EFFECT OF FIRE INTENSITY ON UNDERSTORY COMPOSITION AND DIVERSITY IN AKALMIA-DOMINATED OAK FOREST, NEW-ENGLAND, USA

This study investigates the understory dynamics of two mixed-oak stand s following fire of varying intensity. Composition and diversity of wo ody and herbaceous species in the understory were measured in two stan ds 7-8 years after a prescribed burn. On both sites, unburned areas, l ow-intensity fire areas, and areas where the overstory had been severe ly damaged were measured. Patterns of species presence and absence fol lowing fire were consistent with an initial-floristics model. Most spe cies increased in density and frequency following fire; only Aralia nu dicaulis and Quercus alba showed statistically significant decreases i n density. Overall, 29 species increased in density following fire, wh ile 8 declined; 29 species increased in frequency, while 6 declined. H owever, diversity and equitability measures were depressed on the mode rately burned sites, due to rapid regrowth of Kalmia latifolia. Ordina tion using binary discriminant analysis suggested species responded in dividualistically to both burning and site variation.