Estrutura, biomassa arbórea e composição florística de ilhas de mata da savana de Roraima, norte da Amazônia brasileira

• Ano de defesa: 2015
• Autor(a) principal: Almanza Jaramillo, Margarita Maria
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Roraima; Brasil; PRPPG - Pró-reitoria de Pesquisa e Pós-Graduação; PRONAT - Programa de Pós-Graduação em Recursos Naturais; UFRR
• Palavras-chave em Português: Amazônia; Savana; Carbono; Fragmentos florestais; Florestas sazonais; Aquecimento global; Amazon; Savanna; Carbon; Forest fragments; Seasonal forest; Global warming; CNPQ::CIENCIAS BIOLOGICAS
• Link de acesso: http://repositorio.ufrr.br:8080/jspui/handle/prefix/469

Forest ecosystems dispersed in matrices of Amazonian savannas have been suffering many types of anthropogenic impacts, in particular recurrent fire and selective logging. The carbon stock in the biomass of these systems and its contribution to mitigation of impacts generated by global warming are poorly known. The aim of this study was to estimate the living above ground biomass in anthropized forest islands (forest fragments) in the Savanna of Roraima, Northern Brazilian Amazon. Environmental factors were evaluated: the fragment dimension, forest structure (based on the position in the gradient: edge and interior) and the physical and chemical soil characteristics. A forest inventory was carried out in 12 forest fragments randomly chosen, taking into account three-dimensional categories (k = 3): large islands (20-60 ha), medium (10-20 ha) and small (< 10 ha). In each category were studied four fragments (n = 4) and in each fragment subplots were established (76 in total). All individuals with tree diameter at breast height (DBH) ≥ 10 cm were inventoried. The total height of each individual was estimated visually. Living above ground biomass was calculated for all individuals inventoried using indirect method (allometric equation). One thousand and eight seven (1087) individuals were observed of 112 tree species (including morphospecies) belonging to 29 botanical families. Pouteria surumuensis Baehni (Sapotaceae) was the most abundant species in all dimensional categories. Forest islands with larger dimensions have higher abundance for both late-growing and climax species, while smaller islands were dominated by pioneer species. The living above ground biomass did not differ between the edge and the interior of fragments regardless of dimension. However, the forest biomass of large (469.9 Mg ha-1), medium (357.1 Mg ha-1) and small (206.4 Mg ha-1) fragments differed significantly (ANOVA; Tukey0.05), indicating that larger fragments have higher living above ground biomass. The living above ground biomass did not present any relationship with the physical and chemical soil characteristics. The conclusion of this study is that living above ground biomass of forest islands in the Savanna of Roraima varies depending on the fragment size, but is independent of the position in the gradient (edge-interior), indicating no significant relationship with the structure or soil fertility.