s, of their variables are presented clearly, in english, in terms which should be familiar to the reader. A chart is included which lists the parameters, units, description of the parameter, and the equation(s) the parameter is used in. The chart is a useful reference, for the reader, making it easy to determine what a variable stands for.
A single problem, in understanding the authors' definition of variables, was found in the way that the slope of a tree's canopy is defined. The authors defined slope as s = R/z where R is the cone radius of the tree at depth z (858). This measures the slope as a horizontal measurement divided by a vertical measurement. This is the opposite from what is usually expected. Students, of mathematics, who have taken algebra, geometry and calculus associate slope with a measure of the vertical over the horizontal. This required a shift in traditional thinking.
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