ESTIMATION PROCEDURES FOR UNDERSTORY BIOMASS AND FUEL LOADS IN SAGEBRUSH STEPPE INVADED BY WOODLANDS

摘要

Regression equations were developed to prediet biomass for 9 shrubs 9 grasses old 10 forbs that gener ally dominate sagebrush ecosystems in central Nevada Independent variables included percent cover average height and plant volume We explored 2 ellipsoid volumes one with maximum plant height and 2 crown diameters and another with live crown height and 2 crown diameters Dependent variables were total live and dead biomass Simple multiple line u and power equations were investigated Models were chosen based on scatter plots residual plots and R-2 and SEE values In general simple power equations piovided the best fit regressions For shrubs the ellipsoid volume computed with maximum plant height best predicted total plant weight and the ellipsoid volume computed with the live crown height best predicted shrub foliage weight In addition to regression equations for biomass ratios for division of that biomass into 1 10 100 and 1000 hour fuels were derived fin common large shrubs Regression equations were also derived to relate litter mat sizes of maim shrub species to litter weights The equations in this paper could he used to predict biomass in other areas of the Crest Basm if training data were taken to validate or adjust these models