INVESTIGADORES
ROUSSEAUX Maria Cecilia
artículos
Título:
Responses to solar ultraviolet-B radiation in a shrub-dominated natural ecosystem of Tierra del Fuego (southern Argentina).
Autor/es:
ROUSSEAUX, M. C.; SCOPEL, A.L.; SEARLES, P.S; CALDWELL, M.M.; BALLARE, C. L.
Revista:
GLOBAL CHANGE BIOLOGY
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Año: 2001 vol. 7 p. 467 - 478
ISSN:
1354-1013
Resumen:
A study was made of the effects of solar ultraviolet-B radiation (UV-B) on the growthof the dominant plant species of a shrub-dominated ecosystem in Tierra del Fuego.This part of southern Argentina can be under the direct influence of the Antarctic`ozone hole' during the austral spring and lingering ozone-depleted air during thesummer. The plant community is dominated by an evergreen shrub (Chiliotrichum diffusum)with an herbaceous layer of Gunnera magellanica and Blechnum penna-marinain the interspaces between the shrubs. Inspections of ozone trends indicate that thespringtime and summertime ozone column over Tierra del Fuego has decreased by 10±13% from 1978/9 to 1998/9. In a set of well-replicated field plots, solar UV-B wasreduced to approximately 15±20% of the ambient UV-B using plastic films. Polyesterfilms were used to attenuate UV-B radiation and UV-transparent films (~90% UV-Btransmission) were used as control. Treatments were imposed during the growing seasonbeginning in 1996 and continued for three complete growing seasons. Stem elongationof the shrub C. diffusum was not affected by UV-B attenuation in any of thethree seasons studied. However, frond length of B. penna-marina under attenuatedUV-B was signi®cantly greater than that under near-ambient UV-B in all three seasons.Attenuation of solar UV-B also promoted the expansion of G. magellanica leavesin two of the growing seasons. Differences between treatments in leaf or frond lengthin B. penna-marina and G. magellanica did not exceed 12%. Another significant effectof UV-B attenuation was a promotion of insect herbivory in G. magellanica, with a 25±75% increase in the leaf area consumed. Changes in plant phenology or relative speciescover were not detected within the time frame of this study. The results suggestthat the increase in UV-B radiation associated with the erosion of the ozone layermight be affecting the functioning of this ecosystem to some degree, particularly byinhibiting the growth of some plant species and by altering plant insect interactions.