Modelado de índices de competencia para Araucaria angustifolia en dos sitios en el sur de Brasil

Abstract

This study aimed at modeling competition indices for individual trees of Araucaria angustifolia in natural forests. A total of 397 objective trees were sampled in Lages and São Francisco de Paula municipalities. Through a non-linear regression analysis, 22 distance-independent and distance-dependent competition indices were modeled based on the diameter at breast height (d) and relative height (hrel: ratio between the total height of the objective tree and the maximum potential height estimated for the same diameter). The adjusted equations of the indices according to d of the objective tree achieved values of R² ≤ 0.546 (Syx% ≥ 15.0). The independent variable hrel improved the estimates, explaining up to 63 % of the variation in the data (Syx% ≥ 14.6). In general, competition indices -which consider in the calculation only the variables d of the objective tree, d of the competitors, its horizontal distance and eventually the height variable-showed superior performance. Therefore, they are indicated for use in growth modeling of A. angustifolia, due to superior facility of application in natural forests. The developed equations showed to be good representations of the degree of competition at the level of the individual tree of A. angustifolia for the two evaluated sites, measuring only the diameter or including the height of the objective tree for more accurate precision. The expansion of research to other sites along the distribution of the species will confirm the application of these equations to their full extent. In addition, this work contributes to the inclusion of competition indices in modeling of individual trees in uneven-aged mixed forests.

Individual models for diameter and height projection with contribution of competition index in Pinus taeda L. stands

“…The competition between trees clearly affected the growth rate, being the crown volume the variable that most contributed for competition. Schons et al (2020) highlighted the competition index of LO in the correlation between the competition indexes and the periodic increment in transversal area for some species of the Mixed Ombrophylous Forest, in the National Forest of Irati, Paraná state, Brazil.…”

“…There are still semi-independent distance indexes, representing the most recent class of these competition indexes. The most used competition indexes are described in Costa et al (2020). These indexes represent an important tool for forest management (PEDERSEN et al, 2013).…”

“…79696 1821973 -BAL), thus being included in the models to project diameter and height. These indices are presented inCosta et al (2020) eSchons et al (2020). The indexes were calculated with the expressions to follow.…”