Navegando por Assunto "Fazenda Tanguro - MT"

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Acesso aberto (Open Access)
Efeitos do fogo recorrente na serrapilheira: consequências para artrópodes, decomposição e mineralização de carbono e nitrogênio em uma floresta de transição da Amazônia
(Universidade Federal do Pará, 2008) SILVEIRA, Juliana Miranda da; MOUTINHO, Paulo Roberto de Souza; http://lattes.cnpq.br/7277077476036269
Arthropods play an important role in ecosystem functioning, participating in nutrient cycling, decomposition and the breaking up and mixing of the leaf litter. Forest fires are increasing across the Amazon basin, and destroy the litter layer and kill the invertebrates that live within it. The objective of this thesis is to investigate how recurrent fires affect these processes, investigating the abundance and density of leaf-litter arthropods and the rate of decomposition of organic material and the mineralization of C and N, in a transitional Amazonian forest in the municipality of Querencia in the state of Mato Grosso, Brazil. The study was conducted in 50 ha of primary forest (500 x 1000 m) that was experimentally burned every year from 2004, and an unburned primary forest control of the same size. The arthropods were collected in 40 pitfall traps and 40 funnel Berlese traps, located randomly. The collections were undertaken in February, April (wet season), June, and August (dry season) of 2007, after the third experimental burning. The arthropods were identified to the level of Order, and the ants were identified to the level of Genera. The decomposition study was undertaken using 480 litter bags, randomly distributed with 240 in each plot, 4 months after the last burns. The litter bags were constructed with 2 mm nylon mesh (fine mesh), and 50% of them had 1 cm² holes cut in their sides (coarse mesh). 10g of dry leaves were placed in each litter bag, and 30 bags were collected from each plot every 2 months, equalling 2 collections in the wet season and 2 in the dry season. The litter bags were dried in an oven, and litter was weighted again to calculate decomposition. The difference between inicial and final weight showed the decomposition rate. Ten litter bags were selected randomly from every collection, mesh size, and plot, and subjected to a C and N analysis. The arthropods demonstrated strong seasonal differences. Springtails were less abundant and ants were more abundant in the dry season. Along with the seasonal effects, arthropods had diverse effects to the recurrent fires: Orthoptera were always more abundant in the burned plots in all post-fire samples when compared to controle plot. In general, macro-predators (ants, beetles, and others) were more abundant in the burned forest, while the ecosystem engineers and decomposers (cockroaches, Acaridae, and others) were less abundant in the burned forest, when compared to control plot. Ants were more diverse in the dry season, and also showed strong seasonal differences in composition. There was also a marked difference in ant diversity between the two plots, and fires favoured generalists ants. The decomposition rate in the burned forest were lower than in the control, and the fine mesh litter bags had a lower rate of decomposition than those with holes cut in their sides (coarse mesh). The level of C and N was also different between the plots, and the C/N ratio (indicating microbial activity) was stable over time in all post-fire collections, while the C/N ratio in the control plot declined gradually during the 4 collections. These results indicate that fire modifies the leaf-litter fauna, affecting the abundance and composition of various taxonomic groups. The fine mesh litter bags indicate that the exclusion of macroarthropods reduces the rate of organic matter decomposition and that microarthropods are more affected by fires. Fire also reduces the mineralization of C e N as C/N was stable in burned plot. Overall, this study shows that recurrent fires have strongly effects on leaf-litter fauna and nutrient cycling in Amazonian transitional forests.
Acesso aberto (Open Access)
Influência dos fatores ambientais na diversidade e modos reprodutivos de anuros em área de floresta de transição, Mato Grosso
(Universidade Federal do Pará, 2010) BITAR, Youszef Oliveira da Cunha; COSTA, Maria Cristina dos Santos; http://lattes.cnpq.br/1580962389416378