Banca de QUALIFICAÇÃO: JOSÉ LUIZ ALVES SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : JOSÉ LUIZ ALVES SILVA
DATA : 21/03/2018
HORA: 13:00
LOCAL: SALA DE REUNIÕES DO CB
TÍTULO:

UNDERSTANDING PLANT FUNCTIONING, PLANT COMMUNITY ASSEMBLY, AND THEIR EFFECTS ON THE RESTINGA ECOSYSTEM

PALAVRAS-CHAVES:

Dunes, stressful environment, seasonally dry forest, biochemistry, leaf anatomy, primary productivity

PÁGINAS: 104
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Plant form and function in ecosystems depend on internal stimuli (genetics and phenotypic plasticity) as well as external stimuli (environment) on the distinct organs. The poor water and nutrient availability in sandy soils of the Northeastern region, combined with high radiation and seasonality, are cited as the main external stimuli in the Restinga ecosystem. The hypothesis that stressful environments require high coordination among leaf, stem and root traits has found some support, although it has not been widely tested. The first thesis chapter aimed to understand the functioning of Restinga plants considering the hypothesis of stress versus trait coordination. A multivariate analysis showed high independence among 21 functional traits of 21 species, suggesting that stressful environments do not necessarily select plants with high functional coordination. These results were published in the Ecology and Evolution in 2017. Functional coordination is directly linked to the success of plant occurrence and, thus, may interfere in the community assembly. It is still unclear whether species’ response, species interaction, dispersion, and neutral processes have similar effects on traits, phylogenetic relationships, and species occurrence. We evaluated these aspects in the second thesis chapter. We used 19 traits of 30 species, and 13 abiotic variables to detect possible functional patterns, despite the strong mismatch between phylogenetic relationships, occurrence and environmental heterogeneity found previously for the study region. Functional variation resulted from phenotypic response of all species and individuals rather than particular sets of species or individuals. We concluded that analysis of occurrence and phylogeny may be insufficient for a complete understanding of community assembly and should be complemented with trait analysis. Results were recently submitted in the Journal of Vegetation Science. Weak trait coordination and weak environmental responses may result from low relevance of niche partitioning among species, which has been described as the main mechanism linking biodiversity and ecosystem processes. The third thesis chapter aimed to assess the extent the biodiversity and environment influence the magnitude and stability in litterfall production, as well as the role of rare and abundant species, and the traits related to species’ productivity. Phylogenetic evenness, functional dispersion, richness and canopy cover represented some aspects of biodiversity. Elevation and nitrogen were the environmental predictors. A path analysis revealed that canopy cover had the greatest influence on magnitude, followed by species richness. Other predictors had only indirect effects. Stability did not respond to any predictor. In addition, the increase in species’ basal area and abundance increased magnitude, although some dominant species were compared to rare ones, probably because they have efficient stress-tolerance strategies that help them to hold biomass for a longer period. The most efficient strategy included the ability to have the best water control without requiring high production and energy reserve on leaves. These results suggest that biodiversity in tropical forests can affect the ecosystem differently from general predictions, and that its effects depend on the niche mechanism. The third chapter was not finished yet. Studying the Restinga ecosystem allowed me to discover patterns that deviate from general expectations, which highlights the singularity and relevance of its biodiversity.

MEMBROS DA BANCA:
Presidente - 1837921 - ALEXANDRE FADIGAS DE SOUZA
Interno - 983.396.135-53 - HELDER MATEUS VIANA ESPÍRITO-SANTO - INPA
Externo ao Programa - 233.792.888-88 - KEMAL ALI GER - UFRN