PARENT SESSION
Wednesday, August 9, 8:00-11:30 am
COS 46 - Climate and global change I: carbon cycling
Chickasaw, Mezzanine Level, Cook Convention Center
Presiders: A Dikou and K Treseder
Consequences of global climate change: the effect of increased rainfall on carbon storage and transformation in a northern California grassland.
Thomsen, Meredith*,1, Suttle, Kenwyn2, 1 University of Wisconsin, La Crosse, La Crosse, WI2 University of California, Berkeley, Berkeley, CA
ABSTRACT- We examined the effects of an ongoing water addition experiment on carbon (C) storage and transformation in a northern California grassland. The experiment was designed to test alternative scenarios of increased annual precipitation, and includes ambient rainfall and winter (January to March) vs. spring (April to June) water additions. After five years, both watering treatments have increased grassland productivity, spring water addition more than winter. During the same time period, annual grass leaf tissue C:N decreased with increasing water inputs, both across treatments and in response to annual variability. Productivity and leaf nitrogen increases may result in part from the success of N-fixing plants in spring-watered plots. In the fourth year of the experiment, watering treatments had no effect on a common litter decomposition experiment using four species representative of major functional and phenological groups. However, spring and summer soil CO2 efflux that year was strongly increased by spring water addition, suggesting that the rate of decomposition could be increased by a lengthened period of soil water availability. Finally, after four years of water addition total soil C content was higher in spring water addition plots, with the greatest increases at depth (12 cm). This may reflect the increased plant productivity in spring rain plots. Further evaluation of the composition of the organic C pool in these soils will be necessary to determine the significance of this pattern for soil C storage.
Key words: Carbon storage, Ecosystem ecology, Annual grassland