Effect of canopy removal on snowpack quantity and quality, Fraser experimental forest, Colorado

Snowpack peak water equivalent (PWE), ion concentration, content, and spati al distribution of ion load data from spring 1987-1996 in a 1 ha clearcut a nd adjacent forested plots vegetated by mature Picea engelmannii and Abies lasiocarpa in the Fraser experimental forest (FEF), Colorado are presented. Our objectives were: (1) to see if a forest opening might redistribute sno wfall, snowpack moisture, and snowpack chemical content, and (2) to examine the importance of canopy interception on snowpack quantity and chemistry. On an average, the canopy intercepted 36% of snowfall. Interception was cor related with snowfall amount, snowpack PWE beneath the canopy, and air temp erature. Canopy removal increased snowpack PWE to >90% cumulative snowfall inputs. Snowpack K+, H+, and NH4+ concentrations on the clearcut were lower and NO3- higher than in the snowpack beneath the forested plots. Cumulativ e snowfall K+ input was less than in the clearcut snowpack; H+ inputs were greater in snowfall than in the snowpack of any plot; and inorganic N (NO3- and NH4+) inputs from snowfall to the clearcut were greater than to the fo rested plots. Processes accounting for the differences between snowfall inp uts and snowpack ion content were leaching of organic debris in the snowpac k, differential elution of the snowpack, and canopy retention. There were s ignificant trends by year in snowpack ion content at PWE without similar tr ends in snowfall inputs. This finding coupled with snowpack ion elution bri ng into question the use of snowpack chemistry as an indicator of winter at mospheric inputs in short-term studies. (C) 2001 Elsevier Science B.V. All rights reserved.