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Abstract:
Aim To infer a forest carbon density map at 0.01° resolution from a radar remote
sensing product for the estimation of carbon stocks in NorthernHemisphere boreal
and temperate forests.
Location The study area extends from 30° N to 80° N, covering three forest
biomes – temperate broadleaf and mixed forests (TBMF), temperate conifer forests
(TCF) and boreal forests (BFT) – over three continents (North America, Europe
and Asia).
Methods This study is based on a recently available growing stock volume (GSV)
product retrieved from synthetic aperture radar data. Forest biomass and spatially
explicit uncertainty estimates were derived from the GSV using existing databases
of wood density and allometric relationships between biomass compartments
(stem, branches, roots, foliage). We tested the resultant map against inventorybased
biomass data from Russia, Europe and the USA prior to making
intercontinent and interbiome carbon stock comparisons.
Results Our derived carbon densitymapagreeswellwith inventory data at regional
scales (r2 = 0.70–0.90).While 40.7 ± 15.7 petagram of carbon (Pg C) are stored in
BFT, TBMF and TCF contain 24.5 ± 9.4 Pg C and 14.5 ± 4.8 Pg C, respectively.
In terms of carbon density, we found 6.21 ± 2.07 kg C m−2 retained in TCF
and 5.80 ± 2.21 kg C m−2 in TBMF, whereas BFT have a mean carbon density of
4.00 ± 1.54 kg C m−2. Indications of a higher carbon density in Europe compared
with the other continents across each of the three biomes could not be proved to be
significant.
Main conclusions The presented carbon density and corresponding uncertainty
map give an insight into the spatial patterns of biomass and stand as a new
benchmark to improve carbon cycle models and carbon monitoring systems. In
total, we found 79.8 ± 29.9 Pg C stored in northern boreal and temperate forests,
with Asian BFT accounting for 22.1 ± 8.3 Pg C.
