Belowground biomass subsample for archive (NEON sample class: bbc_chemistryPooling_in.bgcArchiveID). NEON Tower Plots are sampled for plant fine root biomass every 3-5 years to a maximum depth of 30 cm, and these samples are gathered either with relatively large diameter cores (5-10 cm diameter), or by cutting monoliths with a soil knife (with approximate surface dimensions of 10 cm [W] x 10 cm [L]). Samples are cored to 30 cm depth in order to be consistent with the sampling depth used for soil biogeochemistry and microbe sampling. Roots are sorted to two status classes (live or dead) and the following size category bins: < 0.5 mm, 0.5-1 mm, 1-2 mm, and 2-10 mm. Dead roots are not archived. A subsample of the each size class of live roots are archived if the total pooled dry mass for a size class is greater than 1 gram (enough material is available after analyses for stable isotopes and chemical properties) . Archived samples are oven-dried at 65 degrees Celsius for at least 48 hours then ground in a Wiley mill to 20 mesh size (sieve opening size = 0.0331 in) then transferred to a 20 mL HDPE scintillation vial. Archived samples are stored at room temperature. See TOS Protocol and Procedure: Soil Pit Sampling for Plant Belowground Biomass (https://data.neonscience.org/documents) for more information about this sample class. NEON datasets (https://data.neonscience.org/home) associated with this sample class include Root Stable Isotopes, Root Chemical Properties, and Root Sampling Tower Plots .