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trabalhos:abstracts [2021/05/26 23:51] jennifervasconcelosjdsv2 |
trabalhos:abstracts [2021/05/27 00:15] jennifervasconcelosjdsv2 |
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| **Abstract:** The objective of the current research was to investigate if the existing patterns in the adult tree communities can be generated by differences in the aspect related to the regeneration niche of species. Our model of study were two restinga's forests located at the Cardoso Island, on the South coast of São Paulo state. The tall resting forest (TRF) is an older formation, geologically speaking, and it hás closer canopies than the short resting forest (SRF). In the first chapter, we investigated if the abundance inversions of adult trees existing between the TRF and the SRF could be generated due to the differentiated performances of these species at the stage of the seedling, due to the action of the environmental light filter. We assumed as a hypothesis that the species show a worst performance in the stage of seedling in the forest where they are less abundant as adult, due to a trade-off between growth and survival. We expected that the mortality by pathogens was the main cause for the mortality of plants in the more shaded forest. We achieved a manipulative experiment in field with six tree species, in which one-month-old seedlings after germination were transplanted in the two forests and in the nursery. We followed the performance of the species in the two studied forests for nine months. There were no differences in the performance of the two species, except the survival of the Clusia criuva (in the expected way) and of the Tapirira guianensis (opposite to the expected way).Different from what was expected, the main cause of the mortality of all the species was the severe herbivory, and it was not possible to observe a conflict between the growth and the survival of them. In the second chapter, we investigated if the differences in the size of the seeds among the zoochoric tree species can generate differences in the patterns of the adult community and if those differences occur due to an action of the environment lighting filter or only by the differences of the dispersion capacity of the species. We followed the seed rain of the zoochoric tree species for four years in both forests and we could check that the active dispersion capacity of them is negatively related to the size of the seeds, as it can be predicted by both the hypothesis (environmental filter and dispersion capacity). Besides, the relationship between the average production of seeds and the size of the seeds presented a triangular pattern, as species with big seeds always provide low productions. We compared the seeds average sizes and the range of the seeds sizes of the individual plants and of the adult species in both forests (DAP_> 5 cm. We could verify that the TRF presents average size of seeds and range of the seeds's sizes that were bigger than in SRF. Furthermore, the SRF floristic composition is nested in the TRF composition. Therefore, we assumed as a hypothesis that the differences in the dispersal capacity of species, plus the age differences of the forests, are responsible for the distribution of the seeds sizes of the adult plants present in both forests. Finally, in chapter 3, we made a literature review about the role of the soil microorganisms in the specific site of the regeneration of the tropical tree species. We found studies that focus only on the action of the fungi as far in positive interactions (mycorrhizal fungi) as in negative ones (pathogenic fungi). We discussed the main factors and the characteristics associated to the mortality caused by the soil pathogens, as well as the relationship proposed by the pioneer studies which were not confirmed nor tested. | **Abstract:** The objective of the current research was to investigate if the existing patterns in the adult tree communities can be generated by differences in the aspect related to the regeneration niche of species. Our model of study were two restinga's forests located at the Cardoso Island, on the South coast of São Paulo state. The tall resting forest (TRF) is an older formation, geologically speaking, and it hás closer canopies than the short resting forest (SRF). In the first chapter, we investigated if the abundance inversions of adult trees existing between the TRF and the SRF could be generated due to the differentiated performances of these species at the stage of the seedling, due to the action of the environmental light filter. We assumed as a hypothesis that the species show a worst performance in the stage of seedling in the forest where they are less abundant as adult, due to a trade-off between growth and survival. We expected that the mortality by pathogens was the main cause for the mortality of plants in the more shaded forest. We achieved a manipulative experiment in field with six tree species, in which one-month-old seedlings after germination were transplanted in the two forests and in the nursery. We followed the performance of the species in the two studied forests for nine months. There were no differences in the performance of the two species, except the survival of the Clusia criuva (in the expected way) and of the Tapirira guianensis (opposite to the expected way).Different from what was expected, the main cause of the mortality of all the species was the severe herbivory, and it was not possible to observe a conflict between the growth and the survival of them. In the second chapter, we investigated if the differences in the size of the seeds among the zoochoric tree species can generate differences in the patterns of the adult community and if those differences occur due to an action of the environment lighting filter or only by the differences of the dispersion capacity of the species. We followed the seed rain of the zoochoric tree species for four years in both forests and we could check that the active dispersion capacity of them is negatively related to the size of the seeds, as it can be predicted by both the hypothesis (environmental filter and dispersion capacity). Besides, the relationship between the average production of seeds and the size of the seeds presented a triangular pattern, as species with big seeds always provide low productions. We compared the seeds average sizes and the range of the seeds sizes of the individual plants and of the adult species in both forests (DAP_> 5 cm. We could verify that the TRF presents average size of seeds and range of the seeds's sizes that were bigger than in SRF. Furthermore, the SRF floristic composition is nested in the TRF composition. Therefore, we assumed as a hypothesis that the differences in the dispersal capacity of species, plus the age differences of the forests, are responsible for the distribution of the seeds sizes of the adult plants present in both forests. Finally, in chapter 3, we made a literature review about the role of the soil microorganisms in the specific site of the regeneration of the tropical tree species. We found studies that focus only on the action of the fungi as far in positive interactions (mycorrhizal fungi) as in negative ones (pathogenic fungi). We discussed the main factors and the characteristics associated to the mortality caused by the soil pathogens, as well as the relationship proposed by the pioneer studies which were not confirmed nor tested. | ||
| + | |||
| + | === CARVALHO, Gabriel Martins de === | ||
| + | |||
| + | **Influence of stochastic processes on the structuring of community in tabuleiros forest, Bahia, Brazil** | ||
| + | |||
| + | **Abstract:** One of the central objectives of plant ecology is understand the factors that favor the | ||
| + | coexistence of large numbers of species in tropical forests. Previous studies have indicated that | ||
| + | species substitution (beta diversity) may explain the high diversities (alfa) seen in these | ||
| + | forests. Both determinist and stochastic processes can determine species distributions, thus | ||
| + | affecting the substitution rates of species in those communities. Within this context, the present | ||
| + | study evaluated variations in the composition and abundance of tree species, as well as their | ||
| + | morphometric attributes (diameter and height), between two habitat types in Tabuleiro Forests. | ||
| + | Tabuleiro Forests occur on wide coastal plateaus cut by occasional valleys. Edaphic and lightregime characteristics vary between these two topographic units, so that the tree communities | ||
| + | in each would be expected to be different.. A total of 1810 arboreal individuals of 349 | ||
| + | morphospecies DAP > 5 cm were sampled in ten 0.1 ha sampling plots. Comparisons were | ||
| + | made between the plateau and valley habitats in terms of their arboreal composition, structure | ||
| + | and physiognomy. Additionally, the occurrence of possible indicator species in these habitats | ||
| + | was examined. The most abundant species on the plateaus were //Manilkara multifida//, //Eugenia | ||
| + | rostrata//, //Rinorea guianensis// and //Paypayrola blanchetiana//, while //Actinostemon verticilatus//, //E. | ||
| + | rostrata//, //P. blanchetiana// and //Helicostylis tomentosa// were most abundant in valley sites. We | ||
| + | observed a high turnover of species among the plots, even within the same habitats, without the | ||
| + | occurrence of characteristic suites of species in any of them. No significant differences were | ||
| + | observed between the two habitats in terms of total abundance, diameters, tree heights, or total | ||
| + | basal areas. Only Croton macrobothrys among the 349 species sampled demonstrated any | ||
| + | significant association with valley habitats. The species distribution patterns observed suggests | ||
| + | that neutral mechanisms operate in structuring these communities, and that the bulk of the | ||
| + | species observed showed no discernable niche differentiation along the environmental gradient | ||
| + | analyzed. Differences were observed in the abundances of the species among the habitats, | ||
| + | however, exclusive species of a certain habitat were not observed. | ||
| === VAZ, Marcel Carita === | === VAZ, Marcel Carita === | ||
trabalhos/abstracts.txt · Última modificação: 2021/12/08 01:28 por jennifervasconcelosjdsv2
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