Abstract
The aim of the present study was to model the crown volume in black wattle stands (Acacia mearnsii De Wild.) in Rio Grande do Sul, Brazil. The study was carried out in plots installed in black wattle stands in area where the plantations of the species are common. Two trees in each plot of average diameter were felled to determination total height, crown length (crown height) and crown width taken twice, each measurement oriented perpendicular to the other across the bole axis and parallel to the base of the crown. To calculate crown volume (cv) widths were taken every meter starting at the base of the tree bole. Stepwise, backward, and forward variable selection methods were used to formulate the volume equations. The combined variable squared diameter and crown height (d²ch) was the most highly correlated with crown volume (r=0.84). This in turn was the variable that was integrated into the selected model, both in the stepwise and forward selection methods. The equation cv = b1 d²ch + ei was the model that provided the best fit for predicting crown volume in black wattle stands, both in age rotation and in young stands. Key words: Acacia mearnsii; morphometry; stepwise; models.
Highlights
The equation cv = b1 d2ch + εi was the model that provided the best fit for predicting crown volume in black wattle stands, both in age rotation and in young stands
Black wattle (Acacia mearnsii De Wild.) is a tree species which is prominent today in the state of Rio Grande do Sul, and stands of the species rank among the most widely planted in region behind the genera Eucalyptus and Pinus
Other variables showing significant correlations with crown volume were the combination of the squared diameter with the total height (d2ht) and crown height
Summary
Black wattle (Acacia mearnsii De Wild.) is a tree species which is prominent today in the state of Rio Grande do Sul, and stands of the species rank among the most widely planted in region behind the genera Eucalyptus and Pinus. The high-quality wood from this species is ideal for pulp and paper production, and most of the wood is consumed in these industries (Stein and Tonietto, 1997). The species is cultivated by more than 10,000 small farms and plays an important socioeconomic role in the region (Oliveira et al, 2006). One of the characteristics of black wattle stands is the use of intercropping, especially in the early years including annual crops, such as watermelon, corn and cassava, and in later years along with cattle (Fleig et al, 1993; Mora, 2002; Muller, 2006). In intercropping systems where the soil nutrient conditions, temperature and water availability are not limiting factors and pests
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