Banca de DEFESA: NORBERTO GOMES RIBEIRO JUNIOR

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : NORBERTO GOMES RIBEIRO JUNIOR
DATA : 08/09/2020
HORA: 08:00
LOCAL: Sala de aula do PPG-EC
TÍTULO:

Anatomy of tree species in southern Amazonia as a prediction of impacts of environmental changes

PALAVRAS-CHAVES:

Phenotypic plasticity, functional attributes, climate change, precipitation, soil moisture.

PÁGINAS: 132
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Many predicted climate changes have been materializing since the early 2000s. In addition to the increase in the average temperature of the planet, tropical regions, including the Amazon Rainforest, have undergone intense drought cycles with years of less precipitation and more pronounced temperature peaks. Concomitant to these climate changes, deforestation is advancing along the edges and the major highways in the Amazon, increasing the loss of biodiversity and the effects of environmental changes. The Amazon-Cerrado (TAC) transition to the south and southeast of the Amazon is a vast area particularly sensitive to climatic factors due to the high seasonality of rainfall. In this zone, the rapid substitution of native vegetation for pastures and agriculture has destroyed ecosystems with particular characteristics and important collaboration for the environmental balance by their ecosystem services. Throughout this thesis, we have highlighted the structural particularities of TAC tree vegetation and meridional Amazon, both in case studies when evaluating anatomical-functional attributes (AFA) of species with high occurrence in the vegetation, and with comparisons of communities from different locations and patterns of AFA that allow a greater or lesser degree of resistance to the stress generated by climatic seasonality. In this perspective, we evaluated 16 plant communities using samples of leaves and stems from 932 trees. We process these samples and measure morphological, anatomical and physiological characters that we relate to the environmental characteristics of each plant community. We found that the species are endowed with different strategies to resist the seasonality of the region. While Tachigalli vulgaris is endowed with low plasticity to climatic conditions and water availability, having an apparent physiological and non-structural regulation to stress, other species of greater frequency in the sampled communities (Amaioua guianensis, Chaetocarpus echinocarpus, Miconia pyrifolia, Ocotea guianensis, Sacoglottis guianensis, Trattinnickia glaziovii and Xylopia amazonica) are notably endowed with phenotypic plasticity, being attuned to the plasticity of the wood tissue anatomy. When considering tree communities, most of them present a great diversity of strategies to deal with seasonal water stress. The comparative Cerradão vs. gallery forest revealed that despite a higher proportion of investment in xeromorphic structures, the cerradão is not endowed with excessively xeric characters and the gallery forest is endowed with greater hydraulic efficiency with minimal investment (at least in the vast majority of species) in safety hydraulic against vessel embolism. As for the comparison of the upland forest communities, we verified an interaction between xeromorphism and variations in water availability generated by seasonality. Drier communities presented for the leaves greater thickness of adaxial epidermis, smaller stomata and greater thickness of the leaf wing; and for branches the hydraulic conductivity, the average lumen area, the density of the xylemic vessels, the length and thickness of the sclerenchymatic fiber wall also varied according to our predictions, with patterns that generate greater xeromorphism and consequent hydraulic safety in the communities more seasonal. The particular responses of species to environmental variations make it difficult to analyze communities, however we were able to better understand how different taxa react to environmental stressors and how communities shape themselves to withstand the tropical seasonality that has presented intense episodes with greater frequency. It is a fact that some species have leaf adaptations such as: increase in supraepidermal structures, epidermal thickening and parenchyma that allow greater regulation of water loss. But the increase in hydraulic safety due to less efficient and safer conducting vessels is almost unanimous. Although there is investment in xeromorphic attributes, we emphasize that these communities are at risk of major changes in their structure and composition due to the intensification of stressful climatic events.

MEMBROS DA BANCA:
Interno - 82329001 - BEN HUR MARIMON JUNIOR
Externo ao Programa - 253812001 - PEDRO VASCONCELOS EISENLOHR
Externo ao Programa - 117000004 - MARCO ANTONIO CAMILLO DE CARVALHO
Externo ao Programa - 96420004 - IVONE VIEIRA DA SILVA
Externo à Instituição - RAFAEL SILVA OLIVEIRA - UNICAMP
Externo à Instituição - CLAUDIA FRANCA BARROS - UFRJ
Externo à Instituição - Thaise Emilio Lopes de Sousa - UNICAMP