Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/26/2014
Publication Date: 3/1/2014
Publication URL: http://handle.nal.usda.gov/10113/58779
Citation: Bansal, S., James, J., Sheley, R.L. 2014. The effects of precipitation and soil type on three invasive annual grasses in the western United States. Journal of Arid Environments. 104:38-42. Interpretive Summary: Multiple species of annual grasses are invading sagebrush-steppe communities throughout the western United States. Most research has focused on dominant species such as Bromus tectorum (cheatgrass), yet other, less studied annual grasses such as Taeniatherum caput-medusae (medusahead) and Ventenata dubia (ventenata) are spreading rapidly. Predicted changes in precipitation regimes with climate change may interact with soil properties such as texture to create a gradient of soil moisture availability, which may favor some invasives over others. We conducted a full factorial study examining the effects of two watering regimes (small/frequent, large/infrequent rain pulses) across nine soil types on the growth of cheatgrass, medusahead and ventenata. The two watering regimes had relatively strong effects on soil water content, but generally did not impact plant growth. The primary exception was greater root growth of medusahead in response to the large/infrequent watering treatment. Variation in soil properties had relatively greater influence on plant growth compared to the watering treatments. Our findings reveal that these three invasive grasses generally respond similarly to changes in precipitation regimes and to edaphic factors.
Technical Abstract: Sagebrush-steppe ecosystems in the Great Basin are highly susceptible to annual grass invasion. Large regions are covered by Bromus tectorum (cheatgrass), but there has been a recent upsurge in the abundance and distribution of Taeniatherum caput-medusae (medusahead) and Ventenata dubia (ventenata). Relatively little is known about the responses of medusahead and ventenata to the environment, such as to precipitation regimes or soil types. We performed a growth chamber study to assess if medusahead or ventenata have superior plant performance compared to cheatgrass under a less frequent precipitation regime that is expected in the future across a range of soil types. We found only medusahead responded positively to the large and infrequent rain pulses, while all the species responded similarly and strongly to soil types. In general, annual grasses generally respond similarly to precipitation and edaphic factors.