Evaluation of the Article “Estimating Herbaceous Biomass of Grassland Vegetation Using the Reference Unit Method” by Boyda, et al. 2015
An evaluation of the scientific article “Estimating Herbaceous Biomass of Grassland Vegetation Using the Reference Unit Method” by Boyda, et al. 2015 (Prairie Naturalist) is relevant because authors state that herbaceous biomass can be accurately and precisely estimated throughout the entire Buffalo Gap National Grasslands (BGNG) and beyond with the Reference Unit Method. The authors failed to provide easy to follow methods, a complete data set with all results, a study site map while only providing partial data and analyses for prairie dog colonies or areas adjacent to prairie dog colonies. The authors did not provide an improvement in protocol and methodology of the weight estimated method (double sampling-estimating and clipping) described by Pechanec and Pickford (1937) and its application on rangelands to estimate above ground biomass for many ecological types. Evaluations were very limited to few plant species: western wheatgrass (Pascopyrum smithii), purple three-awn (Aristida purpurea), needle-and-thread (Hesperostipa comata), and green needle grass (Nassella viridula). Other comparisons were groups of plants with unidentified species and may produce questionable results with different species mixes when applied to other grasslands or locations on the BGNG. The protocols developed with double sampling (clipping with oven dry weights and corrected to visual estimates) is still the standard with no improvement by Boyda et al. (2015). The article by Boyda et al (2015) may provide erroneous results with application of the Reference Unit Method and is not recommended for estimating herbaceous biomass.
Key words: estimating biomass, double sampling, grasslands, plant biomass.