Measurement of oak tree density with Landsat TM data for estimating biogenic isoprene emissions in Tennessee, USA

Isoprene emissions from oak trees in the eastern USA play an important role in tropospheric ozone pollution. Oak trees (Quercus) emit an order of magn itude more isoprene than most other emitting tree species, and are by far t he largest source of biogenic isoprene in the eastern US. We used Landsat T M data to measure oak tree abundance near Oak Ridge, Tennessee, to estimate fluxes of isoprene. The Landsat classification was performed using multi-d ate data, supervised classification techniques, and an iterative approach. Training sites were selected based on transect data, and ten vegetation cla sses were mapped. A supervised classification algorithm called the Spectral Angle Mapper was used to classify the data. Empirical vegetation emission data were used to estimate the isoprene flux from each of the vegetation cl asses. The resultant isoprene flux maps were compared with concentrations m easured in the field, and a good correspondence was observed. We also compa re the Landsat classification with three other landcover schemes including the USGS's Global Landcover Classification, which is based on AVHRR data. R esults from these landcover classifications are used as input for models th at predict tropospheric ozone production and are used to investigate ozone control strategies.