Estimating pasture species biomass from canopy cover

Abstract

AbstractMany tools are available to measure total aboveground plant biomass in pastures, for instance the rising plate meter, but measuring the biomass contribution of individual species requires time‐consuming clipping and sorting. Pasture composition determines forage quality, carbon storage, and other ecosystem services, so an efficient nondestructive method for estimating biomass by species would be of great value. Seasonal allometric coefficients relating canopy cover to aboveground biomass were developed for individual species and for functional groups (grass, large forb, small forb) using ordinary least squares regression on data from a grazed multi‐species experimental pasture in Pennsylvania, and tested on an independent grazed experimental study. The models performed better in autumn than in spring, although performance varied greatly among species. The functional group models were generally more accurate than species‐specific models, even for estimating single species. Total grass and forb biomasses were predicted moderately well regardless of season. Unlike many allometric models, these were developed and tested on multiple years of data from grazed multispecies pastures. Although variability was high, the results have broad applicability in highly fertile mesic pastures, at least for dominant species.