Diurnal and seasonal soil moisture variation along a forested and tegenerating clearcut hillslope in Colorado

Soils in midlatitude subalpine catchments play an important role in regulating the movement of melt water from seasonal snowpacks to drainage networks. Removal of forest canopy and undergrowth can change the soil moisture regime by decreasing evapotranspiration and eliminating interception of precipitation and radiation. Seasonal and diurnal soil moisture variation are examined along a clearcut and forested hillslope within a high-elevation mixed conifer forest in the Fraser Experimental Forest near Fraser, Colorado, USA. Volumetric soil moisture content was measured on both hillslopes during 53 separate neutron probe surveys starting on April 16, 2001 and ending on June 20, 2001. Prior to complete snow ablation, which occurred on May 14 on both hillslopes, intensive sampling schemes were used to characterize the diurnal variability during early, middle and late melt periods. Followingmelt out, soil moisture was sampled biweekly with the exception of one diurnal sampling period. Volumetric soilmoisture content was generally greater on the clearcut hillslope during the period of observation. Differences inaverage maximum diurnal soil moisture content change between hillslopes were not significant. Both hillslopesshowed a decrease in maximum diurnal soil moisture content change as the melt season progressed and soilmoisture content increased.