Estimate of the diameter distribution in Mixed Ombrophylous Forest fragment with the Meyer's function

Abstract

Evaluate the diameter distribution of a fragment of Ombrophyllous Mixed Forest, located in São Francisco de Paula, Rio Grande do Sul. The data was collected in 10 permanent sampling units of 1ha each, established in the São Francisco de Paula's National Forest, RS, Brazil.For analysis of the diameter structure was considered the frequency of diameters in successive classes of range of 10cm, and the intervals diameters ranging from 9.5 to 149.5 cm. For data processing was used SADEF software. The frequencies observed by diameter class were divided into plots and adjusted as a function of the center class through of the Meyer`s equation, where was obtained value of 1.63 for the Liocourt quotient. We observed a total of 803 trees per hectare, distributed in 107 species belonging to 41 families. The most abundant species was the Araucaria angustifolia, with 97.1 individuals per hectare. The number of trees per hectare adjusted by the Meyer`s equation was 467.85, being lower than the observed, but basal area observed (46.18 m 2 ha -1 ) was lower than the adjusted (47.74 m 2 ha -1 ), with a deficit of 1.56 m 2 ha -1 . Through analysis of data from distributions diameter, it was verified that the ratio of Liocourt showed a range between 1 and 3.078. The data analysis indicates that the forest is still not in equilibrium, this disequilibrium in the frequencies of the diameter class occurs mainly in the classes with largest DBH, which may have been caused by selective extraction of some species.

Optimal selective logging regime and log landing location models: a case study in the Amazon forest

“…After determining the species suitable to be harvested we quantified the Liocourt's constant "q" value. This relationship generates a geometric series from the diameter distribution, defined as the ratio of number of trees in a given diameter class and the number of trees in the next diameter class (Watzlawick et al 2013). The constant value "q" was derived from the Meyer model (equation 1), where: Y i = number of trees per hectare from the class i; β 0 , β 1 = parameters to be estimated and x i = central value of diameter class i.…”

POPULATION STRUCTURE OF Araucaria angustifolia IN THE IGUAÇU NATIONAL PARK

“…However, they did not present characters of a balanced forest, because they did not show a constant reduction rate in number of plants following diameter increase (MEYER, 1952 The reduced number of trees in the core site between classes from 60 to 70 cm diameter, and in the edge site starting from 70 cm diameter, may indicate that there have been a previous disturbance (PINHEIRO;MONTEIRO, 2009). Lack of individuals in the bigger diameter classes in the forest edge site corroborates the conservation status, being characterized as a less conserved in the intermediate stages of succession caused by proximity to the conservation area limits and possible timbering in the past (WATZLAWICK et al, 2013). In the core site, lack of individuals in the classes from 60 to 70 cm also suggests alteration in the population structure, as suggested by Felifili et al (1988), where in most of the cases discontinuities, flattening and even total absence of trees are observed, in some of the diametric classes.…”