Análise dos aspectos socioeconômicos, fito-demográficos, genéticos e físico-químicos da extração do óleo-resina de Copaifera reticulata em duas comunidades da Flona do Tapajós, Pará

Abstract

Copaibas are trees that are native to tropics, with nine species found in Brazilian Amazonia. Copaiba trees produce an oil-resin that is found in secretory channels located in the trunks. Copaifera reticulata is the predominant species in the Tapajós National Forest. The socioeconomic aspects of the communities of Pedreira and São Domingos, who are authorized to collect copaiba, and the phytodemographic, genetic and physical-chemical aspects of the copaiba populations available to these communities were analyzed, with the objective of subsidizing future actions of copaiba management in the Tapajós Flona. In the socioeconomic study, semi-structured interviews with the communities extractors elucidated the current local situation with respect to the extraction of copaiba. In the phytodemographic study, the species was identified, the density of potentially productive individuals was quantified, and these were mapped. Microsatellite markers developed by Embrapa Genetic Resources and Biotechnology were used for the genetic analyses. The physical-chemical parameters used were density and viscosity of the oil-resin, as these are associated with potential uses and for the chemical study it was the refraction index, acidity, saponificacion and éster. The management of copaiba is technologically simple, but the extractors identified numerous difficulties, including less advantage in the sale of the oil-resin than formerly, showing that the situation in the past that stimulated them is very different from the current situation, especially in the commercialization process. The density of productive trees in the collection area of Km 67 was 5,5 and of Km 72 was 6,2, with 200 adult individuals geo-referenced. The largest number of productive trees was in the diameter class 51-70 cm, totaling 88 trees, and the largest diameter found was 120 cm. To C. reticulata it presents an oil-resin with viscosity 9 (mPa.s) very variable and it lowers acidity (mg of KOH/g), which could serve as a basis for oil-resin differentiation. With the six microsatellite loci that transferred, 78 alleles were observed. The genetic diversity (He) varied from 0.59 to 0.85 per locus, considered high for Neotropical tree species; however, the observed heterozygosity was smaller than the expected heterozygosity by the Hardy-Weinberg equilibrium in the collection areas, demonstrating a reasonable level of inbreeding (f = 0.375 to 0.419), probably due to a clumped distribution. The analysis with Structure did not identify two populations based on the collection areas, but two genetic groupings based on different combinations of alleles. Most of the genetic variation was found within the collection areas (97%), with weak genetic differentiation among the areas (Fst = 0.030). A little less genetic variation it was found within the genetic groups (93%), with a corresponding increase in divergence (Fst = 0.070). The noncorrespondence between collection areas and genetic groupings could be due to unknown historical events, but, combined with the high genetic diversity founds, suggests that the current levels of inbreeding won't be a problem for a management plan, although the isolation of the Tapajós Flona in the future could contribute to elevate inbreeding to worrying levels. The information presented here will serve as a baseline for future comparison, guiding improvements in the management plan.