NPP Multi-Biome: Gridded Estimates for Selected Regions Worldwide, 1989-2001, R1

Most field data for net primary productivity (NPP) are for relatively small field sites that are effectively points when considered at the 0.5 x 0.5 degree scale commonly used in global biogeochemical models. Thus, direct comparison between field data and coarse resolution model outputs can be misleading. Consistent estimates of NPP for 0.5x0.5 degree grid cells were developed from 15 studies representing NPP in croplands, sparse vegetation, shrublands, grasslands, and forests worldwide. The data set contains 3654 cells with a subset of 2335 cells in which outliers were removed and all replicate measurements were aggregated for each cell. The data set is a contribution to the Global Primary Production Data Initiative (GPPDI). Total NPP ranged from 3 gC/m2/yr for sparse vegetation to 1235 gC/m2/yr in forest, while aboveground NPP ranged from 3 to 890 gC/m2/yr (Zheng et al. 2003). Zheng et al. (2003) discuss the potential problems in such data-model inter-comparisons and identify issues that must be considered during the aggregation of field-scale data to coarser spatial resolutions, usually in the form of grid cells. They evaluated the data set by comparison with existing literature and the widely used Miami model. The file NPP_Gridded_3654_cells.csv is suitable for biome level and overall analyses because of larger sample size. The file NPP_Gridded_2335_unique_cells.csv was derived from the larger file; however, outliers were excluded, replicate measurements were averaged out for each unique geographic locations, and cells classified as water, bareground, and urban were excluded. It is more appropriate for model/data inter-comparisons