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trabalhos:abstracts [2021/05/27 00:46] jennifervasconcelosjdsv2 |
trabalhos:abstracts [2021/09/17 02:28] 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 === | ||
trabalhos/abstracts.txt · Última modificação: 2021/12/08 01:28 por jennifervasconcelosjdsv2
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