CHRONIC OZONE EFFECTS ON 3 NORTHEASTERN HARDWOOD SPECIES - GROWTH ANDBIOMASS

The response of black cherry (Prunus serotina Ehrh.), sugar maple (Ace r saccharum Marsh.), and yellow-poplar (Liriodendron tulipifera L.) se edlings after being exposed to two seasons of ozone ranging from subam bient to twice ambient (exposures ranged from 16 to 107 ppm . h in 199 0 and 31 to 197 ppm . h in 1991) was studied in standard 3-m diameter open-top chambers. All three species responded differently to ozone. A fter one season of exposure, black cherry growth and biomass decreased with increasing ozone exposure; yellow-poplar growth and biomass incr eased with increasing ozone exposure; and sugar maple growth and bioma ss were not significantly affected by ozone. After two seasons of expo sure, few to no effects from ozone were observed in either sugar maple or yellow-poplar. However, total plant and root biomass of black cher ry exposed to twice ambient ozone were reduced 32 and 39%, respectivel y, when compared with those grown in charcoal-filtered air. Exposure-r esponse relationships were either linear or quadratic for most of the growth and biomass parameters measured.