Event Title

Differential snowpack accumulation and water dynamics in aspen and conifer communities: implications for water yield and function

Presenter Information

Eric Martin LaMalfa

Location

ECC 216

Event Website

http://water.usu.edu/htm/conference/past-spring-runoff-conferences

Start Date

5-4-2007 6:10 PM

End Date

5-4-2007 6:15 PM

Description

Early succession aspen and late succession conifer forests have different architecture and physiology affecting hydrologic transfer processes. An evaluation of water pools and fluxes was used to determine differences in the hydrologic dynamics between stands of quaking aspen (Populus tremuloides) and associated stands of mixed conifer consisting of white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii) and Engelmann spruce (Picea engelmannii). In 2005 and 2006, measurements of snow water accumulation (SWE), snow ablation (melt), soil water content, snowpack sublimation, and evapotranspiration (ET) were measured in adjacent aspen and conifer stands. Peak (snow water equivalent) SWE averaged 34 to 44% higher in aspen in 2005 (average snow pack) and 2006 (above average snowpack), respectively, while snow ablation rates were greater in aspen stands (21 mm day-1) compared to conifer stands (11 mm day-1). When changes in soil water content (due to over winter snowmelt) were combined with peak snow accumulation in 2006, aspen had greater potential (42-83%) water yield for runoff and groundwater recharge. Snowpack sublimation during the ablation period was not significantly different between meadow, aspen, and conifer sites and comprised <5% of the winter precipitation. Extended conifer transpiration in spring and fall did not contribute to large differences in water yield (<28 mm yr-1). Summertime ET rates were higher aspen (3.6 mm day-1) than in conifer (2.7 mm day-1), and net ET largely reflected soil column porosity. This study shows that the largest differences in annual water yield between aspen and conifer stands result from differences in SWE and net summertime ET. Although SWE and accumulation of water in soil was greater in aspen, it was partly offset by greater net annual ET losses in aspen.

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Apr 5th, 6:10 PM Apr 5th, 6:15 PM

Differential snowpack accumulation and water dynamics in aspen and conifer communities: implications for water yield and function

ECC 216

Early succession aspen and late succession conifer forests have different architecture and physiology affecting hydrologic transfer processes. An evaluation of water pools and fluxes was used to determine differences in the hydrologic dynamics between stands of quaking aspen (Populus tremuloides) and associated stands of mixed conifer consisting of white fir (Abies concolor), Douglas-fir (Pseudotsuga menziesii) and Engelmann spruce (Picea engelmannii). In 2005 and 2006, measurements of snow water accumulation (SWE), snow ablation (melt), soil water content, snowpack sublimation, and evapotranspiration (ET) were measured in adjacent aspen and conifer stands. Peak (snow water equivalent) SWE averaged 34 to 44% higher in aspen in 2005 (average snow pack) and 2006 (above average snowpack), respectively, while snow ablation rates were greater in aspen stands (21 mm day-1) compared to conifer stands (11 mm day-1). When changes in soil water content (due to over winter snowmelt) were combined with peak snow accumulation in 2006, aspen had greater potential (42-83%) water yield for runoff and groundwater recharge. Snowpack sublimation during the ablation period was not significantly different between meadow, aspen, and conifer sites and comprised <5% of the winter precipitation. Extended conifer transpiration in spring and fall did not contribute to large differences in water yield (<28 mm yr-1). Summertime ET rates were higher aspen (3.6 mm day-1) than in conifer (2.7 mm day-1), and net ET largely reflected soil column porosity. This study shows that the largest differences in annual water yield between aspen and conifer stands result from differences in SWE and net summertime ET. Although SWE and accumulation of water in soil was greater in aspen, it was partly offset by greater net annual ET losses in aspen.

http://digitalcommons.usu.edu/runoff/2007/AllPosters/11