Stand density index as a predictor of forage production in northern Arizona pine forests

Ponderosa pine Pinus ponderosa overstory-forage understory relationships were studied on the Kaibab Plateau to evaluate how well forage (graminoid, forb, and current year shrub) production could be predicted by stand density index. Stand density index, a relative measure of stand density, was a useful predictor of understory production for a variety of stand structures and ages. The linear and nonlinear equations produced coefficient determinations of 0.76 and 0.72, and standard error of the estimates of 5.08 kg ha^-1 and 5.51 kg ha^-1, respectively. -Authors