title: Impacts of solar ultraviolet-B radiation on terrestrial ecosystems of Tierra del Fuego (southern Argentina). An overview of recent progress.
abstract: The southern part of Tierra del Fuego, in the southernmost tip of South America, is covered by dense Nothofagus spp. forests and Sphagnum-dominated peat bogs, which are subjected to the influence of ozone depletion and to increased levels of solar ultraviolet-B radiation (UV-B). Over the last 5 years we have studied some of the biological impacts of solar UV-B on natural ecosystems of this region. We have addressed two general problems: (i) do the fluctuations in UV-B levels under the influence of the Antarctic ozone 'hole' have any measurable biological impact, and (ii) what are the long-term effects of solar (ambient) UV-B on the Tierra del Fuego ecosystems? In this paper, we provide an overview of the progress made during the first 4 years of the project. We highlight and discuss the following results: (1) ambient UV-B has subtle but significant inhibitory effects on the growth of herbaceous and graminoid species of this region (growth reduction < or = 12%), whereas no consistent inhibitory effects could be detected in woody perennials; (2) in the species investigated in greatest detail, Gunnera magellanica, the inhibitory effect of solar UV-B is accompanied by increased levels of DNA damage in leaf tissue, and the DNA damage density in the early spring is clearly correlated with the dose of weighted UV-B measured at ground level; (3) the herbaceous species investigated thus far show little or no acclimation responses to ambient UV-B such as increased sunscreen levels and DNA repair capacity; and (4) ambient UV-B has significant effects on heterotrophic organisms, included marked inhibitory effects on insect herbivory. The results from the experiments summarized in this review clearly indicate that UV-B influences several potentially important processes and ecological interactions in the terrestrial ecosystems of Tierra del Fuego.
authors.affiliation: IFEVA, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina. ballare@ifeva.edu.ar
authors.forename: C L
authors.initials: CL
authors.lastname: Ballaré
authors.forename: M C
authors.initials: MC
authors.lastname: Rousseau
authors.forename: P S
authors.initials: PS
authors.lastname: Searles
authors.forename: J G
authors.initials: JG
authors.lastname: Zaller
authors.forename: C V
authors.initials: CV
authors.lastname: Giordano
authors.forename: T M
authors.initials: TM
authors.lastname: Robson
authors.forename: M M
authors.initials: MM
authors.lastname: Caldwell
authors.forename: O E
authors.initials: OE
authors.lastname: Sala
authors.forename: A L
authors.initials: AL
authors.lastname: Scopel
mesh_terms: D000818:Animals; D001118:Argentina; D002734:Chlorophyll / Q000528:radiation effects; D017753:Ecosystem; D010944:Plants / Q000528:radiation effects; D013472:Sunlight; D014466:Ultraviolet Rays
chemical_list: D002734:Chlorophyll