Open top chambers and infrared lamps: A comparison of heating efficacy and CO2/CH4 dynamics in a Northern Michigan Peatland
College of Forest Resources and Environmental Science
Open top chambers (OTCs) and infrared (IR) lamps have been widely used for experimentally warming ecosystems, especially in high latitude and alpine regions. The efficacy of OTCs and IR lamps is variable, yet there has not been a direct, experimentally controlled comparison of these warming methods. We, therefore, implemented a factorial study in a northern Michigan peatland to test how warming and microtopography interacted to affect micrometeorological parameters and CO2 and CH4 flux rates. IR lamps significantly warmed the soil (5 cm depth; P < 0.05) by 1.4 and 1.9°C in 2009 and 2010, respectively, with the majority of warming occurring during nighttime hours. OTCs did not provide any long-term warming increase compared to control plots, which is contrary to OTC studies at high latitudes. By investigating diurnal heating patterns and micrometeorological variables, we determined that OTCs were not achieving strong daytime heating peaks and were often cooler than controls during nighttime hours. Temperate day-length, cloudy and humid conditions, and latent heat loss were factors that may have inhibited OTC warming. Warming treatments created mixed effects on gas flux components. Within drier, hummock plots, IR lamps significantly increased gross ecosystem production (GEP) but not ecosystem respiration (ER), whereas OTCs had no effect on GEP or ER in hummocks. In wetter, lawn plots, warming treatments had no effect on CO2 flux or CH4 flux. We show here that IR lamps are more effective than OTCs for studying how temperate peatlands may respond to increased temperatures.
Johnson, C. P.,
Pypker, T. G.,
Hribljan, J. A.,
Open top chambers and infrared lamps: A comparison of heating efficacy and CO2/CH4 dynamics in a Northern Michigan Peatland.
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