GLOBAL WARMING AND SOIL MICROCLIMATE: RESULTS FROM A MEADOW-WARMING EXPERIMENT1

摘要: We used overhead infrared radiators to add a constant increment of~ 15 W/m2, over 2 yr, to the downward heat flux on five 30-m2 montane meadow plots in Gunnison County, Colorado, USA. Heating advanced snowmelt by~ 1 wk, increased summer soil temperatures by up to 3 C, and reduced summer soil moisture levels by up to 25% compared to control plots. Soil microclimate response to heating varied with season, time of day, weather conditions, and location along the microclimate and vegetation gradient within each plot, with the largest temperature increase observed in daytime and in the drier, more sparsely vegetated zone of each plot. Day-to-day variation in the daily-averaged temperature response to heating in the drier zone was negatively correlated with that in the wetter zone. Our experimental manipulation provides a novel and effective method for investigating feedback processes linking climate …