Banca de QUALIFICAÇÃO: MARINA VERGARA FAGUNDES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MARINA VERGARA FAGUNDES
DATA : 15/06/2019
HORA: 14:00
LOCAL: Sala de reuniões - DECOL
TÍTULO:

Functional traits of Caatinga seasonally dry tropical forest: species performance, functional strategies and restoration.

PALAVRAS-CHAVES:

Functional Strategies, Community assembling, Restoration, Functional niche, Semiarid Forests.

PÁGINAS: 95
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Functional traits are all physiological, morphological anatomical and biochemical features of an organism that allow it to survive and reproduce in its environment. The functional traits of organisms, here limited to tree species in a given region, are primarily selected by environmental filters. The understanding of how the environment modulates vegetation community is a worldwide question in Ecology. Once limited by environmental conditions, the functional traits will also exert effects on its environment, by changing abiotic resources and condition, affecting the surrounding organisms. Such effects can also modulate community structures. To understand both processes is fundamental to uptake not only general ecological patterns but to generate information on ecological theories, rebuilding communities in restoration programs. Mentioned that, we made this work, by now, with three independent chapters all focused on Seasonally Dry Tropical Forest Caatinga. The first chapter aims to analyze tree species coordinated trade-offs of one of the most biodiverse STDFs, determining functional groups, gathering above–below ground, and biochemical traits to test if there are shifts in traits strategies through growth stages. We sampled functional traits of 20 adult tree species in situ, and young plants of 2 and 6 months old cultivated in a greenhouse. We performed a PCA test, K-means and G-test analysis to respond to the previous questions, respectively. We found distinct coordinated trade-offs representing the slow–fast growth strategies continuum. This continuum was collapsed into two main groups of acquisitive and conservative strategies, and the majority of species were clustered within the conservative group. Finally, species presented more considerable variation of strategies at first growth stages than at adult stages, where traits variations tend to be lower, showing that despite the intrinsic high functional species diversity, the environment pressure lead species to increase its functional similarity through growth stages. The second chapter aims to test which functional traits are important to explain the facilitation capabilities of nurse plants, and if specific combinations of nurse–target functional traits explain the outcome of species–specific interaction. We performed an in-situ experiment with 60 adult plant–target tree species combination replicated five times. Using the already sampled functional traits as a predictive variable and plant neighbor performance as the response variable, we performed a GLMM followed by model selection. We found that both conservative and acquisitive species can cause positive effects and the outcome is highly dependent on the species matches. The positive outcomes, however, happened when the species exerting the effect fulfill the ecological requirements of its neighbors. At least, the third chapter aims to test the effect of niche overlap, diversity and composition on complementarity effects of semiarid rebuilt communities. We produced 4704 seedlings of 16 semiarid tree species using a new growing method. All individuals were planted in 155 experimental communities of 13 m X 18 m, with 32 individuals each. The experimental communities were built at five levels of diversity with distinct composition with three replicas each. The difference between biomass of monocultures and polycultures were used to calculate complementarity effect. Above and below ground traits of all species were sampled in order to calculate niche overlap. We performed a non-parametric multiple regression, using complementarity values as the response variable and niche overlap, species diversity and composition as predictive variables. The majority of plant species were more productive in polycultures. Communities with richness level of 2 and 4 species had significant lower production when compared with communities with 8 and 16 species, and niche overlap did not have significant effect on complementarity. Our study indicates that for initial stages of restoration in semiarid lands, an intermediate number of species might have the same effect on biomass production compared to a higher diversity level. Moreover, our study showed the complexity of measure niche overlap in all functional dimensions and its effects on complementarity, and the traits measured in our work might be more associated to adaptations to resist and survive on semiarid lands than biomass productivity. In restoration programs, the ecological effects happens in long–term, and they are likely to change through time. Thus, we highlight the importance of large–scale and long–term monitoring experiments in order to increase the reliability of restoration techniques.

MEMBROS DA BANCA:
Interno - 1837921 - ALEXANDRE FADIGAS DE SOUZA
Interno - 1678202 - CARLOS ROBERTO SORENSEN DUTRA DA FONSECA
Presidente - 1677189 - GISLENE MARIA DA SILVA GANADE