Measurement of Herbaceous Biomass
Herbaceous vegetation (operationally defined in this protocol as non?woody plants as well as woody?stemmed plants with a diameter at decimeter height < 1 cm at the time of sampling) can respond relatively rapidly to various global change drivers.  Understanding long?term trends in herbaceous community structure and biomass is very important in grazed ecosystems where these plants constitute a critical food source for wildlife and livestock.    Herbaceous biomass clip?harvests at SRER occurs annually at peak green in randomly assigned clip?harvest strips (0.1 m x 2 m) located within all Tower Plots (n = 18) and once every three years in a subset of Distributed Plots (n = 20).  In sites where grazing is an important part of the management practice (e.g., SRER) NEON employs grazing exclosures to estimate the productivity that is consumed by grazing herbivores. Clip harvest data can be used to estimate the amount of herbaceous biomass produced within the delineated clip strip area. The material collected is sorted into functional groups and weighed to determine Net Primary Production. Herbaceous biomass sampling for biogeochemistry is a separate clip harvest effort that is used to analyze the chemicals in the clipped biomass and is performed every five years.  Biogeochemistry clip harvest occurs at a subset of Tower Plots (n = 4) and Distributed Plots (n = 16).