PARENT SESSION
Poster Session #31: Climate Change.
Wednesday, August 8, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall
97
Long-term energy flows in peatlands and their responses to heat and water loading.
Pastor, John1, Chen, Jiquan2, Bridgham, Scott3, Deywey, Brad1, Marshall, Treneice2, Weltzin, Jake4, Harth, Cal1, Keller, Jason3, 1 2 3 4
ABSTRACT- This study was designed to examine feedbacks between energy balance and vegetation under different water and heat loading treatment in bogs and fens. Energy flows of net radiation (Rn) and soil heat (G) in 54 mesocosm plots have been continuously measured at 30-min intervals since Oct., 1998 using an automated energy budget system to detect underlying mechanisms that cause temperature changes. Each plot was randomly treated with one of 3 levels of water and infrared loading in a full-factorial design with 3 replications. Our long-term results indicate that there are no significant differences in Rn (P<0.02) among treatments. Large differences in G were recorded between fen and bog mesocosms, which suggests that vegetation plays a critical role in partitioning Rn. These differences were well reflected in soil vertical temperature gradients (Ts) and were related to physical properties (e.g., thermal conductivity). Three major temperature responses were elongated growing season, extremely high differences in late winter and early spring days, and lower temperature at heated plots. Ts at 40 cm in heated plots were >0 C in early March, 20 to 40 days before unheated plots reached the same level in April. Bogs appeared to be more sensitive than fens to Rn, G, and Ts. Most importantly, peatlands receiving infrared heat loading were significantly (maximum >4 C) cooler than unheated plots throughout the winter, likely because of reduction of snow cover.
KEY WORDS: mesocosm, climate, energy, peatlands