PARENT SESSION
Oral Session #106: Plant Ecology: Global Climate Change.
Presiding: D. Breshears
Friday, August 9. 9:00 AM to 12:00 PM. Grand Ballroom East, Radisson.
Four years of warming enhances biomass and seed production, and litter accumulation in Antarctic tundra.
DAY, THOMAS*,1, RUHLAND, CHRISTOPHER1, XIONG, FUSHENG1, 1 Arizona State University, Tempe, AZ
ABSTRACT- Air temperatures are rising along the west coast of the Antarctic Peninsula, although little is known about what impact this is having on terrestrial ecosystems there. We passively warmed tundra along the Peninsula for four growing seasons to assess its impact on aboveground biomass production and reproductive output of the two Antarctic vascular plant species, Colobanthus quitensis (a cushion plant) and Deschampsia antarctica (a tussock grass). We also examined the influence of warming on litter accumulation and soil properties. The treatments were effected by placing transparent filters around cylindrical frames to a different extent: for the warming treatment the filters completely surrounded the frames, raising diurnal and diel air temperatures by 2.3 and 1.3oC, respectively, while for controls the filters only extended around half of each frame, raising temperatures by 0.2oC. After four growing seasons, warming led to greater total aboveground biomass, primarily due to greater aboveground biomass of Colobanthus. The mass of the litter layer and the organic soil horizon were also greater with warming. While warming did not affect the total number of capsules (Colobanthus) or panicles (Deschampsia) produced, it led to faster development of reproductive structures in both species, such that the percentage of structures reaching maturity at the end of each growing season were consistently greater. With warming, Colobanthus capsules produced more seeds that were heavier, and total numbers and mass of seeds produced per ground surface area were greater. Deschampsia panicles tended to produce more spikelets under warming, and total numbers of spikelets produced per ground surface area were greater. Warming had little impact on trends in foliar cover over the four years of the experiment. Warming drastically improved the reproductive output of both plant species, which has likely contributed to their rapid expansion along the Peninsula in recent years.
KEY WORDS: antarctica, warming, productivity, reproduction