Sj. Goetz et al., Mapping net primary production and related biophysical variables with remote sensing: Application to the BOREAS region, J GEO RES-A, 104(D22), 1999, pp. 27719-27734
Maps of net and gross primary production, autotrophic respiration, biomass,
and other biophysical variables were generated for 10(6) km(2) of boreal f
orest in central Canada (the Boreal Ecosystem-Atmosphere (BOREAS) region) u
sing a production efficiency model (PEM) driven with remotely sensed observ
ations at 1 km(2) spatial resolution. The PEM was based on carbon yields of
absorbed photosynthetically active radiation for both gross and net primar
y production (GPP and NPP), accounting for environmental stress and autotro
phic respiration (R-a). Physiological control was modeled using remotely se
nsed maps of air temperature, vapor pressure deficit, and soil moisture. Th
e accuracy of the inferred variables was generally within 10-30% of point m
easurements at the surface and independent model results (both at the stand
level). Biomass maps were derived from visible reflectance measurements an
d were also compared to independently derived maps. Area-averaged GPP was 6
04 g C m(-2) yr(-1) compared with average canopy respiration of 428 g C m(-
2) yr(-1) and NPP of 235 g C m(-2) yr(-1). Net annual carbon uptake in net
primary production for the region totaled 175 teragrams. Canopy carbon exch
ange (GPP and R-a) differed widely between land cover types even though the
model does not use land cover information. Extensive areas of the least pr
oductive cover types (e.g., lowland needleleaf species) accounted for the g
reatest amount of NPP.