O destino dos remanescentes de vegetação no maior hotspot da Amazônia Meridional : uma análise de 33 anos de uso da terra na Bacia do Rio Tapajós

• Ano de defesa: 2022
• Autor(a) principal: Borges, Guilherme Augusto Nogueira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Mato Grosso; Brasil; Instituto de Biociências (IB); UFMT CUC - Cuiabá; Programa de Pós-Graduação em Biodiversidade e Biotecnologia - Rede BIONORTE – PPG-BIONORTE
• Palavras-chave em Português: Análises espaço-temporal; Ecótono Cerrado-Amazônia; Remanescentes de florestas e savanas; Perda de habitats; Interioridade; Nova métrica de paisagem; CNPQ::CIENCIAS BIOLOGICAS; Space-time analyses; Cerrado-Amazon ecotone; Remains of forests and savannahs; Loss of habitats; Interiority; New landscape metrics
• Link de acesso: http://ri.ufmt.br/handle/1/5702

In the present study, the dynamics of fragmentation of native vegetation cover (NVC) from 1985 to 2018 in the most threatened basin of the Rio Tapajós (BRT), a basin of the Amazon River, was evaluated. The study analyzes how land use pressures negatively impacted the remnants of the agricultural matrix and the biodiversity of local biotas, with the aim of creating a database for comparative studies. A sampling grid with hexagons of 50,000 hectares each was elaborated, compartmentalized as follows: for the entire area of the basin, a grid of 1255 hexagons was used in the analyses; 965 hexagons in the northern portion of the basin (Amazon biome) and 290 hexagons in the southern portion of the basin (Cerrado biome). Six landscape ecology metrics were applied to the grids: number, size, edge, isolation, remnants and interiority (unprecedented in landscape studies). The hexagons created made up the analytical units in the study of isolation and loss of habitats between the remaining forests (Fo) and vavannas (Sa) in the three defined Core Areas. The results showed that the fragmentation dynamics in the BRT was not a single isolated event in the three analyzed compartments, with different clusters in the studied portions. The number of remnants grew exponentially in the landscape, in the first 20 years of the study (1985-2005), their areas lost half their original sizes in both portions of the basin. Regardless of size or typology, the edge effect was high in the small and large remnants (Fo = 15% and Sa = 20%), with the largest and increasing isolation in the northern portion of the basin in 20 years (1985-2005). The insulation class 100 to 1000 meters increased by 31% for the remnants of Fo, while those of Sa increased by only 11% in the southern portion of the basin. The total losses of remnants (Fo+Sa) in the northern portion were 38% and 41% in the southern portion. Thus, the analyzes show that 60% of the Planalto area of the basin was converted into planted pastures and annual crops. If the same rates of deforestation and fragmentation remain at the current level, the BRT prognosis for 2040 will be for an increase in fragmentation and a reduction in the areas of total remaining savannah vegetation.