GLOBAL WARMING AND SOIL MICROCLIMATE - RESULTS FROM A MEADOW-WARMING EXPERIMENT

摘要

We used overhead infrared radiators to add a constant increment of approximate to 15 W/m(2), over 2 yr, to the downward heat flux on five 30-m(2) montane meadow plots in Gunnison County, Colorado, USA. Heating advanced snowmelt by approximate to 1 wk, increased summer soil temperatures by up to 3 degrees 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, soil, and vegetation. [References: 36]