Determinação do potencial silvicultural de espécies do gênero Cecropia na flona do Tapajós – PA.

Abstract

Classified as pioneers in the process of forest succession, the species of the genus Cecropia, belonging to the family Urticaceae, popularly known as embaúba, have the characteristics of rapidly occupying open clearings naturally, by forest exploitation or secondary formations from abandoned agricultural activities. Parameters such as rapid growth, broad spatial distribution and high abundance associated with the favorable wood technological properties for use in industry place the genus in the forefront of the need to introduce new species to the market in order to compose future crops. Thus, the objective of this work was to determine the silvicultural potential of the species of the genus Cecropia through the horizontal structure, population dynamics and the characterization of the post-harvest forest potential. The experiment is located in Tapajós FLONA, municipality of Belterra-PA, where in 1979 the forest exploitation was carried out. In 1981, 36 permanent plots were installed at random, and all individuals with DBH ≥ 5 cm were inventoried. The measurements were carried out in nine consecutive seasons (1981, 1982, 1983, 1985, 1987, 1992, 1997, 2007 and 2012) in 33 years after forest exploitation. Inspection plots were also installed near the experimental area. Two species of the genus Cecropia distachya and Cecropia sciadophylla were identified in the area. A considerable increase in density was observed, reaching a maximum in four years after the exploration (82.3 trees.ha-1) and subsequent decrease until reaching, after 28 years, values similar to the unexplored area. In terms of dominance and volume, Cecropia presented a significant increase at 13 years post-harvest (1.7 m².ha-1, 15.6 m³.ha-1), with a maximum yield slightly higher in volume at 18 years (16.4 m³.ha -1), and from this moment a rapid decline. Admission rates were much higher than mortality rates 3 years after the exploration. From the third period, 6 years after exploration (1985), there was a negative balance until the end of the monitoring. Cecropia sp. Showed high increases soon after the forest exploitation, and C. sciadophylla showed greater growth considering all period (1981-2012). It is concluded that the species of the genus Cecropia present a high silvicultural potential for the production of wood after forest exploitation in a shorter time than the cutting cycle established in the legislation, which is 35 years old, which suggests a different management because they present dynamics of short term.