AGBref: A global reference dataset of above-ground forest biomass

The main hurdle in validating global maps of forest above-ground biomass (AGB) is the lack of reference data, particularly for validating maps that represent different epochs and spatial resolutions. Here we introduce AGBref the first global AGB reference dataset derived from a collection of National Forest Inventories (NFI), permanent research plots and local AGB maps from airborne LiDAR. This dataset provides biomass estimates for multiple epochs (2005, 2010, 2015, 2020) at various spatial resolutions or supports (500 m, 1 km, 10 km, 25 km). More importantly, the dataset comes with uncertainty estimates stemming from plot measurement errors and the biomass variability at different supports (within-pixel variability). AGBref also comes with a series of quality flags that inform users about the characteristics of grid cells according on the attributes of the plots within them. We further examine how filtering based on quality flags influences the representativeness of AGBref globally and across major biomes.