Submitted to: Journal of Arid Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2011
Publication Date: 9/1/2011
Citation: Whitford, W.G., Steinberger, Y. 2011. Effects of simulated storm sizes and nitrogen on three Chihuahuan Desert perennial herbs and a grass. Journal of Arid Environments. 75:861-864. Interpretive Summary: Changing climatic patterns in the southwestern United States could impact not only temperature but rainfall patterns. Possible impacts on rainfall include not only amount of rain, but characteristics of storm events. Increasing extreme climatic events could result in patterns such as less total rainfall but infrequent yet, more intense storms. This study used simulated rainfall events to examine responses in plant productivity to different amounts and timing of rainfall. In the Chihuahuan Desert, most rainfall occurs in small events, each well less than ½” of rain. This small study, funded in part by the National Science Foundation, examined plant responses to the same amounts of rainfall but that occurred in either small events of <0.1” compared to intense events of 1” of precipitation. Four different plant species were observed. Two species showed no difference in production between the different simulated storm intensities, one species increased production with the more intense storms, and one species decreased production with the more intense storms. Changing rainfall patterns would likely alter vegetation features in deserts, possibly in ways we can learn to predict.
Technical Abstract: Establishment and growth of three perennial herbs and a small tussock grass were studied in an experiment that provided simulated rainfall of 6 mm week_1 or 25 mm once per month and nitrogen fertilization in combination with the different simulated rainfall regimes. Wild onion, Allium macropetalum, failed to establish in plots receiving 25 mm month_1 simulated rainfall. The perennial composite, Bahia absinthifolia, occurred at higher densities in plots that were not irrigated but there were no differences in biomass in any of the irrigation or fertilization treatments. Desert holly, Perezia nana, failed to establish in nitrogen fertilized plots and developed higher abundance and biomass in plots receiving 25 mm month_1. Nitrogen fertilization had either no effect or an adverse effect on the perennial herbs. The tussock grass, Dasychloa pulchella exhibited highest abundance and biomass with 6 mm week_1 added water plus nitrogen. Since global climate change will affect both rain storm frequency and size and atmospheric nitrogen deposition, the results of this study are applicable to understanding vegetation responses climate change.