Pan-Arctic Vegetation Cover (PAVC) Gridded: High resolution fractional coverage maps of plant functional types at 20-meter spatial resolution

The PAVC-Gridded datasets were created to provide detailed fractional cover information for typical tundra plant functional types (PFTs) across Arctic Alaska, which will be embedded in terrestrial ecosystem models for improving carbon flux estimates. The PFT-level fractional cover also helps characterize the vegetation composition at sub-pixel level for understanding the tundra response to warming climate. This dataset includes 8 Tiff files containing fractional cover for 7 PFTs in the Arctic region of Alaska, USA. There are Tiffs for (1) bryophytes; (2) lichens; (3) non-vascular plants, i.e., the sum of lichens and bryophytes; (4) deciduous shrubs, (5) evergreen shrubs, (6) forbs, (7) graminoids, and a non-PFT class (8) litter. Each pixel in the Tiff file contains the cover (expressed as a fraction of total ground cover) that was predicted by a random-forest regression model. The random-forest models were trained on cover data collected at 978 plots from 2010 to 2021, of which are archived in the Pan-Arctic Vegetation Cover (PAVC) database (https://data.ess-dive.lbl.gov/datasets/doi:10.15485/2483557). The plot cover was linked to 20-meter spatial resolution, satellite-derived predictor variables: Sentinel-2 spectra and Sentinel-1 polarizations averaged over the 2019 growing season, as well as topographical features derived from ArcticDEM. Then, spatio-temporally anomalous plot data that introduced large variability to the regression outcomes were dropped using the Cook’s distance outlier detection method, and the models were re-created using high-quality plots and their associated satellite derived explanatory variables per each PFT. The correlations between plot-observed and satellite-derived fractional cover for all PFTs were well correlated (R2 = 0.69–0.95 and 0.5 for litter) and had low RMSE bias (0.02–0.11). This research was performed as a part of the NGEE Arctic project. The NGEE Arctic project was a research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research.