Event Title

Effects of Plant Functional Type and Interannual Precipitation Variability on Long-Term Soil Moisture Resource Pool Trends

Presenter Information

Scott Jones

Location

ECC 201/203 & 205/207

Event Website

https://water.usu.edu/htm/conference/2013conference

Start Date

9-4-2013 5:15 PM

End Date

9-4-2013 5:25 PM

Description

Interannual fluctuations in resource availability, as mediated through variations in over-winter precipitation amounts and summer storms, may have an important effect in determining how the soil water resources vary under differing vegetation types. Water is supplied to the vegetation in two pools—a shallower growth pool restricted to the top 50 cm supplying water and used early in the growing season; and a maintenance pool of deeper water tapped to supply the transpiration demands of the warmest part of the year (Ryel et al, 2010). Four dominant Great Basin species exhibit differences in soil moisture trends based on two years of measured data. Cheatgrass (Bromus tectorum) utilizes water stored in the top 50 cm of the profile before senescing in late spring and juniper (Juniperus osteosperma) depletes water stored in the top 50 cm of the soil, while deeper layers remain at relatively high water potential (Ryel et al, 2010). Crested wheatgrass (Agropyron desertorum) and sagebrush (Artemisia tridentata) draw down the soil moisture to moderately low water potentials to depths of 1.5 m (Ryel et al, 2010). Soil water resources under crested wheatgrass and sagebrush are possibly more variable from year to year due in part to these plants’ ability to extract most of the water from the rooting zone, leaving little in the profile as a buffer against years of low precipitation. Inverse numerical simulations provide estimates of soil hydraulic parameters under each of these vegetation types. Using the fitted hydraulic parameters, climate data (1954-2012), and measured and estimated plant physiological characteristics, trends in the duration of soil moisture pools can be simulated. For simulations, the numerical and boundary modeling tools in HYDRUS-1D are used under bare soil and four different plant functional types including an annual grass, perennial grass, semi-drought deciduous shrub, and evergreen tree. The project has basic and applied ecological applications to how plants influence the interannual accumulation and use of water in the growth and maintenance pools in the sagebrush-steppe. Ryel, RJ, AJ Leffler, C Ivans, MS Peek, and MM Caldwell. 2010. Functional differences in water use patterns of contrasting life forms in Great Basin steppelands. Vad. Zone J. 9:548-560.

 
Apr 9th, 5:15 PM Apr 9th, 5:25 PM

Effects of Plant Functional Type and Interannual Precipitation Variability on Long-Term Soil Moisture Resource Pool Trends

ECC 201/203 & 205/207

Interannual fluctuations in resource availability, as mediated through variations in over-winter precipitation amounts and summer storms, may have an important effect in determining how the soil water resources vary under differing vegetation types. Water is supplied to the vegetation in two pools—a shallower growth pool restricted to the top 50 cm supplying water and used early in the growing season; and a maintenance pool of deeper water tapped to supply the transpiration demands of the warmest part of the year (Ryel et al, 2010). Four dominant Great Basin species exhibit differences in soil moisture trends based on two years of measured data. Cheatgrass (Bromus tectorum) utilizes water stored in the top 50 cm of the profile before senescing in late spring and juniper (Juniperus osteosperma) depletes water stored in the top 50 cm of the soil, while deeper layers remain at relatively high water potential (Ryel et al, 2010). Crested wheatgrass (Agropyron desertorum) and sagebrush (Artemisia tridentata) draw down the soil moisture to moderately low water potentials to depths of 1.5 m (Ryel et al, 2010). Soil water resources under crested wheatgrass and sagebrush are possibly more variable from year to year due in part to these plants’ ability to extract most of the water from the rooting zone, leaving little in the profile as a buffer against years of low precipitation. Inverse numerical simulations provide estimates of soil hydraulic parameters under each of these vegetation types. Using the fitted hydraulic parameters, climate data (1954-2012), and measured and estimated plant physiological characteristics, trends in the duration of soil moisture pools can be simulated. For simulations, the numerical and boundary modeling tools in HYDRUS-1D are used under bare soil and four different plant functional types including an annual grass, perennial grass, semi-drought deciduous shrub, and evergreen tree. The project has basic and applied ecological applications to how plants influence the interannual accumulation and use of water in the growth and maintenance pools in the sagebrush-steppe. Ryel, RJ, AJ Leffler, C Ivans, MS Peek, and MM Caldwell. 2010. Functional differences in water use patterns of contrasting life forms in Great Basin steppelands. Vad. Zone J. 9:548-560.

http://digitalcommons.usu.edu/runoff/2013/AllPosters/12