| Summary: | This study tested the hypothesis that the thickness of the pollen wall will increase in response to enhanced UV-B irradiation, by examining the effect of enhanced UV-B irradiance on the pollen morphology of Salix polaris Wahlem. grown in a field experiment on the Arctic tundra of Svalbard. Measurements of pollen morphology were conducted by light microscopy on plants grown at two sites, Adventdalen and Isdammen. Salix vegetation was grown under control, enhanced UV-A, and two enhanced UV-B (simulating 15 and 30% reduction in the thickness of the stratospheric ozone layer) treatments. At the Adventdalen site, pollen wall thickness significantly increased under enhanced UV-A and UV-B treatments compared with the control. A thicker pollen wall helps to prevent damage by UV-B radiation of the DNA of the pollen. In contrast, plants at the Isdammen site did not exhibit any significant pollen morphological response to the enhanced UV treatments. The inconsistency in plant response to enhanced UV treatments between the two sites may be explained by greater habitat heterogeneity at the Isdammen site; abiotic soil conditions including nutrient and water availability may also have an influence on pollen morphology.
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