Crescimento de espécies florestais submetidas à intervenções silviculturais em florestas secundárias, Bragança, Pará.

Abstract

The accelerated process of suppression and conversion of primary forests into different forms of land use has been a matter of global concern. The Northeast of Pará, particularly the Bragantina Zone, is an evident portrait of this process of environmental degradation, where its landscape is strongly marked by the presence of extensive areas with secondary vegetation, locally called capoeira, in various stages of development, originating mainly from the intensive practice of itinerant agriculture. In this scenario, the management of secondary forests through the application of silvicultural treatments, to the detriment of the practice of the slash-and-burn system, can be an alternative to guarantee food subsistence and complement the income of small rural producers, in addition to helping in the conservation and sustainable use of natural resources. The objective of this work is to evaluate the effects of two silvicultural interventions on the diametric growth of forest tree species of socioeconomic interest to smallholder farmers in the Bragantina region. The research was developed in the rural property of Mr. José Calixto, where two silvicultural interventions were carried out: Silvicultural Intervention I (first application of silvicultural treatments: carried out in 2000) and Silvicultural Intervention (reapplication of treatments: carried out in 2005). The treatments were defined as follows: TO plots (Witnesses: no silvicultural intervention) and T1 plots (with silvicultural intervention, The silvicultural interventions carried out consisted of ringing (thick trees), direct felling (thin trees) and cutting of lianas. The diameter growth of the treated group was higher when compared to the control group for both silvicultural interventions. The highest values of diametric increment, both for the group of treated individuals and witnesses, occur after the first silvicultural intervention. For silvicultural intervention I the species that presented higher values of annual periodic increment guianensis (1.58 cm year'), Byrsonima sp. (1.28 cm year'), Inga alba (0.96 cm year'), While for the second intervention (reapplication), the species Tapiriraguianensis, Stryphnodendron guianensis, Byrsonima sp. present higher values of diametric increment, respectively.