Dehai Zhao, Michael Kane, Bruce E. Borders
Warnell School of Forestry and Natural Resources, University of Georgia, Athens, USA.
DOI: 10.4236/ojf.2012.23014   PDF    HTML     8,322 Downloads   19,117 Views   Citations

Abstract

Two loblolly pine (Pinus taeda L.) culture/density studies were established in 1995-1998 across the Lower Coastal Plain and Upper Coastal Plain/Piedmont regions of the southern USA. Each installation contains 12 plots of loblolly pine planted at six levels of density from 741 to 4448 trees/ha in combination with two levels of cultural intensity, operational and intensive. The data from 37 viable installations were used to evaluate the crown ratio and relative spacing relationship of loblolly pine plantations. The effects of planting density, site quality, and cultural intensity on the relationship were investigated with a nonlinear mixed-effects modeling approach. The crown ratio and relative spacing relationship is exceedingly predictable. When loblolly pine plantation stands reached the average live crown ratio of 0.40, a critical point representing a generally acceptable level of tree vigor, the corresponding relative spacing index ranged from 0.11 to 0.20, mainly depending on initial planting density. The information about the crown ratio and relative spacing relationship would be useful for selecting the best intensity and timing of thinning.

Keywords

Loblolly Pine; Intensive Culture; Planting Density; Live Crown Ratio; Relative Spacing Index

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Conflicts of Interest

The authors declare no conflicts of interest.

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