Canadian Forest Service Publications

Combining satellite lidar, airborne lidar, and ground plots to estimate the amount and distribution of aboveground biomass in the boreal forest of North America. 2015. Margolis, H.A.; Nelson, R.F.; Montesano, P.M.; Beaudoin, A.; Sun, G.; Andersen, H.-E.; Wulder, M.A. Can. J. For. Res. 45:838-855.

Year: 2015

Available from: Laurentian Forestry Centre

Catalog ID: 36073

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1139/cjfr-2015-0006

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Abstract

We report estimates of the amount, distribution, and uncertainty of aboveground biomass (AGB) of the different ecoregions and forest land cover classes within the North American boreal forest, analyze the factors driving the error estimates, and compare our estimates with other reported values. A three-phase sampling strategy was used (i) to tie ground plot AGB to airborne profiling lidar metrics and (ii) to link the airborne estimates of AGB to ICESat-GLAS lidar measurements such that (iii) GLAS could be used as a regional sampling tool. We estimated the AGB of the North American boreal forest at 21.8 Pg, with relative error of 1.9% based on 256 GLAS orbits (229 086 pulses). The distribution of AGB was 46.6% for western Canada, 43.7% for eastern Canada, and 9.7% for Alaska. With a single exception, relative errors were under 4% for the three regions and for the major cover types and under 10% at the ecoregion level. The uncertainties of the estimates were calculated using a variance estimator that accounted for only sampling error, i.e., the variability among GLAS orbital estimates, and airborne to spaceborne regression error, i.e., the uncertainty of the model coefficients. Work is ongoing to develop robust statistical techniques for integrating other sources of error such as ground to air regression error and allometric error. Small ecoregions with limited east–west extents tended to have fewer GLAS orbits and a greater percent sampling error. AGB densities derived from GLAS agreed closely with the estimates derived from both forest inventories (<17%) and a MODIS-based interpolation technique (<26%) for more southern, well-inventoried ecoregions, whereas differences were much greater for unmanaged northern and (or) mountainous ecoregions.

Plain Language Summary

In this study, biomass of the North American boreal forest is estimated at 2,180 Megatons with 46.6% for Western Canada, 43.7% for Eastern Canada, and 9.7% for Alaska with relative error below 4%. Biomass estimates usually closely match those derived from Canadian Forest Service-National Forest Inventory photo-plots and National Forest Inventory maps.

The researchers estimated the total above-ground forest biomass of the ecozones and broad forest cover types of the North American boreal forests (Alaska and Canada) with the associated uncertainty. They used a novel multiscale approach for going from ground inventory plots to airborne and then spaceborne LiDAR and imagery. The key scientific impact is that this approach shows viable options for sample-based characterizations of biomass using airborne/spaceborne LiDAR technologies.

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