Spatially-explicit landscape level biomass estimation: issues and an approach for areas where ground data is lacking

The estimation of forest stand biomass generally involves a conversion of inventory volume to biomass, where the inventory volumes are generated from interpreted values for stand level cover-type and crown closure. Information on land cover and crown closure may be obtained from forest inventory data and/or remotely sensed data. As a result, inventory data and remotely sensed images can be used independently or combined to estimate biomass. The forest inventory approach to landscape level biomass estimation is incomplete, as many areas do not have an inventory estimate of volume or other auxiliary variables that would allow for a prediction of biomass. Remotely sensed information can be used to impute the missing biomass information through remote estimation of cover-type and crown closure. When tested in a 7500 km² area in the Canadian province of Saskatchewan this hybrid approach to landscape level estimation of biomass was found to add an additional 36.2% of biomass to the total. While remote sensing has reduced capabilities for defining species type and crown closure, it has shown considerable advantage in allowing mapping over areas with non-commercial stand types as well as for map update between inventory programs