An Indirect Method to Estimate the Aerial Biomass of Small Single-Stemmed Woody Plants

Abstract

The above-ground biomass of unbrowsed, and subsequently, browsed plants was estimated from measurements of plant height. Unbrowsed weight was estimated from the quadratic regression of plant weight on plant height. Browsed weight was estimated by inserting coefficients which were appropriate for a given proportion of the original height into the above quadratic equation for unbrowsed weight. Estimation of these coefficients involved 3 steps. (1) Sample plants were cut into sections, dried and weighed. From these data, quadratic relationships between weight and height or portion (%) of height were established. (2) Coefficients from these relationships were then plotted against percent height, and a polynomial regression fitted. (3) The polynomial regression was used to predict coefficients for any given percent height. These predicted coefficients could then be inserted into the original quadratic equation for full height for determination of the weight of any given proportion of the full height. The technique depends on a good relationship between plant height and weight, such as might be expected to occur with the unbranched shoots of suckering aspen (Populus tremuloides). It is useful where nondestructive estimation of the aerial biomass of browsed plants is required, and it avoids the tedious measurement of the diameter of browsed stems.