Efficiency of silvicultural treatments by girdling in the Jari Forest, Amapá

Abstract

The girdling is a silvicultural treatment applied in tropical forests in order to maintain or even increase the productivity of commercially exploited species to the next cutting cycle. In this research we analyzed effects of different levels of exploitation and silvicultural treatments on the dynamics of remaining forest in the Jari region/AP. The silvicultural treatment was improved in 1994 and applied to two types of thinning: systematic thinning, with intensities of original basal area reduction of 30% and 50% and selective thinning (with girdling slots and applying arboricida). In the application of treatment it were ringed on average 18.3 trees.ha-1, 2,1 m2 .ha-1 of basal area and 25.1 m3 .ha-1 of volume, total of 495 treated individuals (93 species). The amount of dead trees as a result of girdling had important variation between treatments. In general, the girdling with application of arboricida presented greater effect in relation to the species than to trees sizes. Species with furrowed trunks presented low mortality. Trees with less than 50 cm of diameter had a mortality rate of 61 to 90 percent. In superior diameter classes the mortality rate was similar, around 69 to 100 percent.