Diversidade taxonômica e funcional em uma comunidade vegetal campestre de Cerrado na Região Metropolitana de São Paulo
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Data
2019-03
Autores
Keller, Victor Camargo [UNIFESP]
Orientadores
Vieira, Elisa Hardt Alves [UNIFESP]
Tipo
Dissertação de mestrado
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Resumo
As formações campestres do Cerrado ainda são pouco valorizadas, apesar de possuírem alta riqueza e diversidade de espécies vegetais, com características únicas para sobreviverem em um ambiente oligotrófico com perturbações recorrentes. São necessários estudos que caracterizem esta vegetação e investiguem os processos por trás da manutenção da biodiversidade nesses
ecossistemas. O objetivo deste trabalho foi caracterizar a vegetação da fisionomia de campo sujo do Parque Estadual do Juquery, analisando os potenciais efeitos de perturbações antrópicas (fogo e visitação pública) sobre sua diversidade e estrutura, como forma de inferir sobre a origem natural e primária desta vegetação. Este estudo também caracterizou o uso de nitrogênio (N) edáfico por gramíneas nativas, avaliando o efeito da sazonalidade climática sobre a assimilação do N, procurando relacionar as habilidades de uso do N com a abundância das espécies no campo nativo. Foram contabilizadas 261 espécies de plantas na área estudada, sendo principalmente
espécies herbáceas com adaptações que conferem resistência a perturbações como o fogo. As espécies lenhosas de maior importância na comunidade pertenciam ao gênero Byrsonima (Malpighiaceae), enquanto as herbáceas mais importantes foram todas gramíneas, como Echinolaena inflexa e Tristachya leiostachya (Poaceae). Os resultados indicam que a comunidade vegetal não foi afetada pela visitação ou pelos incêndios dos últimos 5 anos. Com relação ao uso do N, há uma modulação da atividade de Nitrato Redutase (ANR) entre os compartimentos folha e raiz, variável com os períodos seco e úmido; sendo as folhas o sítio preferencial de redução no
período seco e as raízes no período úmido. Por outro lado, as concentrações de N-nitrato e ureídeos preponderaram na parte aérea das plantas, sem a interferência da sazonalidade. Há indícios de que as habilidades de redução do nitrato interferem na abundância das gramíneas do campo nativo estudado, onde espécies com baixa ANR tiveram valores de abundância equivalentes, enquanto aquelas com alta ANR foram as mais e menos abundantes. A alta riqueza e diversidade de espécies observada, associadas à presença de adaptações para resistir a perturbações e ambientes oligotróficos e sazonais indicam que a vegetação estudada possui uma
origem natural, independente da ação humana.
Cerrado's grassy formations are still undervalued, despite having high richness and diversity of plant species, with unique characteristics to survive in an oligotrophic environment with recurrent disturbances. Studies are needed to characterize this vegetation and to investigate the processes behind the maintenance of biodiversity in these ecosystems. The objective of this work was to characterize the vegetation of the campo sujo physiognomy of Juquery State Park, analyzing the potential effects of anthropic disturbances (fire and public visitation) on its diversity and structure, as a way of inferring about the natural and primary origin of this vegetation. This study also characterized the use of edaphic Nitrogen (N) by native grasses, evaluating the effect of climatic seasonality on the N assimilation, trying to relate N use abilities with native species abundance. A total of 261 species of plants were recorded in the studied area, mainly herbaceous species with adaptations that confer resistance to disturbances such as fire. The woody species of major importance in the community belonged to the genus Byrsonima (Malpighiaceae), while the most important herbaceous were all grasses, such as Echinolaena inflexa and Tristachya leiostachya (Poaceae). The results indicate that the plant community was not affected by the visitation or fires of the last 5 years. Regarding the use of N, there is a modulation of the Nitrate Reduction activity (NRA) between leaf and root compartments, variable with dry and wet periods; being the leaves the preferential site of reduction in the dry period and the roots in the humid period. On the other hand, the concentrations of N-nitrate and ureides preponderated in the aerial part of the plants, without the interference of the seasonality. There are indications that nitrate reduction abilities interfere with grass abundance in the studied native grassland, where species with low NRA had equivalent abundance values, while those with high NRA were the most abundant and least abundant. The high richness and diversity of species observed, associated to the presence of adaptations to resist perturbations and oligotrophic and seasonal environments indicate that the studied vegetation has a natural origin, independent of human action.
Cerrado's grassy formations are still undervalued, despite having high richness and diversity of plant species, with unique characteristics to survive in an oligotrophic environment with recurrent disturbances. Studies are needed to characterize this vegetation and to investigate the processes behind the maintenance of biodiversity in these ecosystems. The objective of this work was to characterize the vegetation of the campo sujo physiognomy of Juquery State Park, analyzing the potential effects of anthropic disturbances (fire and public visitation) on its diversity and structure, as a way of inferring about the natural and primary origin of this vegetation. This study also characterized the use of edaphic Nitrogen (N) by native grasses, evaluating the effect of climatic seasonality on the N assimilation, trying to relate N use abilities with native species abundance. A total of 261 species of plants were recorded in the studied area, mainly herbaceous species with adaptations that confer resistance to disturbances such as fire. The woody species of major importance in the community belonged to the genus Byrsonima (Malpighiaceae), while the most important herbaceous were all grasses, such as Echinolaena inflexa and Tristachya leiostachya (Poaceae). The results indicate that the plant community was not affected by the visitation or fires of the last 5 years. Regarding the use of N, there is a modulation of the Nitrate Reduction activity (NRA) between leaf and root compartments, variable with dry and wet periods; being the leaves the preferential site of reduction in the dry period and the roots in the humid period. On the other hand, the concentrations of N-nitrate and ureides preponderated in the aerial part of the plants, without the interference of the seasonality. There are indications that nitrate reduction abilities interfere with grass abundance in the studied native grassland, where species with low NRA had equivalent abundance values, while those with high NRA were the most abundant and least abundant. The high richness and diversity of species observed, associated to the presence of adaptations to resist perturbations and oligotrophic and seasonal environments indicate that the studied vegetation has a natural origin, independent of human action.