This document describes the measurement of ancillary vegetation variables at ICOS ecosystem stations in grasslands. These variables include Green Area Index (GAI), Aboveground Biomass (AGB), and litter biomass, and are in summary measured with the following methods: - GAI and AGB are assessed from direct measurements by destructive sampling and from plate meter measurements of bulk vegetation height, which are combined in a double sampling design. Destructive sampling involves clipping vegetation to a site-specific stubble height. Correction measurements for the remaining biomass and area in the stubble are done by infrequent destructive sampling of stubble. - GAI can alternatively be measured with a linear ceptometer in grasslands where only a small fraction of the vegetation is non-green and where the vegetation is not extremely short or sparse. - Litter biomass, which includes “natural” litter as well as harvest residues after cuttings, is measured from collected litter material. “Natural” litter should only be measured if relevant and doable. - In agricultural grasslands, AGB measurements are used to estimate cut and grazed biomass and might for the latter require grazing cages. The ancillary vegetation variables also include canopy height, the measurement of which is described separately in Appendix B. This document is structured in four different sections to facilitate the use and application: - Measurements: in this section the sensors, setup and methods to correctly collect the data and info are described. It includes sub-sections on sensors characteristics, practical indication for the setup/collection, info on the sampling design and guidelines for the installation/sampling also respect to other sensors/measurements - Maintenance: in this section all the maintenance and calibration guidelines are described. - Submission: it is the section related to the data preparation and submission to the ETC. It includes the list of all the parameters, the correct formatting and the way to submit them to the database. It is linked to the BADM system needed to submit the metadata and not continuous measurements - Processing: this section is for internal use of the ETC and describes the processing applied to the single variable/info/sample submitted. It is important to remind that the exact application of the protocol at station level is also discussed with the ETC in order to find agreed solutions for specific cases. If a specific part is relevant only for a specific ecosystem or station Class this is also reported in the document.