Harmonized global maps of above and belowground biomass carbon density in the year 2010

Abstract

Remotely sensed biomass carbon density maps are widely used for myriad scientific and policy applications, but all remain limited in scope. They often only represent a single vegetation type and rarely account for carbon stocks in belowground biomass. To date, no global product integrates these disparate estimates into an all-encompassing map at a scale appropriate for many modelling or decision-making applications. We developed an approach for harmonizing vegetation-specific maps of both above and belowground biomass into a single, comprehensive representation of each. We overlaid input maps and allocated their estimates in proportion to the relative spatial extent of each vegetation type using ancillary maps of percent tree cover and landcover, and a rule-based decision schema. The resulting maps consistently and seamlessly report biomass carbon density estimates across a wide range of vegetation types in 2010 with quantified uncertainty. They do so for the globe at an unprecedented 300-meter spatial resolution and can be used to more holistically account for diverse vegetation carbon stocks in global analyses and greenhouse gas inventories.

New Biomass Estimates for Chaparral-Dominated Southern California Landscapes

“…Hereafter we refer to our AGLBM estimates as the WWETAC-UCD estimates. Following inspection of the WWETAC-UCD raster layers, we determined that predicted biomass of perennial grassland and desert scrub CWHR classes [38] was higher than field based estimates [57,58] by approximately 2 orders of magnitude, so we reduced AGLBM values for these classes by 99% and 90% respectively. All estimates of biomass are provided in kg/m 2 .…”

“…To view our AGLBM estimates in a broader context and to provide useful information for resource managers, we compared our 2010 WWETAC-UCD data to two contemporary spatial biomass estimates for the four southern USFS national forests: the Global Aboveground and Belowground Biomass Carbon Density Data for the year 2010 (NASA-ORNL at 300 m resolution) [57], and the statewide California Air Resources Board (ARB at 30 m resolution) carbon stocks for 2010 [58,59]. We converted the raster biomass data from these projects to kg/m 2 of biomass (rather than carbon) to compare with our WWETAC-UCD AGLBM estimates.…”

“…In contrast the ORNL-NASA -WWETAC-UCD delta values were much higher (2.3 kg/m 2 ) for shrub vegetation than non-shrub (0.78 kg/m 2 ). [57] vs field plot estimates; (c) AGLBM estimates from this study (WWETAC-UCD) vs field plot estimates. The ARB and ORNL estimates were for the year 2010 therefore we only used the 22 validation plots that were visited in 2010 for this analysis.…”

“…Table 3. Mean total above ground live biomass (AGLBM) estimates for the year 2010 for the four national forests in the study area using the methods developed in this paper (WWETAC-UCD), the California Air Resources Board (ARB) [58] and the Oak Ridge National Laboratory -NASA (ORNL-NASA) [57]. Mean biomass values (kg/m 2 ) for each forest were calculated from the 30 m resolution raster layers developed using each of the three methods.…”

“…In our case, the ARB aggregation of AGLBM by LANDFIRE classes resulted in their estimates by forest to be higher than ours (Table 3). Second, the ORNL-NASA project goal was to develop a global biomass dataset that captured the uncertainty surrounding both the above and below ground biomass estimates [57]. In developing their datasets, they leveraged the GlobBiomass project [73] for forested areas.…”