A test of a single disk for estimation of hardwood bole and branch nutrient concentrations.

A single bole disk did not provide nutrient concentrations within + or -10% of the individual tree nutrient levels, unless a 1-in-20 chance occurred. However, the mean wood N, P, and K concentrations of a sample of 1/2-height bole disks were within + or -10% of the mean of bole concentrations for that sample. A single branch disk subsample was unable to satisfy accuracy standards for crown nutrient concentration estimates. Results indicate the necessity of sampling at least several trees per stand and intensive sampling of the tree crown for nutrient evaluations.-from Authors