Determining successional stage of temperate coniferous forests with Landsat satellite data

Thematic Mapper (TM) digital imagery was used to map for-est successional stages and to evaluate spectral differencesbetween old-growth and mature forests in the central Cas-cade Range of Oregon. Relative sun incidence values wereincorporated into the successional stage classification tocompensate for topographic induced variation. Relative sunincidence improved the classification accuracy of youngsuccessional stages, but did not improve the classificationaccuracy of older, closed canopy forest classes or overall ac-curacy. TM bands 1, 2, and 4; the normalized difference veg-etation index (typo); and TM 4/3, 4/5, and 4/7 band ratiovalues for old-growth forests were found to be significantlylower than the values of mature forests (P 0.034). The Tas-seled Cap features of brightness, greenness, and wetness alsohad significantly lower old-growth values as compared tomature forest values (P 5_ 0.010). Wetness and the TM 4/5and 4/7 band ratios all had low correlations to relative sunincidence (r2 0.16). The TM 4/5 band ratio was named the"structural index" (sr) because of its ability to distinguishbetween mature and old-growth forests and its simplicity.