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Global change effects on Bromus tectorum L. (Poaceae) at its high-elevation range margin
Amy L Concilio1, Michael E Loik, Jayne Belnap
1Department of Environmental Studies, University of California, Santa Cruz, CA 95064, USA. amyconcilio@gmail.com
Global Change Biology
|March 19, 2013
Summary
Global change may expand invasive Bromus tectorum (cheatgrass) at high elevations. Shifts from snow to rain, coupled with nitrogen deposition, could facilitate cheatgrass spread, especially in intershrub areas.
Area of Science:
- Ecology
- Invasive Species Biology
- Climate Change Impacts
Background:
- Global change impacts invasive species distribution at range margins.
- Bromus tectorum (cheatgrass) is an invasive annual grass with minimal impact in the eastern Sierra Nevada, California.
- Understanding cheatgrass response to climate change and nitrogen deposition is crucial for predicting its spread.
Purpose of the Study:
- To determine how Bromus tectorum responds to simulated climate change (snowpack, precipitation) and nitrogen deposition at its high-elevation range margin.
- To assess the influence of shrub cover and intershrub spaces on cheatgrass response.
- To investigate nutrient and water limitations on cheatgrass growth and reproduction.
Main Methods:
- In situ field manipulations over three years in the eastern Sierra Nevada.
- Use of snow fences to alter snowpack depth.
- Irrigation to simulate increased springtime precipitation and nitrogen addition at three levels (0, 5, 10 g m⁻²).
Main Results:
- Deeper snowpack reduced seedling density but not final biomass or spikelet production.
- Increased spring rain events enhanced cheatgrass biomass and spikelet production in intershrub (INTR) plots.
- Cheatgrass was co-limited by nitrogen and water, with rain frequency being more influential than magnitude.
Conclusions:
- Predicted shifts from snow to rain could facilitate Bromus tectorum expansion at high elevations.
- Nitrogen deposition and the timing of rain events are key factors influencing cheatgrass spread.
- Phosphorus limitation may also play a role in cheatgrass expansion, potentially alleviated by nitrogen additions.
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