Serrapilheira e composição florística em sub-bosque de eucalipto pós-queimas prescritas com e sem retardantes de fogo de curta duração

Abstract

The objective was to evaluate and estimate the availability of combustible material (dry and live) in a planted Eucalyptus forest and to correlate the regeneration of herbaceous material in the understory at different environmental interfaces with the prescribed burning episodes, as well as to verify the effect of different concentrations of fire retardants and spray volumes applied in burns prescribed in previous experiments, in the regeneration of herbaceous plants. Collections of dead fuel (litter) and live (herbaceous) materials were performed with a quadrant of 1 m2, making 3 repetitions in each plot. All the dead material was sorted and classified into leaves, bark and branches. The plants were identified and quantified. Subsequently, the combustible materials (dead and herbaceous) were dried in an oven with forced air circulation, with a temperature of 65 ° C with a variation of ± 2 ° C, until constant weight. The dry mass was obtained with a thousandsimal analytical balance. When subjected to prescribed burns, the areas presented, at 36 months post-burning, a quantity and composition of litter similar to areas without burning (6.5 years). The supply of combustible material at 7.5 years of age was 22.21 and 13.30 Mg ha-1 for areas without burning and with 20 months post-burning, respectively. The leaves represented the largest fraction of the combustible material. The use of fire provides greater masses of regenerated herbaceous material in E. urograndis understory. With the increase in the post-firing period, new plant species were inserted in the understory, with the greatest abundance being those of the Poaceae family (grasses). When we evaluated the areas where fire retardants were applied, we concluded that there was no effect of the retardants in their different concentrations and volumes of syrup as for the richness and abundance of regenerated herbaceous vegetation species, however, the areas with burning showed less richness, being fire is primarily responsible for this difference.