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trabalhos:abstracts [2021/05/27 00:46] jennifervasconcelosjdsv2 |
trabalhos:abstracts [2021/12/07 22:31] jennifervasconcelosjdsv2 |
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| ==== Dissertações de Mestrado ==== | ==== Dissertações de Mestrado ==== | ||
| + | === BEL, Renan Lucas Siena Del === | ||
| + | |||
| + | **Tree recruitment in a restinga rainforest: Influence of functional neighborhood and soil** | ||
| + | |||
| + | **Abstract:** While biological communities are complex systems in which numerous mechanisms act in different scales and different processes can generate the same pattern, one way to answer questions regarding the assembly of plant communities is to find correlations between environmental patterns indicative of underlying niche processes with the emerging patterns of a community. Because of that, it is essential to keep developing our understanding on how to represent the niche processes and how to better assess the community structure. In this dissertation we investigate how different environmental variables contribute to our understanding of niche processes. In particular, we are interested in how variables of biotic or abiotic nature interact and contribute to the pattern observed in the structure of the community, and whether the integration of these components is important in identifying the processes involved in community assembly. We use the spatially explicit leaf traits distribution of young (recruited in the last 10 years) individuals from a restinga in Ilha do Cardoso to represent the resulting pattern of the assembly processes, as well as data collected in 2009, to rebuild the neighborhood in which these individuals were recruited. We found that different combinations of biotic and abiotic variables explain different leaf traits distributions, but when we include the young individuals species as a random factor in our models, our results point for no correlation between environmental variables and leaf traits. Because of these conflicting results we infer that while both biotic and abiotic variables work together as predictors of the structure of the community, they do so via species distribution, which is in turn, correlated to an individual's leaf traits values. Thus, environmental variables are only informative when we have no information about the identity of the species. Based on our results, we propose that both types of variables (biotic and abiotic) must be used together when trying to assess the niche processes in a community, as both may be complementary and sometimes interact to form a more complete picture. Together our results open some lines of investigation that may further our knowledge over the mechanisms behind the tree community assembly and may inform future work in the field in order to achieve a better resolution in structure analyses. | ||
| === SOUZA, Luanne Caires da Cruz === | === SOUZA, Luanne Caires da Cruz === | ||
| Linha 187: | Linha 192: | ||
| **Abstract:**Many studies have been proving the importance of positive interactions to the distribution and diversity of species in plant communities. Positive and negative interactions occur simultaneously and the net effect of a species on another is the product of these combined interactions. The objetive of the present study was to evaluate if nitrogen fixing legumes facilitate other tree species in a nitrogen poor environment. We studied the effect of the presence of legumes on the density of species and individuals belonging to two different layers (DBH > 1 cm and 1≤ DBH ≥ 10 cm) around them and also patterns of spatial association between the legumes and other tree species, using a null models approach. The results obtained were dependent on the legume species considered. In chapter 1, the legume Balizia pedicellaris (DC.) Barneby & J.W.Grimes presented higher species density around it, for both layers, although there was no effect on the density of individuals. The species Ormosia arborea Harms did not present effect on the density of species and individuals around it. For the first layer Andira anthelmia (Vell.) J. F. Macbr. did not show effect on the densities, but this species presented a negative effect on the density of species and individuals of the upper layer (1 ≤ DBH ≥ 10 cm), in opposition to our hypothesis. In chapter 2, the spatial association patterns were also distinct between the legume species that showed different species identity associated and different kinds of association (positive or negative). The results indicate that, in spite of belonging to the same functional group, the legumes influence the species around them differently, depending on their morphological and physiological characteristics, as the ability to fix nitrogen in some systems or even the ability to produce alellopathic compounds. | **Abstract:**Many studies have been proving the importance of positive interactions to the distribution and diversity of species in plant communities. Positive and negative interactions occur simultaneously and the net effect of a species on another is the product of these combined interactions. The objetive of the present study was to evaluate if nitrogen fixing legumes facilitate other tree species in a nitrogen poor environment. We studied the effect of the presence of legumes on the density of species and individuals belonging to two different layers (DBH > 1 cm and 1≤ DBH ≥ 10 cm) around them and also patterns of spatial association between the legumes and other tree species, using a null models approach. The results obtained were dependent on the legume species considered. In chapter 1, the legume Balizia pedicellaris (DC.) Barneby & J.W.Grimes presented higher species density around it, for both layers, although there was no effect on the density of individuals. The species Ormosia arborea Harms did not present effect on the density of species and individuals around it. For the first layer Andira anthelmia (Vell.) J. F. Macbr. did not show effect on the densities, but this species presented a negative effect on the density of species and individuals of the upper layer (1 ≤ DBH ≥ 10 cm), in opposition to our hypothesis. In chapter 2, the spatial association patterns were also distinct between the legume species that showed different species identity associated and different kinds of association (positive or negative). The results indicate that, in spite of belonging to the same functional group, the legumes influence the species around them differently, depending on their morphological and physiological characteristics, as the ability to fix nitrogen in some systems or even the ability to produce alellopathic compounds. | ||
| + | |||
| + | === LACERDA, Victória Duarte === | ||
| + | |||
| + | **Structure and vegetation composition of a herbaceous-shrub mussununga in southern Bahia, Brazil** | ||
| + | |||
| + | **Abstract:** Mussununga is a vegetation type present in the Atlantic Forest, occurring on tablelands | ||
| + | in the north of Espirito Santo and southern Bahia. This vegetation occurs on patches of | ||
| + | white sandy soil embedded within forest areas and retains physiognomies similar to | ||
| + | restinga vegetation. This work was performed in a herbaceous/shrub Mussununga area | ||
| + | in southern Bahia, Brazil. Part of this area was subjected to a disturbance in the past due | ||
| + | to the cultivation of //Cocos nucifera L.//, however the cultivation was abandoned. The aim | ||
| + | of this study was to analyze the structure and composition of this plant community and | ||
| + | evaluate the floristic relationships with other areas. The first chapter covers only the | ||
| + | area with no evidence of recent disturbance. The structure and species composition of | ||
| + | this area was described and a floristic analysis was performed to verify similarity | ||
| + | patterns among 20 physiognomic similar areas occurring on white sand soils on the | ||
| + | Atlantic Coast of Brazil. We found 76 species in 37 botanical families and the richest | ||
| + | families were Fabaceae, Orchidaceae and Myrtaceae. The diversity was low | ||
| + | (h'=2.53nats), however the area presented a large environmental heterogeneity. | ||
| + | Floristic analysis showed a strong spatial correlation and low correlation with | ||
| + | environmental variables. In chapter 2, a portion of the area without evidence of recent | ||
| + | disturbance was compared to a portion of disturbed area based onrichness, diversity, | ||
| + | composition and the distribution of functional groups. Richness and diversity were | ||
| + | similar in both areas, however there was a remarkable difference in species | ||
| + | composition. The most abundant species in both areas was //Renvoizea trinii// (Poaceae). | ||
| + | The aggressive species //Pteridium arachnoideum// (Dennstaedtiaceae) increased | ||
| + | considerably in the disturbed area. Functional groups showed significant differences in | ||
| + | their mean coveragein each area. | ||
| === MORAES, Adriana de Olinda === | === MORAES, Adriana de Olinda === | ||
| Linha 244: | Linha 277: | ||
| **Abstract:** Composition is an important indicator of functional patterns of ecosystems, as it controls basic processes related to the availability of nutrients and to ecosystem productivity. Climatic and edaphic conditions and the quality of the litter and soil fauna as determining factors are of particular importance in the process of decomposition. The significance of each one of these varies with spatial and temporal scale. The objective of this work was to evaluate the importance of certain determining factors of decomposition in sites representing the main forest ecosystems of the state of São Paulo, Brazil. To accomplish this, two independent experiments were conducted. The first, denoted here as the Exotics experiment, was to examine the effects of the type of forest and the soil fauna on the decomposition of leaves of an exotic species (//Laurus nobilis L.//) in two humid forests (Restinga Forest of the Parque Estadual da Ilha do Cardoso e Atlantic Forest of the Parque Estadual Carlos Botelho) and a seasonal forest (Semideciduous Forest of the Estação Ecológica de Caetetus). The effects of these factors were tested above and belowground, to simulate the environment of decomposition among leaves and roots respectively. The type of forest had a significant effect over fauna above the surface, while below the surface, only fauna had significant effect. These results indicate that the hierarchy of determining factors in decomposition differs between leaves and roots. If on the one hand decomposition in leaves is much more susceptible to variation in climate than are roots, on the other hand changes in the soil fauna affect decomposition in both environments. Above the surface, fauna had a significant effect only in the Atlantic Forest, emphasizing the difference between two humid forests. Under the surface, and in the absence of fauna, the percentage of remaining biomass was very similar in the three forests. Notwithstanding differences in the forests, the presence of fauna was apparent, suggesting that there is a specific contribution of fauna in decomposition among roots in these forests. The Restinga Forest produced the most pronounced effect of fauna below the soil surface. These results indicate that fauna is a factor of notable importance in the decomposition of roots, especially in humid sandy tropical forests. The other experiment, here called the Native experiment, was developed to evaluate the effects of the substrate and the forest type on the decomposition of leaves of four native species in sites of the four major forest types in São Paulo state. The experiment was conducted in the same three forest sites as the Exotics experiment, including the Cerradão da Estação Ecológica de Assis. A tree species was chosen in each forest type, the leaves of which were used as substrate for the litter bags. The type of forest and the substrate demonstrated a significantly greater effect on the quantity of remaining mass throughout the experiment. The majority of the species suffered greater losses in the Atlantic Forest, followed by the Restinga Forest, the Semideciduous Forest, and the Cerradão. These results suggest that the total associated precipitation and its distribution are important determinants in the process of decomposition. As such, the two most humid forests show, on average, decomposition rates twice as great as the two seasonal forests. The rest of the differences encountered between forest types can be explained by edaphic and biotic factors. With respect to the effect of the species, the greatest biomass losses were observed in //Esenbeckia leiocarpa Engl.//, followed by //Copaifera langsdorfii Desf.//, //Guapira opposita Vell.// and //Calophyllum brasiliensis Camb.// Chemical parameters only show significant negative correlation with decomposition rates when G. opposita is excluded from the analysis. In this case the percentage of lignin was the parameter that showed the greatest correlation (r2= 0,59). In spite of the general patterns presented above, the interaction between forest type and substrate showed some variation, principally related to the loss of mass of C. langsdorfii in its native habitat, the Cerradão. Comparing decomposition rates (k) found in the Semideciduous Forest and Cerradão, //C. langsdorfii// shows a decrease of 40% more in the Cerradão, while the other species show, on average rates 28% lower in the Cerradão than in the Semideciduous Forest. These results suggest a strict correlation between the decomposition community and the local litter. Understanding processes of decomposition, is of fundamental importance and includes recognizing the determining factors and the variation in the importance of these factors under different environmental conditions, as presented in this study. This is true not only for our understanding of the forest ecosystems of São Paulo, but also for management planning, restoration, and conservation. | **Abstract:** Composition is an important indicator of functional patterns of ecosystems, as it controls basic processes related to the availability of nutrients and to ecosystem productivity. Climatic and edaphic conditions and the quality of the litter and soil fauna as determining factors are of particular importance in the process of decomposition. The significance of each one of these varies with spatial and temporal scale. The objective of this work was to evaluate the importance of certain determining factors of decomposition in sites representing the main forest ecosystems of the state of São Paulo, Brazil. To accomplish this, two independent experiments were conducted. The first, denoted here as the Exotics experiment, was to examine the effects of the type of forest and the soil fauna on the decomposition of leaves of an exotic species (//Laurus nobilis L.//) in two humid forests (Restinga Forest of the Parque Estadual da Ilha do Cardoso e Atlantic Forest of the Parque Estadual Carlos Botelho) and a seasonal forest (Semideciduous Forest of the Estação Ecológica de Caetetus). The effects of these factors were tested above and belowground, to simulate the environment of decomposition among leaves and roots respectively. The type of forest had a significant effect over fauna above the surface, while below the surface, only fauna had significant effect. These results indicate that the hierarchy of determining factors in decomposition differs between leaves and roots. If on the one hand decomposition in leaves is much more susceptible to variation in climate than are roots, on the other hand changes in the soil fauna affect decomposition in both environments. Above the surface, fauna had a significant effect only in the Atlantic Forest, emphasizing the difference between two humid forests. Under the surface, and in the absence of fauna, the percentage of remaining biomass was very similar in the three forests. Notwithstanding differences in the forests, the presence of fauna was apparent, suggesting that there is a specific contribution of fauna in decomposition among roots in these forests. The Restinga Forest produced the most pronounced effect of fauna below the soil surface. These results indicate that fauna is a factor of notable importance in the decomposition of roots, especially in humid sandy tropical forests. The other experiment, here called the Native experiment, was developed to evaluate the effects of the substrate and the forest type on the decomposition of leaves of four native species in sites of the four major forest types in São Paulo state. The experiment was conducted in the same three forest sites as the Exotics experiment, including the Cerradão da Estação Ecológica de Assis. A tree species was chosen in each forest type, the leaves of which were used as substrate for the litter bags. The type of forest and the substrate demonstrated a significantly greater effect on the quantity of remaining mass throughout the experiment. The majority of the species suffered greater losses in the Atlantic Forest, followed by the Restinga Forest, the Semideciduous Forest, and the Cerradão. These results suggest that the total associated precipitation and its distribution are important determinants in the process of decomposition. As such, the two most humid forests show, on average, decomposition rates twice as great as the two seasonal forests. The rest of the differences encountered between forest types can be explained by edaphic and biotic factors. With respect to the effect of the species, the greatest biomass losses were observed in //Esenbeckia leiocarpa Engl.//, followed by //Copaifera langsdorfii Desf.//, //Guapira opposita Vell.// and //Calophyllum brasiliensis Camb.// Chemical parameters only show significant negative correlation with decomposition rates when G. opposita is excluded from the analysis. In this case the percentage of lignin was the parameter that showed the greatest correlation (r2= 0,59). In spite of the general patterns presented above, the interaction between forest type and substrate showed some variation, principally related to the loss of mass of C. langsdorfii in its native habitat, the Cerradão. Comparing decomposition rates (k) found in the Semideciduous Forest and Cerradão, //C. langsdorfii// shows a decrease of 40% more in the Cerradão, while the other species show, on average rates 28% lower in the Cerradão than in the Semideciduous Forest. These results suggest a strict correlation between the decomposition community and the local litter. Understanding processes of decomposition, is of fundamental importance and includes recognizing the determining factors and the variation in the importance of these factors under different environmental conditions, as presented in this study. This is true not only for our understanding of the forest ecosystems of São Paulo, but also for management planning, restoration, and conservation. | ||
| + | |||
| + | =====Monografias (Iniciação Científica e trabalhos de conclusão de graduação)===== | ||
| + | |||
| + | **AULER**, Jennifer Prestes | ||
| + | |||
| + | **Environmental heterogeneity and the spatial distribution of Amazonia's trees** | ||
| + | |||
| + | **Abstract:** Niche and dispersal limitation are important coexistence mechanisms that can spatially structure tree communities. We aimed to verify the influence of environmental heterogeneity in the relative importance of those processes. We used data from ForestGEO plots with different environmental heterogeneity (Colombia-CO < Brazil-BR < Ecuador-EQ). We selected the most plausible of four concurrent spatial models: Randomness (CSR), Niche (NH), Dispersal Limitation (DL), and both (NH+DL). BR e EQ didn't diverge in the probability of model selection, having 85,6% and 83% of niche models selected (NH and NH+DL), while in CO only 57,5% were observed. The proportion of no model selected was four times higher in CO than in BR and EQ. We attribute these differences to CO's lesser environmental heterogeneity and conclude that it influences the relative importance of processes. Plots with a higher proportion of coexistence mechanisms are also significantly more diverse (BR and EQ > CO). | ||
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trabalhos/abstracts.txt · Última modificação: 2021/12/08 01:28 por jennifervasconcelosjdsv2
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