Event Title

Associations of Near-Surface Soil Moisture and Annual Plant Community Dynamics

Location

Eccles Conference Center

Event Website

http://water.usu.edu/

Start Date

4-20-2010 10:10 AM

End Date

4-20-2010 10:15 AM

Description

Many ecosystems have lost native species or functional diversity due to species invasions. When community disassembly is advanced, changes in water resource pool dynamics can provide a resource for establishment of other species. Bromus tectorum (cheatgrass) is an invasive annual dominant in former sagebrush-steppe communities. When cheatgrass experiences mortality post-germination, soil moisture pools in the top 50 cm are incompletely used, possibly increasing the invasion potential. The objective is to assess whether more complete utilization of upper soil moisture by cheatgrass acts to reduce the potential for new invaders. Soil moisture was measured in a cheatgrass stand from 2000-2002 and 2007-2009, when fall cheatgrass mortality was followed by rapid community change to forbs. Soil moisture modeling was used to generate a continuous set of volumetric water contents. Output from this model is linked to a probabilistic model of invasion potential. Cheatgrass biomass, density, and community species composition were measured. Between 2000-2002 and 2007-2009, the cheagrass-dominated system switched to a forb-dominated community. When cheatgrass dominated ground cover (2000, 2002, 2007), the water remaining in the upper soil pool at mid-summer as a percentage of water content at the start of the season was 47.3% (2002) and 54.2% (2007) for the 30 cm layer. When cheatgrass experiences fall mortality, these ratios the following summer are 88.9% (2001) and 94.8% (2008) for the 30 cm layer. Our results show the importance of the interplay between available soil moisture, rapid community change, and invasion potential.

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Apr 20th, 10:10 AM Apr 20th, 10:15 AM

Associations of Near-Surface Soil Moisture and Annual Plant Community Dynamics

Eccles Conference Center

Many ecosystems have lost native species or functional diversity due to species invasions. When community disassembly is advanced, changes in water resource pool dynamics can provide a resource for establishment of other species. Bromus tectorum (cheatgrass) is an invasive annual dominant in former sagebrush-steppe communities. When cheatgrass experiences mortality post-germination, soil moisture pools in the top 50 cm are incompletely used, possibly increasing the invasion potential. The objective is to assess whether more complete utilization of upper soil moisture by cheatgrass acts to reduce the potential for new invaders. Soil moisture was measured in a cheatgrass stand from 2000-2002 and 2007-2009, when fall cheatgrass mortality was followed by rapid community change to forbs. Soil moisture modeling was used to generate a continuous set of volumetric water contents. Output from this model is linked to a probabilistic model of invasion potential. Cheatgrass biomass, density, and community species composition were measured. Between 2000-2002 and 2007-2009, the cheagrass-dominated system switched to a forb-dominated community. When cheatgrass dominated ground cover (2000, 2002, 2007), the water remaining in the upper soil pool at mid-summer as a percentage of water content at the start of the season was 47.3% (2002) and 54.2% (2007) for the 30 cm layer. When cheatgrass experiences fall mortality, these ratios the following summer are 88.9% (2001) and 94.8% (2008) for the 30 cm layer. Our results show the importance of the interplay between available soil moisture, rapid community change, and invasion potential.

https://digitalcommons.usu.edu/runoff/2010/Posters/18