NEON Biorepository Terrestrial Plant Collection (Belowground Biomass [Standard Sampling])

Belowground biomass (root cores) collected at terrestrial NEON sites and archived as oven-dried material. Sampling Design Every five years Collected from randomly placed sampling cells (same used for annual aboveground herbaceous biomass sampling) within a Tower plot Two cores are taken from each sampling cell 20 m × 20 m small plots: one sampling cell (2 cores per plot) 40 m × 40 m large plots: two sampling cells (4 cores per plot) Sampling effort reduced by 50% at selected sites beginning in 2026 Methods Collected using a 3-inch outside diameter (6.65 cm inside diameter) corer to 30 cm depth Preservation Roots are sorted by size (<1 mm, 1–2 mm, 2–10 mm), oven-dried, and weighed Live/dead sorting discontinued in 2019; no species-level sorting Dried, weighed roots from each sampling cell are combined and ground <0.02g discarded; 0.02g-1g chemically analyzed only; >1 g chemically analyzed and excess material archived Archived material stored in 20 mL vials at room temperature