A influência da sazonalidade no padrão de riqueza de comunidades vegetais lenhosas situadas na região Neotropical
Carregando...
Data
2017-05-10
Autores
Borgiani, Renan [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Na presente dissertação, e em seu primeiro capítulo, estudamos duas comunidades de cerrado sensu stricto no Estado de São Paulo: a primeira localizada no município de Itirapina (Fazenda São José da Conquista) e a segunda em Santa Rita do Passa Quatro (Parque Estadual de Vassununga, Gleba Cerrado Pé de Gigante). Estabelecemos 10 transectos (2 x 50 metros) seguindo o método proposto por Gentry (1982), amostrando todos os indivíduos lenhosos com DAP > 2,5 cm. Verificamos que o método adotado permitiu amostrar estrutura e composição florística em cerrado sensu stricto, incluindo diferentes formas de crescimento vegetal. No segundo capítulo, investigamos a influência, principalmente da sazonalidade, no padrão de riqueza de espécies arbóreas (árvores e arbustos) e de lianas de vegetações situadas na região Neotropical, compilando 124 áreas do banco de dados de Gentry (http://www.mobot.org/MOBOT/research/gentry/transect.shtml), incluindo as duas áreas de estudo amostradas no primeiro capítulo. A diversidade de plantas na região tropical tem sido correlacionada com variáveis climáticas, particularmente com a distribuição da precipitação. A combinação entre ausência de sazonalidade e elevada precipitação estão relacionadas à maior riqueza de espécies. Nossa premissa é que, em locais com sazonalidade climática, os recursos e a produtividade primária são reduzidos, o que pode reduzir a riqueza de árvores e de lianas. Lianas tendem a ser mais resistentes à estação seca do que árvores em função de atributos fisiológicos, podendo apresentar aumento da riqueza em ambientes sazonais. Nossos resultados mostraram que lianas são mais ricas em áreas não sazonais, porém, observamos uma tendência no aumento da riqueza com o prolongamento da estação seca (de 1 a 4 meses), enquanto que a as espécies arbóreas são mais ricas em áreas que não apresentam sazonalidade na precipitação, apresentando relação negativa com a sazonalidade. A riqueza de lianas apresentou forte relação positiva com a riqueza de espécies arbóreas.
In the present dissertation, and in its first chapter, we studied two communities of cerrado sensu stricto in the State of São Paulo: the first one located in the Itirapina city (Farm São José da Conquista) and the second in Santa Rita do Passa Quatro (State Park of Vassununga, Gleba Cerrado “Pé de Gigante” Giant Foot). We established 10 transects (2 x 50 meters) following the method proposed by Gentry (1982), sampling all woody individuals with DBH> 2.5 cm. We verified that the adopted method allowed to sample structure and floristic composition in cerrado sensu stricto, including different forms of vegetal growth. In the second chapter, we investigated the influence, mainly of seasonality, on the richness of arboreal species (trees and shrubs) and woody climbers (lianas) located in the Neotropical region, compiling 124 areas of the Gentry database (http: // www. Mobot.org/MOBOT/research/gentry/transect.shtml), including the two areas of study sampled in the first chapter. The diversity of plants in the tropical region has been correlated with climatic variables, particularly with precipitation distribution. The combination of absence of seasonality and high precipitation are related to the greater species richness. Our premise is that, in places with climatic seasonality, resources and primary productivity are reduced, which can reduce woody species richness. Lianas tend to be more resistant to dry season than trees due to physiological attributes, being able to present increase of the richness in seasonal environments. Our results showed that lianas are richer in non-seasonal areas, however, we observed a trend in the increase of the richness with the prolongation of the dry season (from 1 to 4 months), while the tree species are richer in areas that do not present seasonality in precipitation, showing a negative relationship with seasonality. The richness of lianas showed a strong positive relation with the richness of tree species.
In the present dissertation, and in its first chapter, we studied two communities of cerrado sensu stricto in the State of São Paulo: the first one located in the Itirapina city (Farm São José da Conquista) and the second in Santa Rita do Passa Quatro (State Park of Vassununga, Gleba Cerrado “Pé de Gigante” Giant Foot). We established 10 transects (2 x 50 meters) following the method proposed by Gentry (1982), sampling all woody individuals with DBH> 2.5 cm. We verified that the adopted method allowed to sample structure and floristic composition in cerrado sensu stricto, including different forms of vegetal growth. In the second chapter, we investigated the influence, mainly of seasonality, on the richness of arboreal species (trees and shrubs) and woody climbers (lianas) located in the Neotropical region, compiling 124 areas of the Gentry database (http: // www. Mobot.org/MOBOT/research/gentry/transect.shtml), including the two areas of study sampled in the first chapter. The diversity of plants in the tropical region has been correlated with climatic variables, particularly with precipitation distribution. The combination of absence of seasonality and high precipitation are related to the greater species richness. Our premise is that, in places with climatic seasonality, resources and primary productivity are reduced, which can reduce woody species richness. Lianas tend to be more resistant to dry season than trees due to physiological attributes, being able to present increase of the richness in seasonal environments. Our results showed that lianas are richer in non-seasonal areas, however, we observed a trend in the increase of the richness with the prolongation of the dry season (from 1 to 4 months), while the tree species are richer in areas that do not present seasonality in precipitation, showing a negative relationship with seasonality. The richness of lianas showed a strong positive relation with the richness of tree species.
Descrição
Palavras-chave
Ecologia vegetal, Fitossociologia, Composição florística, Variáveis climáticas, Plant ecology, Phytosociology, Floristic, Environmental variables