Industrial and anthropogenic emissions of trace gases, especially chlorofluorocarbons (CFC's) that contain fluorine, chlorine and bromine atoms are destroying the stratospheric ozone layer, which protects all living organisms on earth from excess amounts of harmful ultraviolet-B (280 - 320 nm) radiation.

Studies commenced at the NBI in 1992 to examine the potential effects of anticipated future increases in UV-B radiation due to ozone depletion on the physiology, growth and reproductive performance of South African taxa. These studies have concentrated on natural plants of importance to the tourism industry found in arid regions of South Africa, where the largest increases in UV-B radiation are expected to occur, and more recently on agriculturally important African seed legumes.

Experimental observations indicate a widespread detrimental effect of elevated UV-B on pollen quality and reproductive yield in South African arid plants of diverse systematic origin and floral architecture. Most striking are indications of carryover of UV-B damage to offspring, which exhibit progressively diminished vigour and reproductive capacity with increasing numbers of enhanced UV-B repetitions in their ancestry. Notable also is that many of the persistent changes in offspring are intensified under other environmental stress conditions, e.g. increased atmospheric CO2, which disagrees with current opinion that an expected doubling of atmospheric CO2 in the middle of the next century may reduce or negate detrimental UV-B effects on plants.

Mapping UVB increases (large image)