a alga C. sorokiniana mostrou-se um material cimentante eficiente no processo de peletização e o silicato para uso agrícola mostrou-se um material de revestimento promissor, em se tratando de plantio em campo.

Made available in DSpace on 2016-06-02T19:32:16Z (GMT). No. of bitstreams: 1 DissPKA.pdf: 490127 bytes, checksum: 18f6cf8d6514765ac9c01c7df71da800 (MD5) Previous issue date: 2005-09-23 / Universidade Federal de Minas Gerais / The Cerrado Domain occupied formerly 2 million km2 of the Brazilian territory, especially in the Central Plateau. The cerrado vegetation is not uniform in physiognomy, ranging from grassland to tall woodland, but with most of its physiognomies within the range defined as tropical savanna. In cerrado, there are few areas that become waterlogged during the rainy season due to the poor drainage of the soil, allowing the appearance of a hyperseasonal cerrado, characterized by two contrasting stresses, one induced by drought and fire during the winter, the other by soil saturation in the summer. As long as soil is important in the ecology of the cerrado, limiting the cerrado distribution and the occurrence of its physiognomies, we investigated the soil-vegetation relationships in a cerrado core area in Emas National Park, in three vegetation forms: hyperseasonal cerrado, seasonal cerrado, and wet grassland. We collected vegetation and soil samples in these three vegetation forms and submitted obtained data to a canonical correspondence analysis. Our results showed a distinction among hyperseasonal cerrado, seasonal cerrado and wet grassland, which presented different floristic compositions and species abundances. The edaphic variables best related to the hyperseasonal and seasonal cerrados were sand, base saturation, pH, and magnesium. The wet grassland was related to higher concentrations of clay, organic matter, aluminium saturation, aluminium, phosphorus, and potassium. We also investigated the relationships between number of species and soil characteristics, with simple multiple linear regressions, and found that aluminium and pH were the best predictors of species density, the former positively related to species density and the latter negatively related. / O Domínio do Cerrado ocupava aproximadamente dois milhões de km2 do território brasileiro, especialmente no Planalto Central. A vegetação de cerrado não é uniforme em sua fisionomia, pois varia desde o campo limpo até o cerradão, mas a maior parte de suas fisionomias podem ser definidas como savana. Em algumas raras áreas de cerrado, a drenagem do solo é muito baixa, provocando o seu alagamento na estação chuvosa e favorecendo o surgimento de cerrados hiperestacionais, em que há dois períodos de estresse, um induzido pela seca e pelo fogo no inverno, e outro induzido pelo alagamento no verão. Como o solo é um dos principais fatores que controlam a distribuição do cerrado, além de ser determinante para a ocorrência das diferentes fisionomias que o compõem, nosso objetivo neste trabalho foi estudar a relação solo-vegetação em uma área nuclear de cerrado, no Parque Nacional das Emas (GO), em três ambientes: cerrado hiperestacional, cerrado estacional e campo úmido. Amostramos o solo e a vegetação desses três ambientes e comparamos algumas variáveis edáficas e vegetacionais por meio de análise de correspondência canônica. Nossos resultados apresentaram uma distinção florística entre o cerrado hiperestacional, o cerrado estacional e o campo úmido. As variáveis edáficas mais relacionadas com os cerrados hiperestacional e estacional foram porcentagem de areia, saturação por bases, pH e magnésio, enquanto que com o campo úmido foram argila, matéria orgânica, alumínio, saturação por alumínio e potássio. Também relacionamos o número de espécies em cada parcela com algumas variáveis edáficas, por meio de análises de regressão, e encontramos que o pH foi relacionado negativamente, e o alumínio, positivamente, com o número de espécies.