Dinâmica das populações de três espécies madeireiras ameaçadas de extinção na Amazônia Oriental

Abstract

The management of endangered species should be used as a conservation strategy, and it is essential to know the behavior of these species in relation to the logging and the recovery rate of their stock within the cutting cycle established for the forest. Thus, we evaluated the dynamics of the populations of Hymenaea parvifolia Huber, Hymenolobium excelsum Ducke and Vouacapoua americana Aubl., classified as endangered by the International Union for Conservation of Nature (IUCN). The research was divided in three parts that contemplate its specific objectives. In the first part populations dynamics of H. parvifolia, H. excelsum and V. americana were evaluated the considering the horizontal structure, the rates of ingrowth and mortality and the spatial distribution of individuals. The second part evaluated the basal area, volume and diameter distribution of the species H. parvifolia and H. excelsum; and in the third part the dynamics of the natural regeneration of the populations of H. parvifolia, H. excelsum and V. americana was evaluated considering the abundance of their populations. The research was carried out in three experimental areas administered by Embrapa Amazônia Oriental, two of which were located in the Tapajós National Forest (Km 114 and Km 67 of BR 163) and one at the Embrapa Experimental Field in the municipality of Moju. Changes caused by reduced impact logging on the structure, ingrowth, and mortality of Individuals of the H. parvifolia, H. excelsum and V. americana were not significant during the monitoring period. The period of 30 years after logging was not sufficient for H. parvifolia to recover the number of trees, basal area and volume existing before harvest, considering individuals with DBH ≥ 45 cm. The high harvest intensity did not allow H. excelsum to recover the number of trees with DBH ≥ 45 cm that existed before the logging in the period of 30 years, but the species has growing stock that can guarantee its conservation and future logging. The absence of individuals in the natural regeneration of H. parvifolia and H. excelsum in the unlogged forest and the low number of individuals in the managed forest indicated how difficult is to these species to regenerate and get established in the forest, and this would lead to their extinction in the area. Natural regeneration of V. americana is abundant, guaranteeing its constant presence in the area, with no risk of extinction. It is recommended the application of silvicultural treatments directed to stimulate the natural regeneration in the areas of Km 67 and Km 114. The planting and the conduction of the natural regeneration are recommended to guarantee the permanence of the population of the species in the area of management.