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KARLA MONIQUE SILVA CARNEIRO
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Effect of ant guards on the reproductive output of four myrmecophilic plant species
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Orientador : ESTEVAO ALVES DA SILVA
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Data: 28/02/2020
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Mostrar Abstract
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In plant-ant interactions, plants provide extrafloral nectar as a food resource for ants and the latter act as plant guards. Issue less explored in ant-plant studies are (i) the distribution of ants on plant parts; (ii) the ant-plant mutualism on harsh seasons, such as Cerrado’s dry period; and (iii) the effect of ants on fruit set (in comparison to folivory). Here, by assigning plants as either ant-present or absent, we investigated the influence of ants on the fruit production of Bionia coriacea, Cochlospermum regium, Peixotoa tomentosa and Vigna firmula, all of which bloom during the Cerrado’s dry period (May to August). In these plants, the extrafloral nectar season coincides with the flowering phenology. We also recorded the spatial segregation of ants (on extrafloral nectaries, leaves, flowers, stem, buds and fruits) in order to examine its distribution pattern along the day. Camponotus crassus was the only ant species that consistently visited the plants. In general, a marked spatial segregation was noted, with ant visits concentrated on extrafloral nectaries. Ants rarely visited reproductive structure, but even so, ant presence on plants was related with increased fruit set. Plant species with ants experienced up to 55% gains in fruit set, in comparison to ant-absent treatments; nonetheless, in B. coriaceum, ant presence decreased fruit set by 11%. Our data shows that the outcomes of ant-plant relationships cannot be generalized, but in general, ants do benefit their plant partners. To conclude, we report two all new extrafloral nectary plants, C. regium and V. firmula.
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IGOR ARAÚJO DE SOUZA
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CLIMATE CHANGE: IMPACTS, ADAPTATION AND VULNERABILITY OF SOUTH AMAZON EDGE TREES AT HIGH TEMPERATURES
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Orientador : BEATRIZ SCHWANTES MARIMON
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Data: 02/03/2020
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Mostrar Abstract
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Understand the temperatures tolerance limits of plant leaves is essential on a warming planet, especially to predict changes in biodiversity, carbon stock, and interactions between vegetation and climate. Studies assessing the thermotolerance of native tree species are rare, which limits the ability to assess the risks associated with global warming. Here we investigated the leaf thermotolerance, strategies of leaves temperature regulation and possible responses to future warming of coocurrent tree species (Qualea parviflora Mart., Pseudobombax longiflorum (Mart.) A. Robyns, Hymenaea stigonocarpa Mart. ex Hayne e Vatairea macrocarpa (Benth.) Ducke.) in savannas (rocky cerrado and typical cerrado) and a forest (cerradão) on the southern amazonian border. We quantified the 50% loss of photosystem II function, maximum leaf temperature and its variation, air temperature, stomatal conductance and leaf functional attributes. To assess the impacts of future warming, we quantify the current thermal safety margin and future absolute leaf temperatures. Thermotolerance ranged from 46.7 °C to 50.9 °C between species, and was higher for forest individuals. Individuals with lower maximum leaf temperature presented higher thermotolerance, and we observed that different environmental conditions determine different thermotolerance values. We highlight that savanna-grown individuals, even though they have greater efficiency in leaf heat dissipation, are more vulnerable to extreme high-temperature conditions and therefore more likely to be negatively affected by global warming. We observed that thermal limits of some tropical species are near to the maximum temperatures experienced, which presupposes that these species may be severely affected by rising global temperatures. This vulnerability could lead to unexpected and drastic changes in species composition, structure, distribution and interactions that occur in different environments.
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3
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Luciana Januário de Souza
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EFFECTS OF DROUGHT ON THE LEAF AREA INDEX IN THE AMAZON-CERRADO TRANSITION
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Orientador : BEN HUR MARIMON JUNIOR
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Data: 20/03/2020
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Mostrar Abstract
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Climate change resulting from deforestation and global warming has been a major cause of biodiversity loss and environmental services in the remaining vegetation of the Amazon/Cerrado transition (ACT) (BONINI 2019). ACT vegetation is hyperdynamic, with high mortality and recruitment rates compared with the central areas of the two biomes (MARIMON et al., 2014). Consequently, these vegetations have great annual seasonality in the leaf area index (LAI) (FREITAG et al., 2018) and high sensitivity to climate variations, especially the extreme drought events recorded in recent years (MALHI et al., 2004; PHILLIPS et al., 2004; DE OLIVEIRA et al., 2017; PEIXOTO, et al., 2017). Therefore, major efforts are needed to fill knowledge gaps and subsidize conservation actions that take into account the ability of ACT forest and savanna species to respond to climate variations (MARIMON et al., 2006; SOLÓRZANO et al., 2012 ).
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IZABEL AMORIM DE SOUZA
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EFFECTS OF HABITAT LOSS ON SMALL MAMMAL POPULATIONS IN A CERRADO IN SOUTH AMERICA
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Orientador : DIONEI JOSE DA SILVA
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Data: 27/03/2020
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Mostrar Abstract
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Changes in landscape attributes lead to habitat loss, which is the reduction in the amount of native vegetation area available for species to survive and persist in the landscape. These landscape changes, such as habitat degradation, have been a serious problem for small mammals. Thus, the objective of this work is to investigate the effect of habitat loss on the abundance, extinction, body condition and functional traits of small mammals along a gradient of fragmented landscapes. Our results show that habitat loss can affect populations of small mammals, leading to population decline, until they reach an extinction threshold. This effect was more evident for Thrichomys pachyurus, who is a habitat specialist, who had both its abundance and occurrence affected as well as his body condition. Rhipidomys macrurus (specialists) showed no significant differences between the landscapes. Gracilinanus agilis (generalist) had a significantly greater abundance in areas with less than 50% vegetation, but its body condition was not affected as well as the other species. Generalists such as Didelphis albiventris and Thylamys macrurus did not show significant effects of habitat loss on any of the variables evaluated. These conclusions will be useful for future decisions on landscape management in this region.
Changes in landscape attributes lead to habitat loss, which is the reduction in the amount of native vegetation area available for species to survive and persist in the landscape. These landscape changes, such as habitat degradation, have been a serious problem for small mammals. Thus, the objective of this work is to investigate the effect of habitat loss on the abundance, extinction, body condition and functional traits of small mammals along a gradient of fragmented landscapes. Our results show that habitat loss can affect populations of small mammals, leading to population decline, until they reach an extinction threshold. This effect was more evident for Thrichomys pachyurus, who is a habitat specialist, who had both its abundance and occurrence affected as well as his body condition. Rhipidomys macrurus (specialists) showed no significant differences between the landscapes. Gracilinanus agilis (generalist) had a significantly greater abundance in areas with less than 50% vegetation, but its body condition was not affected as well as the other species. Generalists such as Didelphis albiventris and Thylamys macrurus did not show significant effects of habitat loss on any of the variables evaluated. These conclusions will be useful for future decisions on landscape management in this region.
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JOSIENE NAVES CARRIJO
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Functional Attributes as Indicators of Ecological Strategies for Savanna and Forest Wood Plants
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Orientador : EDDIE LENZA DE OLIVEIRA
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Data: 22/04/2020
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Mostrar Abstract
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The functioning of plant communities in different habitats depends both on the environment, acting as an environmental filter, and on the functional adjustments of the different species to environmental conditions. There are large gaps in knowledge regarding functional adjustments of vegetation at community and specific level. Therefore, we determine here the functional attributes of woody plants of two savanna environments of the Cerrado Biome occurring on different substrates: 1. Alluvial Cerrado (CA); 2. Typical Cerrado (TC). We hypothesized that the functional attributes of the community and species differ between the two environments, since the substrates of these environments differ in the availability of water and nutrients to plants. We sampled six attributes (LA, LT, SLA, SSD, Btrel and HTOT) from 101 common or exclusive species from each environment. Alluvial Cerrado plants have smaller leaf area and bark thickness, higher specific leaf area and wood density and less relative bark thickness and total maximum height. The species common to both environments have high phenotypic plasticity of attributes. Thus, we conclude that: 1. Thicker leaves, with larger specific leaf area in the Cerrado Alluvial, represent resource acquisition strategy, allowing the maximization of the photosynthetic rate; 2. Smaller and higher density plants have functional adjustments in response to lower water availability; 3. Thicker bark makes the typical Cerrado shrub species more resistant to burning. Thus, the structuring of woody communities in both environments depends on the functional adjustment of plants to water availability and intensity of burning.
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6
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TAYNÁ BARBOZA FERRARI
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Determinants of the genetic diversity of lizards in the Brazilian Cerrado
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Data: 22/05/2020
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Mostrar Abstract
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Geographic patterns of genetic diversity have the potential to provide a better understanding of natural populations demographic trajectory and the evolutionary processes that shaped biodiversity in complex biogeographic systems. Given the complex recent geologic and climatic history of the Neotropical region, elucidating these mechanisms is essential to provide a more complete evolutionary picture of its biodiversity. Here, we tested the influence of historical, ecological and environmental predictors in determining the genetic diversity of Brazilian Cerrado lizards. To this end, we compared populations that differed in altitude, distance from the center and periphery of the biome, and in areas with distinct stability levels of vegetation distribution over the time. We also used body size as a surrogate for dispersal potential of the different lizard species. We hypothesized that populations at higher altitudes, close to the center of the Cerrado, with larger body sizes and in areas of greater vegetation stability will depict higher levels of genetic diversity. We compiled mitochondrial DNA sequences from previously published works on 34 lizard species collected within the limits of the Brazilian Cerrado. We defined sampling units using the geographic location of the species and a Bayesian implementation of the general mixed Yule-coalescent model (bGMYC), a method that investigates species limits and estimates groups that are potentially evolving separately. Subsequently, we calculated nucleotide diversity, a metric used to measure the genetic diversity of each sample unit, which we termed “populations”. We used the variables altitude, distance to the center of the Cerrado, distance to the margins of the Cerrado, lizard snout-vent length, and the number of times that climatic changes altered the Cerrado landscape in vegetation terms as predictors of genetic diversity in a machine learning multivariate analysis using Random Forests. We also employed two powerful modelling tools (SPDE – Stochastic Partial Differential Equations, and INLA – Integrated Nested Laplace Approximation) to create hierarchical spatial models that allowed the estimation of genetic diversity for non-sampled regions. Our results indicate that populations at higher and lower altitudes have higher genetic diversity compared to populations at intermediate altitudes. In addition, populations further from the Cerrado’s periphery and with smaller body sizes exhibited higher genetic diversity. Finally, genetic diversity values were lesser explained by vegetation stability than any other variable. Hence, the environmental determinants and ecological characteristics of the species better explained the genetic diversity of lizards in the Brazilian Cerrado than the historical stability.
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7
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RODRIGO SILVA BENSI
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Fruit production in intact and fire-degraded forests in southeast Amazonia
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Data: 25/06/2020
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Mostrar Abstract
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With agricultural expansion in southeastern Amazonia, transitional forest areas between the Amazon and the Cerrado are becoming increasingly degraded. Forest fragmentation tends to increase their vulnerability to fire, one of the main vectors of mortality in tropical forests, and may contribute to the formation of degraded areas, savannization of areas and transformation of the Amazon biome into Cerrado. Here we seek to understand how the fruit production behavior of 81 forest species in the Amazon-Cerrado transition at Tanguro Farm in Querência-MT. We evaluated an area of 150ha divided into three plots, Control, Annual Burn (B1yr) and Annual Burn (B3yr), during a controlled fire experiment (2004- 2010) conducted by the Amazon Environmental Research Institute (IPAM) and after end of the fire experiment (2011-2018), to investigate fruit and seed production in these areas in order to understand how the forest behaves during burning, which is very common in our region. This paper gathers information regarding total production by area over the years, comparison between areas, seasonality and individual production by species. Concluding that the fire increases the mortality of individuals, therefore there is a decrease in the fruiting pattern for the burned areas. Although statistically insignificant we observed differences in areas over the years, differences between production sites such as edge and interior of the forest and changes in individual production by species.
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DEISY MARTINS DOS SANTOS
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HISTORICAL CONNECTION BETWEEN ATLANTIC FOREST AND AMAZON FOREST: PAST OR PRESENT?
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Data: 10/07/2020
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Mostrar Abstract
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One of the greatest challenges for Conservation Biogeography is to understand the geographic distribution of species, in addition to the ecological conditions in which species are surrounded in their evolutionary and survival capacity. Among these challenges, the Wallacean deficit, which represents the gaps in the knowledge of the geographic distribution existing in most of the taxa, is one of the greatest difficulties presented to ecological studies. Despite the extremely high biodiversity and being an attractive scenario for research, the Neotropical regions, object of the present study, are still little studied, being less understood in their ecological, evolutionary, historical and original aspects. The present study aims to verify the hypothesis that (i) the Amazon Forest and the Atlantic Forest established connection in more recent periods, after the Pleistocene, contradicting the current models of their distribution. For this purpose, the potential distribution modeling of the 3 fauna species indicated above will be used, in order to (ii) point out favorable environments for the occurrence of these species in the Cerrado, through the possible past connection between these biomes of forest formations
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DOUGLAS DA COSTA SANTOS
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Seasonal fluctuations and spatiotemporal variation of the Trichoptera community in intermittent stream
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Orientador : RICARDO KEICHI UMETSU
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Data: 27/08/2020
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Mostrar Abstract
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Variations in environmental conditions over space and time can affect the structure of the Caddisfly community. Studies that aim to verify seasonal and spatial fluctuations, are able to indicate changes that occur in the environment such as changes in land use, due to variations in the structure of the community, with the substitution of species. The objective of our work was to evaluate the effect of temporal / seasonal and limnological variations on the immature community of Caddisfly along a longitudinal gradient. Our hypothesis is that both the community structure and the limnological variables are affected by environmental variations. This study was carried out in the Bacaba stream, located in the municipality of Nova Xavantina-MT, in a transition area between Cerrado and the Amazon Forest. Collections were carried out over five years (2011 to 2016), with quarterly collections. We collected it in three portions of the stream continuum (nascent, intermediate and mouth) in 100 m linear transections, collecting substrate samples from the margins. The Caddisfly community was affected by both longitudinal (spring, intermediate and mouth), temporal (2011 to 2016) and seasonality (drought and rain) variations. The abundance differed between all the collection points as well as between the dry and rainy periods. The wealth presented a difference between the source and the mouth, being also different between the periods of the year. The composition was also different between the years, with 2016 being the least rich and abundant. Both wealth and abundance showed a positive relationship with dissolved oxygen and a negative relationship with ammonia. The results of this study allowed us to conclude that the immature community of Caddisfly present in Cerrado stream is sensitive to changes in the environment, climate and chemical composition of the water, indicating that they are excellent bioindicators of water quality and can be used in environmental monitoring and water quality for human populations.
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ROSANGELA GAMA STRUTZ
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Zooplankton community structure streams of gallery forest and streams of veredas in Cerrado regions, Alto Araguaia, Brazil
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Data: 18/11/2020
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Mostrar Abstract
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The streams of gallery forest and veredas are two aquatic ecosystems associated with two important phytophysiognomies of the Brazilian Cerrado Biome. These ecosystems are little explored with few studies focused on zooplankton fauna. Thus, this study aimed to answer the following questions: (i) What is the composition of zooplanktonic species of rotifers, cladocerans and copepods in gallery forest streams and veredas? (ii) Are the richness, density, diversity and composition of zooplankton species of rotifers, cladocerans and copepods different between streams of gallery forest and streams of veredas? (iii) Does environmental variables (limnological and structural) influence the richness, density and composition of zooplankton species in streams of gallery forest and streams of veredas? Data collected between the years 2016 and 2017 from 25 streams of gallery forest and 16 streams of veredas in the Upper Araguaia river basin. The total richness in gallery forest streams was 75 taxa, with 52 taxa from Rotifera, 17 taxa from Cladocera and three orders from Copepoda (Calanoida, Cyclopoida and Harpacticoida). In streams of veredas the total richness was 53 taxa, with 39 taxa of Rotifera, nine taxa of Cladocera and two orders of Copepoda (Cyclopoida and Harpaticoida). The streams of the paths have less richness, less density and diversity and different taxon composition than streams of gallery forest. Only density was significantly related with environmental variables. Conductivity was the most important variable for streams of gallery forest. Meanwhile temperature, depth, flow, stream width and percentage of grasses were more important for streams of veredas. The difference between the richness and the composition of taxa between the two ecosystems may be related to the fact that streams of paths are spatially more isolated.
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LUCAS HEBER MARIANO DOS SANTOS
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Border and fire effects on community regeneration in a forest in the Amazonia-Cerrado transition
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Data: 30/11/2020
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Mostrar Abstract
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Understanding how forests and their edges behave after fire events is of the utmost importance, as it allows for a better understanding of the feedbacks that maintain the process of forest degradation beginning at the edge and advancing into the forest. However, most studies do not consider the interrelationship of disturbance that normally occur. In addition, often in studies of vegetation response to disturbances, studies do not focus on small individuals who can provide direct information about the succession process. In this study we evaluated the effects of three experimental burn regimes (unburned, burned annually and burnt three times) nine years after the last fire, from different distances to an agricultural border and canopy structure using LIDAR metrics on the diversity of two strata (Seedling: <1 cm; saplings: <5 cm in diameter) of the regenerating community of three areas in the Amazon-Cerrado transition using regressions. We found that although burnt stands regained richness compared to unburned control, the composition changed completely with the edge species advancing into the forest, this composition being controlled by the crown characteristics and distance from the edge. In addition, we found that the canopy structure is highly related to edge distance, independent of burn regime, with the lowest and least complex canopy near the edge. There was no difference in the average proportion of lianas per plot among the seedling areas, but in saplings, the area burned annually outperformed the others. In addition, the proportion of lianas per plot generally increased away from the seedling border and the tree fell. Seedling liana abundance was also higher in the unburned control, while in trees, treatments and distance to the edge had no effect on abundance. These responses point to complex patterns of degradation with various disorders interacting and acting at the same time. We conclude that the time since the last burn was not sufficient to recover the burned forests and that the distance to the edge creates a compositional gradient that allows some species to advance into the forest during the post-disturbance recovery period.
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Ana Clara Abadia Rodrigues de Sousa
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Diversity patterns and drivers of woody savanna communities on different substrates
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Orientador : EDDIE LENZA DE OLIVEIRA
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Data: 17/04/2020
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Mostrar Abstract
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In the Cerrado biome, a composition and structure of woody vegetation can be influenced by different factors that act in different spaces, especially between physiognomies with markedly different soils, such as the Typical Cerrado (CT) used on flat, deep and well-drained soils. , while the Cerrado Rupestre (CR) can establish in accidental relief, shallow soils and with rocky herring. In this study, we investigated how woody plants from two savanna environments, distinguishable by the type of substrate on the causes (CT and CR), which respond to regional (scalable and topographic) and local (edaphic properties) gradients, and determined the limits ecological changes and points of change at the community and population level. In addition, it is also available as changes in the composition and beta diversity of species, as well as changes in edaphic properties, considering two distinct environments (Cerrado Rupestre and Cerrado Típico). Our results revealed that the TC and CR environments have different ecological limits and points of change in the food and population level, considering the woody plants, both on a regional and local scale. We also show that there is a clear dissimilarity of the woody flora between CT and CR savannas, although the chemical and granulometric properties of the soil surface layers are not different between these environments. We also found that a beta diversity of the woody flora between the environments of both environments is exclusive for the replacement of species, with the most marginalized and central of the Biome being the ones that most contributed to a beta diversity. These results demonstrate that the editorial and topographic variability in the environments seems to have been more effective in explaining how changes in the responses of the communities that predict them are scalable. Our findings also revealed that, for the first time, the beta diversity standards for a woody flora in these environments are high due to the high substitution of species among communities. We believe that the high beta diversity is a reflection of the high floral variation of the woody plants, which exhibits unique flora among the sampled locations, due to their geographic and topographic characteristics, and not only due to the edaphic characteristics.
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WESLEY JONATAR ALVES DA CRUZ
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Functional structure in communities and ecological strategies of trees in Amazonia-Cerrado transition
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Orientador : BEATRIZ SCHWANTES MARIMON
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Data: 20/07/2020
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Mostrar Abstract
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The classification of plant species according to their function is an effective alternative to address ecological questions and responses of vegetation in relation to the physical environment. Understanding the importance of the variability of species strategies and functions requires the quantification of plant traits on a large scale. In this study we investigated the regenerative functional structure, trade-offs, ecological strategies and the intraspecific trait variability in a wide vegetation gradient between the Amazon and the Cerrado. We used a database composed of more than 80,000 records of functional attributes of almost 200 tree species in 39 permanent plots established in typical cerrado, cerradão, gallery forest, semideciduous seasonal forest, evergreen forest and open rain forest to answer the following questions: 1) What are the regenerative strategies and their influence on the structure of these different types of vegetation? 2) How does the functional structure change and what are the main trade-offs and strategies of the main tree species in the Amazon-Cerrado transition? 3) Is the intraspecific trait variability an indicator of better performance in forest and savanna species in multiscale? Our results showed that the species regenerative strategies are based on dry fruits dispersed by the wind or fleshy fruits dispersed by animals, being the most important zoocoria in all types of vegetation. We discovered the existence of remarkable strategies for resource use and survival in different types of vegetation. Strategies that change following the gradient from savanna and typical vegetation in the Cerrado to forest and typical in the Amazon. We record evidence that the intraspecific trait variability guarantees population growth and productivity on a regional scale. We conclude that the traits of fruits and seeds provide mechanisms for the tree species to reestablish themselves and the diversity of these characteristics can favor communities in each type of vegetation, which will allow them to withstand extreme environmental conditions. The morphological traits of leaves, bark and branches allowed us to identify ecological strategies and to classify the types of vegetation along the Amazon-Cerrado transition. We also found that not only the value of traits, but the magnitude of intraspecific variability influences the establishment and gain of aerial biomass, consequently causing an effect on local and regional demographic patterns. Our results provided indicators for predicting the response of the evaluated communities to possible environmental impacts, especially climate change, enabling better management and conservation of tree species.
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4
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MAYRA LAYRA DOS SANTOS ALMEIDA
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Conservation of natural areas: A potential strategy to increase the ecosystem service of pollination in soybean and sunflower crops
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Orientador : MONICA JOSENE BARBOSA PEREIRA
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Data: 02/09/2020
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Mostrar Abstract
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Human activities resulting from the intensification of agricultural in the state of Mato Grosso, have caused habitat loss, resulting in fragmented landscapes, formed by remnants of native vegetation, kept as a Legal Reserve (LR), surrounded by extensive monoculture. This change can drastically affect the pollination service provided by bees in native and cultivated areas. To understand the contribution of LR to the preservation of pollinators and consequently to the yield of soybean and sunflower crops this research was structured in three chapters with the following objectives: (1) to evaluate the role of the Cerrado as a natural support habitat for bees that provide sunflower pollination services and the contribution of pollinators to the yield of this crop; (2) to verify the influence of habitat amount and proximity to natural habitats on composition, richness and abundance of bees in adjacent sunflower crop and; (3) to evaluate the contribution of bees from Cerrado to the soybean crop yield. In the first chapter we show that the bees present in the Cerrado visit the sunflower plantation, and increase the crop yield. In chapter II, when evaluating different agricultural landscapes (natural habitat x sunflower), we showed that species richness and abundance of bees showed a positive relationship with the amount of habitat , decreasing with the increase of the distance from the crop to the natural habitat edge. In addition, we also showed that the weight of sunflower seeds varied with the distance from the natural habitat. In chapter III, when evaluating the service provided by bees from Cerrado in the pollination and soybean crop yield, we found that the plants exposed to pollinators showed a 20% increase in the production of pods and seeds. We emphasize that in this study the number of bee species was high, both in natural areas and crops, indicating the importance of preserving areas of Legal Reserve to guarantee both pollinator biodiversity and the pollination services.
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GABRIEL DOS SANTOS CARVALHO
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Natural and applied biological control: influence of native vegetation fragments and releases from Trichogramma pretiosum (Riley, 1879) in lepidoptera-pest parasitism in soybean crop
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Orientador : MONICA JOSENE BARBOSA PEREIRA
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Data: 04/09/2020
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Mostrar Abstract
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The agricultural expansion of soy favors the appearance of pests and the reduction of areas of natural vegetation, compromising the ecosystem services provided by beneficial insects. The control of these pests occurs through insecticides, which impact human health and the environment, in addition to harming their natural enemies. In this sense, the present thesis evaluated the influence of native habitats and flooding releases of Trichogramma pretiosum (Riley) on the parasitism of soybean pest lepidopterans. Therefore, in chapter I we evaluated, in an area, whether the distance of cultivation in relation to the Cerrado fragment interferes in the richness, abundance and rate of parasitism of lepidopteran pests by Ichneumonoidea. We observed that the distance of cultivation in relation to the edge did not affect the diversity of Ichneumonoidea, abundance and rate of parasitism, but it did influence the abundance of caterpillars, with the lowest average closest to the fragment. The diversity of Ichneumonoidea was greater in the off-season and in the vegetative. The most abundant subfamilies were Ichneumoninae, Microgastrinae, Macrocentrinae and Cremastrinae. In the second chapter, we verify whether the parasitism rate and abundance of soybean pest lepidopterans were affected by the distance and amount of natural habitat, amount of pasture and total cultivated area, in different cultivation areas. We verified that the distance affected the parasitism of the caterpillars, increasing as it approaches the natural habitat; the amount of this does not interfere with the rate of parasitism, but has significant interaction with distance. The abundance of caterpillars was not affected by distance, but was benefited by the other metrics (amount of natural habitat, amount of pasture and cultivated area). In the third chapter, we evaluated the effect of different proportions of T. pretiosum (100,000; 200,000; 300,000 wasps / ha, control 1 = without release and without application; control 2 = without release and with application). All treatments with parasitoid release kept the caterpillar population below the control level, therefore, we recommend the use of 100,000 wasps / ha as it represents a lower production cost. These results are expected to contribute to subsidize the ecological management of caterpillars in soybean crops and thus reduce the risks to biodiversity.
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NORBERTO GOMES RIBEIRO JUNIOR
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Anatomy of tree species in southern Amazonia as a prediction of impacts of environmental changes
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Orientador : BEN HUR MARIMON JUNIOR
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Data: 08/09/2020
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Mostrar Abstract
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Many predicted climate changes have been materializing since the early 2000s. In addition to the increase in the average temperature of the planet, tropical regions, including the Amazon Rainforest, have undergone intense drought cycles with years of less precipitation and more pronounced temperature peaks. Concomitant to these climate changes, deforestation is advancing along the edges and the major highways in the Amazon, increasing the loss of biodiversity and the effects of environmental changes. The Amazon-Cerrado (TAC) transition to the south and southeast of the Amazon is a vast area particularly sensitive to climatic factors due to the high seasonality of rainfall. In this zone, the rapid substitution of native vegetation for pastures and agriculture has destroyed ecosystems with particular characteristics and important collaboration for the environmental balance by their ecosystem services. Throughout this thesis, we have highlighted the structural particularities of TAC tree vegetation and meridional Amazon, both in case studies when evaluating anatomical-functional attributes (AFA) of species with high occurrence in the vegetation, and with comparisons of communities from different locations and patterns of AFA that allow a greater or lesser degree of resistance to the stress generated by climatic seasonality. In this perspective, we evaluated 16 plant communities using samples of leaves and stems from 932 trees. We process these samples and measure morphological, anatomical and physiological characters that we relate to the environmental characteristics of each plant community. We found that the species are endowed with different strategies to resist the seasonality of the region. While Tachigalli vulgaris is endowed with low plasticity to climatic conditions and water availability, having an apparent physiological and non-structural regulation to stress, other species of greater frequency in the sampled communities (Amaioua guianensis, Chaetocarpus echinocarpus, Miconia pyrifolia, Ocotea guianensis, Sacoglottis guianensis, Trattinnickia glaziovii and Xylopia amazonica) are notably endowed with phenotypic plasticity, being attuned to the plasticity of the wood tissue anatomy. When considering tree communities, most of them present a great diversity of strategies to deal with seasonal water stress. The comparative Cerradão vs. gallery forest revealed that despite a higher proportion of investment in xeromorphic structures, the cerradão is not endowed with excessively xeric characters and the gallery forest is endowed with greater hydraulic efficiency with minimal investment (at least in the vast majority of species) in safety hydraulic against vessel embolism. As for the comparison of the upland forest communities, we verified an interaction between xeromorphism and variations in water availability generated by seasonality. Drier communities presented for the leaves greater thickness of adaxial epidermis, smaller stomata and greater thickness of the leaf wing; and for branches the hydraulic conductivity, the average lumen area, the density of the xylemic vessels, the length and thickness of the sclerenchymatic fiber wall also varied according to our predictions, with patterns that generate greater xeromorphism and consequent hydraulic safety in the communities more seasonal. The particular responses of species to environmental variations make it difficult to analyze communities, however we were able to better understand how different taxa react to environmental stressors and how communities shape themselves to withstand the tropical seasonality that has presented intense episodes with greater frequency. It is a fact that some species have leaf adaptations such as: increase in supraepidermal structures, epidermal thickening and parenchyma that allow greater regulation of water loss. But the increase in hydraulic safety due to less efficient and safer conducting vessels is almost unanimous. Although there is investment in xeromorphic attributes, we emphasize that these communities are at risk of major changes in their structure and composition due to the intensification of stressful climatic events.
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ANTONIO CARLOS SILVEIRO DA SILVA
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THE ROLE OF FIRE AND DROUGHT EVENTS ON THE SOIL MOISTURE DYNAMICS IN THE TRANSITIONAL FOREST BETWEEN AMAZONIA AND CERRADO
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Data: 23/11/2020
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Mostrar Abstract
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Soil moisture can both affect and be affected by possible trajectories of forests impacted by disturbances. In the Amazon – Cerrado transition forests, forest fires and extreme drought events have occurred with greater intensity and frequency. With that, we evaluated the post-fire impact on the water content in the soil (Volumetric Water Content - VWC) in a portion burned every three years (2004 to 2010) and another portion burned annually (2004 to 2010), in addition to the control plot. Our data collection covered the period from 2010 to 2018, which made it possible to assess the impacts of extreme drought from 2015-2016 on the water content in the soil in the three plots. To estimate the water content in the soil, we used and evaluated the quality of two methods: time domain reflectometer (TDR) and resistivity, both methods being calibrated using the gravimetric moisture content quantification technique (Gravimetric Water Content - GWC). We tested the hypotheses that (H1) the burnt plots present higher soil moisture in the first post-fire years (between 2011 and 2012) and a reduction in the following years, and (H2) the extreme drought event (between 2015 and 2016) caused a greater water deficit in the soil of the burnt plots. Our results showed that both methods used estimated soil moisture consistently. On the interannual scale, the post-fire soil moisture did not differ much from that recorded in the intact plot (H1). On the other hand, the reduction caused by drought in soil moisture was more intense in the burnt plots (H2), requiring more time to recharge the volume of water from the soil. In addition, forests, both burned and intact, increased water use in the dry season, suggesting that the stressful conditions of seasonal drought are imposing on woody trees a greater demand for soil water, which is accessed mainly from deep soil ( up to 8m). In this sense, the increase in forest fragmentation, widespread fires and extreme drought events may cause greater variability, and even abrupt reductions in soil moisture under transition forests in a short period of time, further increasing the uncertainties for the recovery of these degraded forests.
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