Abstract
This study sought to classify the productivity of a representative area of tropical forest, as well as to analyze the relationship between the structural variability of pioneer species and the yield of three management regimes. The study area is located at the Tropical Forestry Experimental Station belonging to INPA (National Institute for Amazon Research), approximately 90 km from downtown Manaus, in the State of Amazonas, Brazil. Data were collected from twelve 1 ha sample plots. Diameter was measured annually for all individuals with DBH 10 cm between the years 1990 and 2008. Pioneer species served as the basis for calculating the Diameter Variability Index VI% over time. Three classes of variability were established according to the guide curve technique used for site classification by the dominant height. Biological and probabilistic functions were used to model VI% as a function of time of exploitation, as well as the volumetric yield over time as a function of VI%. There is an inverse relationship between VI% and yield, which allows classification of site yield and conception of global yield models to which present good statistics of precision and adjustment, allowing the prediction of productivity and their dynamics throughout the time.
Highlights
The dynamics of yield in primary, uneven aged and heterogeneous forests are determined by the occurrence of n events that alter the structure and number of species present in the environment
Using the adjusted Log Normal function we identified the year of least variability in diameter of pioneer species for all treatments and their replicates, which occurs in the 17th year after logging, and thereafter there is a gradual increase in the variability in diameter of pioneer species (Figure 1)
The increase in the number of pioneer species logged in different treatments alters the structural variability of these species in each site
Summary
The dynamics of yield in primary, uneven aged and heterogeneous forests are determined by the occurrence of n events that alter the structure and number of species present in the environment. By observing the horizontal structure of a disturbed forest, it is possible to observe the increased establishment of pioneer species in a forest by natural succession alters the variability in diameter of the forest population, because of the increased number of small individuals (FRANKIN et al, 2002). Their presence modifies the physical attributes of the forest, as well as the ecological group to which they belong (SPIES; FRANKLIN, 1989). This change of variability in diameter can be measured, and their degree of homogeneity is inversely related to the productive capacity of the site (NASCIMENTO, 2012)
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