Core Sampling for Plant Belowground Biomass Below-ground biomass represents a substantial component of the total plant biomass and plant carbon in terrestrial ecosystems, yet belowground biomass stocks and turnover remain very poorly understood both in space and in time. Developing a better understanding of belowground plant biomass, as well as how much of that biomass is produced and decomposed within a given year, is therefore crucial to improving our understanding of how terrestrial ecosystems respond to environmental changes. Below-ground biomass samples are collected every five years at SRER and provide insight into how fast biomass is produced and decomposed. Two below ground biomass cores (7.6 cm diameter x 30 cm deep) are collected at previously determined random locations within each of the Tower Plots (n = 18). Core samples within each plot are combined for a total of 18 samples per bout. Samples are sieved to remove soil, picked to separate roots from other organic material, and roots are then sorted into diameter size classes. NEON will perform a one-time assessment of this biomass pool per site during the first 5 years of Operations, and standard root sampling events will adopt a 1 cm length cutoff.