Generatation of models for the management of Araucaria forests in southern Brazil using morphometric relationships with density is still scarce. Changes in the dynamics of the shape and size of trees in the forest indicate the need to regulate the density of trees (silvicultural intervention) or self-adjustment of the species to shape structure, living space, competition, growth rate and resource use. Trees with larger crowns show higher growth rate and their size inform the vital space of growth and support management density of the forest. This information is important to support forest management and can be used to build individual tree growth models. Management models built based on the relationship between forest density and morphometric variables are powerful tools to achieve sustainable yield. Thus, the purpose of this study was to adjust equations to express the diameter, the shape of the crown in function of morphometric/dendrometric variables and to relate the dynamics of the changes in crown surface area and the number of trees per hectare with the diameter and crown surface area. Morphometric and dendrometric data were measured from individual trees in 25 permanent plots located in 84 hectares of a natural forest with predominance of Araucaria angustifolia (Bertol.) Kuntze species. The diameter at breast height, total height, crown insertion height and four crown radius were measured, including 330 trees. The data were subjected to Pearson correlation analysis and regression conditioners (normality and homogeneity of variance). All the equations proposed in the objectives were generated using generalized linear models (GLM) techniques, which showed accuracy and precision with low values of deviation and Akaike criterion. The results showed that there is interaction between crown shape, density and diameter, indicated by Pearson correlation higher than 0.9. The interactions of crown and density variables identified requirements of silvicultural interventions and the period to perform these activities according to the mean diameter of the forest or to a desired diameter. This is important information for the conservation of the Araucaria Forest structure.

The sustainable management of mixed ombrophilous forest is an effective way to perpetuate the survival of Brazilian pine and to generate environmental, economic and social benefits. So, this study aimed to describe the dynamics of the diametric distribution to propose a management intervention using the Liocourt model for a natural forest of Araucaria angustifolia within 84 ha of forests located in Lages, SC, Brazil. A total of 25 permanent plots of 400 m² were evaluated in two periods (periodic inventory performed in 2012 and 2016). The diameters at the breast height and the total height of all Brazilian pine individuals with diameter from 10 centimeters were measured. For the calculation of the quotient "q" the individuals were divided into diametric classes with intervals of 5 cm. The cutting intensity and the cutting rate for the cutting cycles of 20, 25 and 30 years were also calculated. This Brazilian pine forest presented J-inverted distribution curve and the value for the quotient "q" was 1.32. The cutting rates were 44.89 m³. ha-1 , 63.64 m³. ha-1 and 86.52 m³. ha-1 for the cutting cycles of 20, 25 and 30 years, respectively. In conclusion, this work demonstrated a forest structure that allows the forest management activity and the use of Liocourt method as a tool to elaborate forest management plans and to improve the forest interventions in Brazilian pine forests.

Resumo: O presente trabalho teve como objetivo caracterizar a composição florística e a estrutura fitossociológica de um fragmento de floresta estacional subtropical localizado no interior do município de Lavras do Sul, Rio Grande do Sul. Para a amostragem, foram demarcadas na área quatro faixas, subdivididas em parcelas de 10 × 10 m, totalizando 0,27 ha. Em cada unidade amostral foi realizada a identificação botânica de todos os indivíduos com circunferência à altura do peito (CAP) maior ou igual a 31,4 cm, bem como a mensuração da altura total e do CAP, sendo determinados os parâmetros fitossociológicos da estrutura horizontal do fragmento, além da distribuição dos indivíduos em classes de diâmetro e de altura. Foram amostrados 216 indivíduos arbóreo-arbustivos na área (800 ind.ha -1 ), distribuídos em 17 espécies e 11 famílias botânicas, sendo as espécies mais importantes Lithraea molleoides, Blepharocalyx salicifolius, Scutia buxifolia, Ocotea pulchella e Styrax leprosus. Das espécies, 54% apresentaram padrão de distribuição agrupado, destacando-se Celtis iguanaea e Scutia buxifolia, e 46% exibiram padrão de distribuição com tendência ao agrupamento. Ocorreu maior concentração de indivíduos nas classes de altura intermediária e nas menores classes de diâmetro, podendo-se inferir que o fragmento se encontra em estágio secundário de sucessão.

The form of distribution found for the dendro/morphometric variables determines the structure, stability, productivity of forest stands, being a tool to propose silvicultural interventions, management, conservation of species, and dynamics of this environment. Thus, this study evaluates, using probability density functions (pdf), the form of distribution of these variables for araucaria in five sites in southern Brazil, aiming to establish the dynamics and identify the existence of a standard—or the lack thereof—to propose the need for silvicultural interventions to conserve the species and the future forest structure. The Normal, Log-Normal, Weibull and Gamma probability density functions were tested. Results show no significant changes in the shape and dimension in the forest structure dynamics, but a period of stability in the pattern of dendro/morphometric values, resulting from the stagnation of the values of the variables, non-intervention in the forest, relationship with the site, density, competition, and position of the tree in the forest stratum, which compromises the future structure of this forest typology. The study proves that the distribution probability of the variables can be used in management for species conservation and future structure development, as this influences the growth dynamics and processes, resource availability, and the stability, diversity, vitality, and productivity of the species.