Abstract
The forest monitoring after exploration activities is an important tool for forest management, helping to plan the use of forest resources. This research aimed to evaluate the impacts on tree vegetation after one year of the end of forest harvesting in concession area in the Jamari National Forest, RO. The vegetation was evaluated before and after the exploitation in an Annual Production Unit (APU) with cutting rate of 14.14 m³ ha-1. In total, seven permanent plots of 0.5 ha were divided and randomly distributed, where all individuals with diameter at breast height (DBH) ≥ 10 cm were evaluated. Impact evaluation was based on two criteria, the diversity and structure of vegetation (phytosociological, parametric, diametric, and internal). There was a reduction of 2% in plant density and loss of two species. The volumetric supply decreased in the classes above 80 cm of DBH and the diametric structure maintained the largest supply of plants in the lower classes. The exploration activities collaborated in 3.57% to increase the mortality rate, besides causing slight and severe damages in 15 ind.ha-1. The quality of the stem was predominantly straight (82.36%). The damage observed is within the expected limits for areas with low cut rates and subjected to reduced impact exploration techniques. We suggest the continuous monitoring in the medium- and long- term in order to describe the patterns of regeneration and growth of species, mainly logging, projecting the future supply of cutting.Keywords: Management in natural forests; Forest dynamics; Forest concession.
Highlights
The main causes of forest cover loss in the Amazon over the years have been associated, mainly with the opening of federal roads, implementation of settlements, hydroelectric and mining projects, illegal exploitation of high commercial value species, and opening of areas for agricultural activities (VALERIANO et al, 2012).the Brazilian government has implemented conservation policies in order to promote the use and protection of natural resources, such as the National System of Nature Conservation Unit (SNUC), which establishes criteria and regulations for creation, implementation, and management of conservation units and the Public Forest Management Regulation, Law No 11,284/2006, which provides for a management model in whichFLORESTA, Curitiba, PR, v. 50, n. 4, p. 1778 - 1787, out/dez 2020
One year after the end of the exploitation activities, a 2% reduction in the total density of individuals with diameter at breast height (DBH) ≥ 10 cm was observed, from 464.28 ind.ha-1 to 454.86 ind.ha-1 and the disappearance of two genera and two species, the number of families was the same (Table 1)
When analyzing the average values of absolute density (AD), absolute dominance (ADo) and estimated volume before and after exploration, it was observed that the differences between the means were not significant (p > 0.05), note that the total forest supply before and after the exploitation were similar (Table 1)
Summary
The main causes of forest cover loss in the Amazon over the years have been associated, mainly with the opening of federal roads, implementation of settlements, hydroelectric and mining projects, illegal exploitation of high commercial value species, and opening of areas for agricultural activities (VALERIANO et al, 2012).the Brazilian government has implemented conservation policies in order to promote the use and protection of natural resources, such as the National System of Nature Conservation Unit (SNUC), which establishes criteria and regulations for creation, implementation, and management of conservation units and the Public Forest Management Regulation, Law No 11,284/2006, which provides for a management model in whichFLORESTA, Curitiba, PR, v. 50, n. 4, p. 1778 - 1787, out/dez 2020. 65680 the government can grant companies and communities the right to manage Conservation Units (CU) for sustainable use, exploiting timber and non-timber resources (BRASIL, 2006). In this scenario, Rondônia was the first Brazilian state to bid and to approve the concession of forests by the Brazilian Forest Service (SFB) in 2007 in the Jamari National Forest. National Forests are conservation units of sustainable use, with forest cover of predominantly native species and they have as basic objective the multiple use of forest resources and scientific research, with emphasis on methods for sustainable exploitation of native forests (BRASIL, 2000)
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