BIOMASSA, CARBONO E POTENCIAL ENERGÉTICO EM UM PLANTIO MISTO DE Pinus taeda L. E Pinus elliottii Engelm.

Abstract

The present study aimed to analyze biomass and carbon production in a mixed plantation of Pinus taeda and Pinus elliottii, adjust models and evaluate the effect of the sample intensity on the biomass estimation when compared to the complete enumeration. In addition, were determined energy potential of the species. The stand, which total area is 43.579 ha, had the complete enumeration of individuals (forest census), at the age of 16, which is located in the municipality of Bituruna, state of Paraná, Brazil. Based on the diameter distribution generated in the forest census, 60 trees were randomly selected, 30 of each species, and the biomass and carbon were determined by direct destructive method. Biomass was also evaluated using the stratified tree technique by diameter classes in the complete enumeration. In the modeling, three approaches were tested to estimate the aerial biomass in the mixed planting: independent adjustment, simultaneous adjustment and the nearest neighbor technique. The best equations were applied to the trees from stand to obtain parametric values of aerial biomass. In the sampling, the fixed area method was used, with the systematic sampling process, circular plot of 600 m² and 1, 2 and 5% sample fractions of the population, were evaluated to estimate the biomass with the same equation. The parametric and estimated biomass were compared based on the sample error and real error. Finally, the energy potential of the species were evaluated in order to identify which specie presented the best characteristics. Determination of biomass by the direct method revealed heterogeneity in aerial biomass production among the species, Pinus taeda had higher biomass mean in relation to Pinus elliottii. However, the difference between species was not significant. Mixed plantation of Pinus spp. produced 171.5 t ha-1 of aerial biomass, and stored 77.0 t ha-1 of carbon. Among the approaches used to estimate the aerial biomass of the mixed plantation, the simultaneous adjustment was similar to the independent adjustment. However, besides the quality, the simultaneous modeling has the advantage that when adding the biomass of the components, the result is compatible with the total biomass. The technique of the nearest neighbor did not present satisfactory results. From the simultaneous adjustment, the biomass production in the mixed plantation revealed that the sample fraction of 5% was the one that most approached the parametric values. Likewise, the stratified tree technique revealed that the biomass in the sample fraction of 5% was the one that best characterized the population, with a real error -3.1%. However, the technique was not recommended in biomass estimates by species because the real error is greater than 10%. For biomass energy, Pinus elliottii showed to have the best characteristics in relation to Pinus taeda.