Evaluation of Double-Sampling Estimators of Subalpine Herbage Production

Electronic capacitance metering, relative and dry weight estimations, and canopy cover estimation of herbaceous standing crops were statistically evaluated with respect to sampling costs, precisions, and the vegetal and environmental factors which affected their double-sampling correlations. Twenty-four factors were investigated using stepwise regression analysis. Minimum sampling costs were achieved when the double-sampling estimator technique was compatible with the characteristics of the sampling site. Relative and dry weight estimations were found to be consistently precise estimators in meadow, aspen, fir, and spruce-fir, and spruce-fir vegetation types. Both were successfully used by workers with no prior experience or training. The sampling techniques were capable of providing, at equal sampling cost, up to a 4-fold increase in sample size over that of clipping along, depending on the vegetation type.