Dinâmica e biomassa aérea de um trecho de Floresta Ombrófila Mista Aluvial no município de Araucária, Paraná

Abstract

The study was carried out in one area located in Araucaria county, metropolitan region of Curitiba, Paraná State, Brazil, with approximate coordinates 25°35'12 '' S and 49°20'45 '' W, adjacent to Barigüi river, affluent of the right margin of Iguaçú river. The climate is Cfb (according to Köppen) and the vegetation classified as Alluvial Mixed Forest. An analysis of the vegetation dynamic was carried out using carried partial data of another study performed at this place and through the evaluation of 20 permanent plots in 2001 and 2003. Changes in floristic and phytosociologic composition, diameter distribution, growth (increment), entrance (recruitment) and mortality were evaluated. Simulation of the behavior of density and dominance variables was done through transition matrices. Another objective of this research was to assess the biomass of the arboreal vegetation (leaves, fruits and seeds, fine and thick branches, vascular and nonvascular epiphytes, wood and bark, of the regeneration (leaves, branches, wood and bark, of the herbaceous vegetation (aerial region and roots) and of the litter, having different sample areas for each one of these compartments. It was also possible to test and to adjust mathematical models capable of estimating the dry biomass. Small changes were verified in the floristic and phytosociologic composition of the community in the period between the measurements (2 years). A growth in basal area of 2.22 m2/ha (1.11 m2/ha/year) and, approximately 0.13 cm/stem/year in diameter was observed. These values are smaller than others found in different forest typology studies. The recruitment represented an increment in basal area of 0.20 m2/ha in the period, corresponding to an increase of 2.34% in the number of stems and 2.31% in the number of individuals. The percentage of mortality of the stems was 6.04% and of the individuals 3.27%, corresponding to 1.26 m2/ha in two years, primarily for Myrceugenia glaucescens and Schinus terebinthifolius species for the high indexes presented. For biomass evaluation a value around 195.5 t/ha was obtained, with the arboreal vegetation corresponding to 86.88% of this value, followed by the regeneration above 1.30m of height (10.27%), litter (2.23%), regeneration below 1.30m of height (0.39%) and herbaceous vegetation (0.23%). Mathematical models were adjusted for the estimate of the dry biomass of the arboreal component and its compartments. Good results were obtained for the estimate of the values of the tree as a whole and of the wood. The same did not happen for the thick branches, fine branches, leaves and bark compartments. Results of vegetation dynamic and biomass are scarce in Brazil and can be useful to subsidize programs of conservation and recuperation of gallery forests.