Impacts of climate change on Antarctic vascular plants: warming and UV-B radiation

Our research examined the influence of ultraviolet-B radiation
(UV-B) and warming on the performance of Antarctic flowering plants
(i.e. Deschampsia antarctica, Antarctic hairgrass and Colobanthus quitensis,
Antarctic pearlwort). Our research endeavors fell into the following
categories:

1) We conducted a long-term field experiment at Stepping
Stones, near Palmer Station, in which we reduced levels of UV
radiation and raised air temperatures around naturally growing
Deschampsia antarctica and Colobanthus quitensis plants for four
consecutive growing seasons. We examined plant responses to
these manipulations by assessing photosynthesis, vegetative growth,
cover, and sexual reproduction. At the end of this
experiment, we collected plant, soil and litter samples, and
examined treatment effects on plant biomass production, litter
accumulation, soil properties, and microarthropod populations.

2) Single growing-season experiments were also conducted
at Stepping Stones, primarily aimed at examining the influence of
UV-B radiation on plant growth processes and concentrations of
UV-screening compounds in leaves, and soil seed banks.

3) We also conducted a more intensive short-term experiment at
Palmer Station, in which we placed potted plants under UV-B transparent
or UV-B absorbing filters from November through late December,
corresponding to the ozone depletion/enhanced UV-B season.
We assessed the influence of ambient UV-B during the ozone depletion
period by examining UV-screening compound concentrations, and
rates of photosynthesis, plant growth and DNA damage.

4) To quantify the short-term UV-B responses of these species
under more controlled conditions, we examined the UV dose response
of DNA damage and screening compound concentrations in these species
in growth chamber studies at our home institution.

5) We examined the temperature response of antarctic plants,
by characterizing the photosynthetic and respiratory responses
of naturally growing plants to temperature at Palmer Station.
We also characterized their long-term, or acclimation, responses
to rising temperatures, in terms of photosynthesis, respiration and growth,
in a series of growth chamber experiments.