Respostas Ecofisiológicas e Metabólicas de B. Excelsa Submetida a Desbaste e a Fertilização Nitrogenada em Plantio Misto na Amazônia Central

Abstract

The ecophysiological responses of native forest species to silvicultural interventions should be studied with a focus on understanding physiological processes such as the photosynthetic performance and adjustment of the metabolism of trees. By analyzing the mechanisms that justify plant growth and its acclimatization to site variations, it is possible to improve forest management techniques to achieve greater productivity in commercial plantations. This dissertation aims to gather information on how silvicultural interventions can help increase the productive capacity of Bertholletia excelsa in different planting systems, focusing on the ecophysiological and metabolic responses of the species in a mixed planting with Tachigali vulgaris. Thus, the first chapter deals with a literature review on the main information on the functional responses of the Brazil nut tree to silvicultural interventions in different planting systems in the Amazon region. The second and third chapters were based on an experiment carried out at the Experimental Station of Caldeirão - Iranduba, Amazonas, in which growth rates, efficiency in the use of water and nutrients, morphology, photochemical performance, and carbon and nitrogen metabolism were analyzed. B. excelsa has high plasticity to contrasting light environments and adapts to low nutrient content in the soil. However, the sudden change in the light environment caused by the practice of thinning can result in stressful situations that affect the performance of individuals and, consequently, their productivity in forest plantations. Our results suggest that the application of fertilization, mainly nitrogen, followed by thinning can alleviate the light stress caused by thinning and cause an increase in the growth rates of B. excelsa.