The Impact of Climate-Driven Phenological Shifts on Cheatgrass in Western North America
Climate change-induced warming can alter plant phenology and disrupt ecosystems like the sagebrush steppe in western North America. The invasive annual grass cheatgrass can thrive under these altered conditions, exacerbating wildfires and threatening wildlife habitat, carbon storage, and other important ecosystem services. We are studying how different densities of cheatgrass respond to increased soil temperatures to better understand climate-driven phenological shifts in the sagebrush steppe.
Background
Plant phenology is the study of the timing of recurring biological events in the lifecycle of plants, such as leaf emergence, flowering, and death. Climate change is leading to warmer air and soil temperatures and altering plant phenology. Shifts in phenology can disrupt plant communities, giving invasive species that are better adapted to warm temperatures a chance to outcompete native plants.
In western North America’s sagebrush steppe, the spread of cheatgrass, a highly flammable invasive-annual grass that originated in Eurasia, has resulted in more frequent and intense fires. The cheatgrass-fire cycle has led to decreased plant and wildlife diversity and changes in the cycling of nutrients and water in the soil. As soil and air temperatures continue to warm, cheatgrass may further expand and thrive. Research into how climate change could impact the spread of cheatgrass could help land managers prepare for the future and implement strategies to control invasion.
The Fire, Invasion, and Ecology in Sagebrush Steppe (FIREss) team conducted a common garden experiment in partnership with Utah State University and the U.S. Department of Agriculture’s Agricultural Research Service to study the impact of warmer soil temperatures on approximately 100 genotypes of cheatgrass. Common gardens are experiments in which plants of the same species are collected from different geographic locations and grown under the same conditions. This approach helps researchers determine if differences in growth and phenology are due to genetics or environmental conditions.
We set up plots and covered them in either black gravel, white gravel, or no gravel. Gravel color changes the soil surface temperature by altering the albedo --a measure of how much light is reflected by a surface. White gravel has a high albedo, meaning it is very reflective and has a cool surface, while black gravel has a lower albedo and absorbs more light, creating a warmer surface. This experiment was designed to improve our understanding of how cheatgrass as a species may react to increased temperatures and adapt to potential future climate conditions. We are also investigating soil microclimate, or the climate conditions at the soil surface, which varies depending on the surrounding or overlying vegetation. We addressed this question by seeding cheatgrass at different densities.
Objectives
- Evaluate the effects of altered soil albedo and seeding density on soil microclimate
- Quantify the impact any differences in microclimate had on cheatgrass growth and cheatgrass plant fitness
Published Results
We conducted a pilot study at experimental sites near Boise, ID and Cheyenne, WY from October-July 2020-2021. Each site included high density seeded plots with 1 cm spacing between cheatgrass seeds, and low-density plots, where cheatgrass was seeded 10 cm apart from another. We set up trail cameras to take pictures every day at 11am, noon, and 1pm to monitor the plants phenology. There was a significant difference in soil temperature between black and white gravel plots. Black gravel plots were an average of 2.6 degrees Celsius warmer at the Boise site and 1.6 degrees Celsius warmer at the Cheyenne site. Overall, this extended the growing season by approximately one month, and led to earlier cheatgrass germination and a 2.8-fold increase in height. We also found that higher density seeding led to taller plants at black gravel plots at both sites. These results suggest that when cheatgrass grows closer together, rather than increasing competition, the plants may provide shade for one another and for the surface, preventing evaporation of soil water and improving growing conditions for the plants.
Visit our team page to learn more about our research.
Plant-Soil-Environment Laboratory (FRESC)
Climate change-induced warming can alter plant phenology and disrupt ecosystems like the sagebrush steppe in western North America. The invasive annual grass cheatgrass can thrive under these altered conditions, exacerbating wildfires and threatening wildlife habitat, carbon storage, and other important ecosystem services. We are studying how different densities of cheatgrass respond to increased soil temperatures to better understand climate-driven phenological shifts in the sagebrush steppe.
Background
Plant phenology is the study of the timing of recurring biological events in the lifecycle of plants, such as leaf emergence, flowering, and death. Climate change is leading to warmer air and soil temperatures and altering plant phenology. Shifts in phenology can disrupt plant communities, giving invasive species that are better adapted to warm temperatures a chance to outcompete native plants.
In western North America’s sagebrush steppe, the spread of cheatgrass, a highly flammable invasive-annual grass that originated in Eurasia, has resulted in more frequent and intense fires. The cheatgrass-fire cycle has led to decreased plant and wildlife diversity and changes in the cycling of nutrients and water in the soil. As soil and air temperatures continue to warm, cheatgrass may further expand and thrive. Research into how climate change could impact the spread of cheatgrass could help land managers prepare for the future and implement strategies to control invasion.
The Fire, Invasion, and Ecology in Sagebrush Steppe (FIREss) team conducted a common garden experiment in partnership with Utah State University and the U.S. Department of Agriculture’s Agricultural Research Service to study the impact of warmer soil temperatures on approximately 100 genotypes of cheatgrass. Common gardens are experiments in which plants of the same species are collected from different geographic locations and grown under the same conditions. This approach helps researchers determine if differences in growth and phenology are due to genetics or environmental conditions.
We set up plots and covered them in either black gravel, white gravel, or no gravel. Gravel color changes the soil surface temperature by altering the albedo --a measure of how much light is reflected by a surface. White gravel has a high albedo, meaning it is very reflective and has a cool surface, while black gravel has a lower albedo and absorbs more light, creating a warmer surface. This experiment was designed to improve our understanding of how cheatgrass as a species may react to increased temperatures and adapt to potential future climate conditions. We are also investigating soil microclimate, or the climate conditions at the soil surface, which varies depending on the surrounding or overlying vegetation. We addressed this question by seeding cheatgrass at different densities.
Objectives
- Evaluate the effects of altered soil albedo and seeding density on soil microclimate
- Quantify the impact any differences in microclimate had on cheatgrass growth and cheatgrass plant fitness
Published Results
We conducted a pilot study at experimental sites near Boise, ID and Cheyenne, WY from October-July 2020-2021. Each site included high density seeded plots with 1 cm spacing between cheatgrass seeds, and low-density plots, where cheatgrass was seeded 10 cm apart from another. We set up trail cameras to take pictures every day at 11am, noon, and 1pm to monitor the plants phenology. There was a significant difference in soil temperature between black and white gravel plots. Black gravel plots were an average of 2.6 degrees Celsius warmer at the Boise site and 1.6 degrees Celsius warmer at the Cheyenne site. Overall, this extended the growing season by approximately one month, and led to earlier cheatgrass germination and a 2.8-fold increase in height. We also found that higher density seeding led to taller plants at black gravel plots at both sites. These results suggest that when cheatgrass grows closer together, rather than increasing competition, the plants may provide shade for one another and for the surface, preventing evaporation of soil water and improving growing conditions for the plants.
Visit our team page to learn more about our research.