Sampling big sagebrush for phytomass.

Highlight: A double sampling procedure was employed for obtaining more reliable weight estimates for leaves, flowering stalks, live wood, dead wood, various combinations of the preceding, and total phytomass of sagebrush shrubs. Easily obtained dimension measurements were related to harvest categories using regression analyses. Volume (length x width x height) and length measurements were the most highly correlated to phytomass. Double sampling reduced the variance of the mean phytomass estimates ranging from 33% to 80% for the various categories assuming optimum allocation. The precision achieved by combining dimension measurements with harvesting is significantly higher than by harvests without supporting dimensional measurements.