Search

Relief is a soil formation factor that can modify the distribution of soil organic matter (SOM) fractions in a landscape. The objective of this study was to evaluate the effect of the relief on SOM fractions, considering their distribution in different topographic positions, segments, in two pedoforms (concave and convex) in areas covered with forest in the Atlantic Forest biome. The two pedoforms were selected in adjacent areas and divided into segments considering the topographic variation. The carbon and nitrogen origins were evaluated in the extract up to 100 cm of depth. Soil samples from the 0-5, 5-10, and 10-20 cm layers were collected for chemical characterization and fractioning (granulometric and chemical) of the SOM. The soil density in the 0- 5 and 5-10 cm layers was determined to calculated the carbon stocks. The isotopic composition showed predominance of 13C. The highest organic carbon and particulate carbon contents were found in the convex pedoform. The distribution of humic fractions showed that the larger part of the humidified carbon was in the humin fraction. The humin and fulvic acid fractions were higher in the convex pedoform. The carbon stocks were, in general, higher in the convex pedoform, decreasing as the soil depth increased; and nitrogen stocks presented no differences. The higher carbon and nitrogen contents were found in the convex pedoform and in the lower region of the concave pedoform. [ABSTRACT FROM AUTHOR]

Forest plays a fundamental role in the environmental balance, mainly in the regulation of the climate, main variable that interferes in the propagation of fire in a forest fire. Climate change is caused by astronomic, natural and anthropogenic factors, the latter being primarily responsible for the change in the fire regime. There is a projection that there will be climate changes over the next 100 years, which will result in an impact on forest ecosystems. Therefore, this study aimed to was to determine, by decade, the Forest Fire Risk Zone Mapping (FFRZM) for the state of Santa Catarina by considering the average of two scenarios for the increase of the temperature of the Earth until 2100 (1 °C for the best-case scenario and 2.2 ºC for the worstcase scenario) that were foreseen by the Intergovernmental Panel on Climate Change (IPCC) in 2013. For this purpose, eight variables classified according to fire risk and integrated in a weighting model were used. The results showed that, for both scenarios, there will be an increase of 11.48% in the best-case scenario and 10.83% in the worst-case scenario in the extreme risk class from 2010 to 2100. For the low risk one, we estimate that there will be an increase of 8.13% in the best-case scenario and 11.62% in the worst-case scenario. The study reveals that if there is an increase in the temperature of the Earth, there may be an increase in the number of forest fire occurrences in the state of Santa Catarina for both scenarios. Thus, it is necessary a greater action on the prevention and combat in the areas defined as extreme risk. [ABSTRACT FROM AUTHOR]

Variations in the growth site of trees have influence on the internal structure of the trunk. Considering this fact, this study investigated influence of the characteristics of the growth site on wood specific gravity of two clones of Eucalyptus urophyllax Eucalyptus grandis, approximately six years old, growing in different altitudes and topographies. Furthemore, two methods of sampling of the wood specific gravity were studied, for comparison purpose. Results showed that wood specific gravity underwent variations between growth conditions andtrends in wood specific gravity variations, compared between growth conditions, were the same regardless of the clone. With relation to sampling method, the wedge was more appropriate for determination of wood specific gravity, in order to extrapolate the disc density. These results provide tools to forestry companies about consolidation of genetic material and its behavior in different growth conditions, to attend wood quality requirements. [ABSTRACT FROM AUTHOR]