FIRE AND CYCLONE DAMAGE TO WOODY VEGETATION ON THE NORTH COAST OF THENORTHERN-TERRITORY, AUSTRALIA

Tree stem (>2 m tall) mortality was assessed following a late dry-seas on wildfire across a seasonally flooded elevation gradient at Workshop Jungle, near Darwin, in the Northern Territory of Australia. For all species combined, dead stems had significantly smaller diameter at bre ast height (dbh) than living stems. Assessment of tree-stem damage fol lowing a tropical cyclone at Cobourg Peninsula, NT, revealed that dama ged stems had significantly greater dbh than undamaged stems for all t ree species sampled across a boundary between monsoon rainforest and s avanna. A greater proportion of stems were damaged by the cyclone than by the fire (28 per cent as against 18 per cent), although there were considerable between-community differences in the proportion of damag ed stems at the two sites. The fire caused little impact (<10 per cent ) on total basal area of three different forest communities on the ele vation gradient at Workshop Jungle. The cyclone was found to cause >50 per cent damage to total basal area of three different communities on Cobourg Peninsula. It is suggested that the combination of a cyclone followed by an intense fire in storm debris could potentially destroy a monsoon rainforest through its impact on all tree-size classes. This may explain why some monsoon rainforests rapidly contracted following Cyclone Tracy that destroyed the city of Darwin on Christmas Day, 197 4.