Carbon stores, sinks, and sources in forests of northwestern Russia: Can we reconcile forest inventories with remote sensing results?

Forest inventories and remote sensing are the two principal data sources used to estimate carbon (C) stocks and fluxes for large forest regions. National governments have historically relied on forest inventories for assessments but developments in remote sensing technology provide additional opportunities for operational C monitoring. The estimate of total C stock in live forest biomass modeled from Landsat imagery for the St. Petersburg region was consistent with estimates derived from forest inventory data for the early 1990s (272 and 269 TgC, respectively). The estimates of mean C sink in live forest biomass also agreed well (0.36 and 0.34 Mg C ha(-1) yr(-1)). Virtually all forest lands were accumulating C in live biomass, however when the net change in total ecosystem C stock was considered, 19% of the forest area were a net Source of C. The average net C sink in total ecosystem biomass is quite weak (0.08 MgC ha(-1) yr(-1) and could be reversed by minor increases in harvest rates or a small decline in biomass growth rates.