Global change and the effects of solar UV radiation on terrestrial ecosystems

BALLARÉ CL

São Jose dos Campos, SP

Simposio; FIRST BRAZILIAN SYMPOSIUM ABOUT THE EFFECTS OF INCREASED UV RADIATION ON AGRICULTURE; 2010

Universidade do Vale do Paraíba, Instituto de Pesquisa e Desenvolvimento

UV radiation (280-400 nm) is a minor component of the solar spectrum reaching the ground surface; yet, it has important effects on organisms and biogeochemical cycles. Many research efforts during the past two decades have thoroughly characterized the effects of the UV-B (280-315 nm) component. In this talk, I will summarize the lessons from this previous work, and highlight some of the important knowledge gaps in connection with the effects of climate change. I will address the following points. A) The effects of UV-B radiation on the growth (biomass accumulation) of terrestrial plants are relatively small. B) On the other hand, UV radiation affects plant secondary chemistry and the activities of canopy arthropods and phyllosphere microorganisms. Therefore, trophic interactions in terrestrial ecosystems are likely to be significantly affected by future variations in UV irradiance. C) Changes in UV resulting from climate change (e.g., variations in cloud cover) may have more important consequences on terrestrial ecosystems than those derived from ozone depletion. This is because the resulting variations in UV may affect a greater range of ecosystems, and will not be restricted solely to the UV-B component. D) Several processes that are not particularly sensitive to UV-B can be strongly affected by UV-A radiation. One example is the physical degradation of plant litter. UV-induced changes in photodegradation may have direct and indirect effects on carbon sequestration in terrestrial ecosystems.