Estratégias ecológicas com base no sistema LHS (leaf-height-seed) em plantas lenhosas ao longo de gradientes ambientais
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2012-03-28
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Universidade Federal de Goiás
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How environmental filters and niche differentiation acts in assembly rules and the importance
of ecological strategies in such process are unresolved questions in community ecology. We
choose a savanna-forest gradient to answer these questions. Such gradient is related with
variations in soil fertility, light and disturbance frequency. We used null models and LHS (leafheight-seed)
traits, including intraspecific variability, to investigate if niche based process are
acting in assemblages along the savanna-forest gradiente. We also investigated if diferente
ecological strategies are favored along this gradiente and which edaphic parameters affects
niche based process. We found evidence for environmental filtering in forest and savanna
assemblages: factors such as soil, light and disturbance affected observed values of functional
traits, which were more similar than expected by chance. However, environmental filters
selected plants with different trait values along the gradient, highlighting the use of different
ecological strategies depending of abiotic characteristics of each assemblage. In forest
assemblages competitive strategies were the most commom (higher mean values for the
three traits), suggesting that light is a stronger filter than soil nutrient availability. In savanna
assemblages smaller plants with smaller specific lead área co-occurred most often, suggesting
strategies focused on resource conservation. Furthermore, we found evidence for niche
differentiation process (represented by competition between co-occurring plants) only in
savanna: trait values were less similar than expected by the null model. Therefore, in such
assemblages, where soil fertility is smaller and disturbances are more frequente, niche
differentiation acts reducing competition and enabling the permanence of indidividuals in the
assemblage. We found, also, that, soil fertility, texture and aluminium-pH are good predictors
for both niche based processes. Althought other studies have found evidence for niche based
process structuring natural communities, our research provides a more complete investigation
about assembly rules, comprising important factors to assemblage dynamics simultaneously
such as intraspecific variability, different functional traits and the influence of specific factors
like soil.
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LAURETO, L. M. O. Estratégias ecológicas com base no sistema LHS (leaf-height-seed) em plantas lenhosas ao longo de gradientes ambientais. 2012. 39 f. Dissertação (Mestrado em Ecologia e Evolução) - Universidade Federal de Goiás, Goiânia, 2012.