THE POTENTIAL SENSITIVITY OF TROPICAL PLANTS TO INCREASED ULTRAVIOLET-B RADIATION

Little is known concerning the impact of stratospheric ozone depletion and increasing ultraviolet (UV)-B radiation on the phenology and grow th of tropical plants. This is because, ostensibly, tropical plants ar e already exposed to relatively high levels of UV-B radiation (relativ e to a temperate environment) and should, therefore, possess a greater degree of tolerance to increased UV-B radiation. In this brief review I hope to show that, potentially, direct and indirect effects on phot osynthesis, assimilate partitioning, phenology and biomass could occur in both tropical crops (e.g. cassava, rice) and native species (e.g. Cecropia obtusifolia (Bertol. Fl)., Tetramolopium humile (Gray), Nana sandwicensis L.). However, it should be noted that differences in sens itivity to UV-B radiation can be related to experimental conditions, a nd care should be taken to ensure that the quantity and quality of bac kground solar radiation remains at near ambient conditions. Neverthele ss, by integrating current and past studies on the impact of UV-B radi ation on tropical species, I hope to be able to demonstrate that photo synthesis, morphology and growth in tropical plants could be directly affected by UV-B radiation and that UV-B radiation may be a factor in species and community dynamics in natural plant populations in the tro pics.