Dinâmica da regeneração natural de espécies da família Lauraceae em floresta após exploração madeireira, Moju - PA.

Abstract

The study of forest dynamics is a reestablishment of the observation instrument of an ecosystem over time and involves, within the community, several processes between its components regulation processes, such as the succession, mortality, recruitment, growth, regeneration and relations between different populations influenced by the environment. This study tried to generate more information about the dynamics of natural regeneration of a group of species of the family Lauraceae, which are of great economic importance and ecological and with that determine the best way to leverage the capabilities of forests, seeking to reduce the damage to the environment and ensure greater profitability. For the data collection was performed a monitoring in 200ha in the experimental area of Embrapa in the municipality of Moju, after a exploration florestry. Were selected nine treefall gaps caused by the exploration and installed lanes of 10m x 50m, starting at broidered the clearing for inside of forest in the direction North, South, East and West. Each strip was divided into square plots of 10m of hand numbered 1 to 5, where were measured the individuals with (DBH) ≥ 10 cm within plots 1, 3 and 5 were installed sub-plots of 2m x 2m, covering the individuals with total height (Ht) ≥ 10cm and Diameter at breast height (DBH) < 5cm, considered as natural regeneration. In the center of the gap was installed also a sub-plots of 2m x 2m in hand for the purpose of comparison. The measurements occurred from March 1998 finishing the first step in 2001; in 2007 were carried out two further measurements, and a last measurement in the year of 2010, totaling sixteen measurements in a period of 12 years of observation, to evaluate the natural regeneration rate, ingrowth and mortality of the species. The results for the TR%, I%, and M% showed that there was a decrease in the density of the population of the species, in four directions cardinals, the regeneration rates were positive at beginning of the study and negative in the end, except in the center of clearings where the rates were zero in the second period, showing at a given moment the balance between ingrowth and mortality.In relation to the sizes of treefall gaps, regeneration rates if showed positive in the gaps small and medium and negative or zero in large gaps, this behavior of species typically intolerant to shade, because hardly survive the lack of sunlight. Among the studied species, Nectandra amazonicum Ness and Ocotea guianensis Aubl. presented better development in treefall gaps in the initial periods of study, however with higher mortality at the end of the period of 12 years, which proves the intolerance in the shade of the species, because the same need fully to light to survive.