XVI International Botanical Congess

Under field conditions, the effects of intensified UV-B radiation of 2.54, 4.25 or 5.31KJ.m-2, corresponding to 12%, 20%, and 25% ozone depletion on wheat field ecosystems were studied. The producers in this ecosystem were spring wheat, oat and weeds of dicotyls. The consumers were wheat aphids and other soil animals. The decomposers were bacteria, actinomycetes, and fungi. Generally, UV-B radiation decreased the height and biomass of plants, deferred phenological period and impelled the decrepitude of plants tested. The enhanced UV-B radiation altered the competitive balance between these plant species pairs. UV-B radiation enhancement led to decrease in biodiversity. The UV-B radiation decreased population quantity of wheat aphids, earthworms, and other soil animals at the later stage of wheat tillering. It was clear that under UV-B radiation enhancement not only the number of physiological groups of bacteria i.g. azotobacteria and nitrobacteria, etc. was reduced as well.