Using Landsat TM data to estimate carbon release from burned biomass in anAlaskan spruce forest complex

Fire disturbance in boreal forests can release carbon to the atmosphere sto red in both the aboveground vegetation and the organic soil layer. Estimati ng pyrogenic emissions of carbon released during biomass burning in these f orests is useful for understanding and estimating global carbon budgets. In this work, we have developed a method to estimate carbon efflux for the bu rned black spruce in an Alaskan forest by combining information derived fro m Landsat Thematic Mapper (TM) data and field measurements. We have used th e spatial and spectral information of TM data to identify and measure two i mportant factors: pre-burn black spruce density and burn severity. Field me asurements provided estimates of aboveground and ground layer carbon per un it area for the pre-burn Landsat spectral classes, and percentage of carbon consumed for the post-burn Landsat spectral classes. Carbon release estima tes for the burned black spruce were computed using field data and the co-o ccurrence of the preburn and post-burn spectral classes. The estimated carb on released was 39.9 t ha(-1) which is 57% greater than an estimate compute d using AVHRR data and estimates of pre-burn biomass and carbon fractions c onsumed that were not site specific or spatially varying. We conclude that the spectral bands and spatial resolution of Landsat TM data provide the po tential for improved estimates of pyrogenic carbon efflux relative to the c oarser spectral and spatial resolution of other multispectral sensors.