Canopy foliage subsample for archive (NEON sample class: cfc_chemistrySubsampling_in.archiveSampleID). Canopy foliage sampling is conducted at each NEON site once every 5 years, with interannual schedules chosen by Science and Field Operations leadership to optimize linkages with the Airborne Observation Platform (AOP). The timing of airborne data collection by the AOP, which coincides with the approximate timing of peak greenness, largely determines the timing of canopy foliage sampling at a given site. In sites dominated by woody cover (e.g., forests and shrubland), the general procedure is to sample at least one individual of each species found in the site-level, sun-lit canopy. For the more common species, replicates are taken, spanning whatever gradients are relevant to a site (topography, aspect, soil type, stand age, etc). In high-diversity sites, rare species are only sampled where feasible, meaning individuals with sun-lit leaves can be found in target plots. All samples are collected from Vegetation Structure plots, and each site has a target sample number proportional to its canopy diversity, as assessed using stem counts. Target taxa lists including per-species sample numbers were generated by NEON Science and are included in the Sampling Support Library (SSL). Subsamples for archive 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). Archived samples are stored at room temperature in 20 mL HDPE scintillation vials. See TOS Protocol and Procedure: Canopy Foliage Sampling (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 Plant Foliar Physical and Chemical Properties (C, N, S, P, chlorophyll, lignin, cations, and leaf mass per area) and Plant Foliar Stable Isotopes.