Ciclagem de nutrientes em Eucalyptus dunnii estabelecido no bioma Pampa

Abstract

The goal of this study was to evaluate aspects of nutrients cycling in Eucalyptus dunnii by monitoring a stand throughout a year. This took place in Alegrete town, Rio Grande do Sul state, South Brazil, in an area of Stora Enso S/A, starting when stand was 16.5 months old. It was evaluated monthly rainfall and litterfall. Rainwater inside the stand was collected in 12 throughfall collectors and 12 stemflow collectors. The bulk precipitation was evaluated by two rainwater collectors located outside the stand. Assessing the litterfall, 16 collectors with 0.5 m² area were installed for the evaluation of leaves and miscellaneous (bark, reproductive material and branches - diameter less than or equal to 5 mm) fractions, plus the installation of 16 areas to collect thick branches (diameter greater than 5 mm). Rainwater and litterfall collectors were disposed in 4 blocks. Precipitation and litterfall were assessed for quantity, concentration of nutrients and input of these nutrients. Rainfall was 1586 mm y-1, with 7% interception by the stand. Throughfall accounted for 98% of effective precipitation, and the remaining 2% was stemflow. The concentration of ions in bulk precipitation was low, consistent with the rural areas of non-industrialized regions. Higher inputs occurred after the interaction of bulk precipitation with the forest canopy. It was fell 4.1 Mg ha-1 y-1 litterfall, where leaves corresponded to 93%, 6% of miscellaneous and 1% of thick branches. The higher concentration of macro and micronutrients was in general found in leaves fraction. The nutrient input was higher to litterfall, except for the macronutrient S.