Ingresso e mortalidade do estrato arbóreo em floresta manejada na Flona do Tapajós

Abstract

The context of conservation of the Amazon rainforest requires forest management and the maintenance of natural resources for future generations. The objective of this work was to study the mortality and entry rates of new individuals in the tree extract in forest managed for wood production. The study was carried out in a community forest management area in the Tapajós National Forest (Tapajós FLONA) at KM 72 of BR 163, Belterra-PA. Seven permanent plots of 50 m x 50 m were used, randomly distributed in an area of 700 ha. All trees with PAC (circumference at breast height) greater than or equal to 32.0 cm (DBH ≥ 10cm) were identified and measured during three measurements. Data were analyzed in the Tropical Forest Monitoring program (MFT) and mortality and income calculations verified in two periods (2009 to 2011 before logging and two years after this activity) and the second from 2011 to 2015 (between two and six years after exploitation). In the first follow-up period (2009-2011), the mortality rate was higher than that of 27.4 individuals.ha-1.year and 11.1 tickets.ha-1.year-1, in percentages 12. , 3% and 5%, respectively, of the initial number of trees, observed in 2009. In the second period these rates were inverted, being 10.7 individuals.ha-1.year-1, 12.5 tickets.ha-1.year- 1 and percentages of 10.1% and 11.9% respectively. Mortality from logging was higher in the period immediately after logging, with approximately 19.43 individuals.ha-1year-1 (71%), natural mortality was 6.86 individuals.ha-1year-1 (25%) ), and harvested trees contributed 1.14 / ha / year (4%), in the second period, the situation was reversed, with natural mortality around 9.71 individuals.ha-1year-1 (93%) while that caused by exploitation approaches 0.72 individualsha-1year-1 (7%). The highest mortality rates were observed in the smallest diameter classes. In the period 2009-2011 approximately 42% of deaths were concentrated in the first class of diameter (10 - 19.9 cm), for the second period (2011-2015) natural mortality stood out with 78% distributed in the first and second DBH classes (10-30cm). The highest mortality rates were observed for Ingá Xixica (Inga sclerofilla) and Ucuubarana (Iryanthera sagotiana), in percentage terms 15.3% and 12.9%, respectively, of the total mortality observed over the entire follow-up period, while for In addition, white Embaúba (Cecropia distachya) and Uruá (Cordia exaltata) stood out with 19% and 15.5%, respectively. For the ecological groups the group of sciophytes had higher mortality rates as well as admission rates than the Heliophiles, 63% and 37%, respectively. Thus, the forest initially damaged by exploitation begins to show its resilience in the course of measurements by increasing the number of tickets.