Data from C. Anton-Fernandez and Colleagues Advance Knowledge in Forestry
2012 JUN 7 (VerticalNews) -- By a News Reporter-Staff News Editor at Agriculture Week -- Current study results on Forestry have been published. According to news originating from Blacksburg, Virginia, by VerticalNews correspondents, researchers stated "Several studies have reported that in loblolly pine stands with high initial density, basal area declines after reaching maximum carrying capacity. This behavior is not reproduced by most basal area development models because the functions used are sigmoid and nondecreasing, tending toward an asymptote."
Our news journalists obtained a quote from the research by the authors, "We used a combined exponential and power function to model the impact of initial density on the basal area development of loblolly pine in a spacing trial. The combined exponential and power function is sufficiently flexible to describe both the asymptotic behavior of the wider initial spacing plots and the decrease in basal area after culmination of the closer spacings. We modified the original function to account for the time lag between stand establishment (age = 0) and basal area establishment (age > 0), by allowing the origin of the function to be different than age = 0. Two final models are presented: a model fitted using the population-average (PA) approach and a model fitted using the mixed-effects (ME) approach. At the fixed-effects level, the PA and ME models are not equivalent, and, therefore, the appropriate model should be selected according to the availability of previous data and the objectives of the prediction."
According to the news editors, the researchers concluded: "If previous observations are available, they can be used to improve the predictions using the ME model. FOR. SCI. 58(2):95-105."
For more information on this research see: Modeling the Effects of Initial Spacing on Stand Basal Area Development of Loblolly Pine. Forest Science, 2012;58(2):95-105. Forest Science can be contacted at: Soc Amer Foresters, 5400 Grosvenor Lane, Bethesda, MD 20814, USA.
The news correspondents report that additional information may be obtained from C. Anton-Fernandez, Virginia Technical, Blacksburg, VA, United States.
Keywords for this news article include: Virginia, Forestry, Blacksburg, United States, North and Central America
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