Composite Site Productivity Index (CSPI) v2.0.0 for the conterminous United States: 30 m multi-metric composite of Environmental Site Index, Biomass Growth Increment, Asymptotic Biomass, and Net Primary Production

Version 2.0.0 of the CSPI concept (concept DOI 10.5281/zenodo.20515034). This release replaces the FIA condition-level site index (SICOND) target used in v1.0.0 (10.5281/zenodo.20515035) with a unified North America height-and-age compilation, and extends the product from a single-metric Environmental Site Index to a true multi-metric Composite Site Productivity Index. Headline product: CSPI_v2_4component_30m.tif, a 30 m wall-to-wall composite for the conterminous United States built as the z-score weighted average of four independently fitted productivity layers: (1) Environmental Site Index (ESI v7, 30 m), (2) Biomass Growth Increment from FIA remeasurement pairs (BGI, 30 m), (3) Asymptotic aboveground biomass from a Chapman-Richards fit (Asym, 30 m), and (4) MODIS MOD17A3HGF net primary production 2017-2023 mean (NPP, 500 m). Each component is standardized using plot-level z-score parameters at the 40,933 complete-case FIA plots, sigma-clipped at 3 standard deviations, averaged with equal weights, and rescaled to 0 to 100. Supporting layers released as separate files: ESI v5 (30 m, climate-free baseline), ESI v6 (1 km, in-region accuracy champion), ESI v7 (30 m, recommended ESI), an ESI hybrid blend (latitude-weighted v5 + v6), the BGI and Asym component layers, MOD17 NPP mean and CV at 500 m, ESI v7 forest mask and quantile-RF uncertainty, and the CSPI v2 forest mask and uncertainty. Retained from v1.0.0: the original SICOND-target CSPI v3 (30 m), CSPI v4 (1 km combined), and their forest masks and v4 uncertainty layers, for users who need the FIA SICOND target. Nomenclature note: the v1.0.0 release used the name CSPI for what is now called ESI (a predicted site index from environmental covariates). In v2.0.0 we reserve CSPI for the true multi-metric composite. The v1.0.0 product names are unchanged for citation stability. Headline accuracy: ESI plot-blocked 5-fold cross-validated R squared is 0.664 for v5, 0.699 for v6, and 0.686 for v7. Spatial latitude-fold CV R squared is 0.358 for v5, 0.272 for v6, and 0.427 for v7. ESI v7 enters the composite. The CSPI v2 composite at 40,933 complete-case FIA plots has component pairwise correlations between -0.46 (ESI vs BGI) and +0.21 (ESI vs NPP); leave-one-component-out sensitivity preserves r >= 0.77 against the full composite for any 3-of-4 subset. See README.md for the file list, citation guidance for headline vs component use, and the full data dictionary.