New Study Assesses Resource Competition Among Desert Plants

Some species of desert plants fair better if their natural rate of growth is quicker than surrounding plants competing for the same resources, according to new research from a team of botanists working in the Sonoran Desert.

The University of Arizona research team studied three common plants in the Sonoran Desert, which covers a large portion of the southwestern United States in California and Arizona. The team studied two important variables in desert plant communities - water usage and competition.

The research, which is published in the American Journal of Botany, highlights how a warming climate affects desert plant life.

Around the world, deserts are getting hotter and drier, said Jennifer Gremer, who led the research. "The Sonoran Desert has already begun to exhibit such changes," she said. "Specifically, the composition of plant communities has changed over the last 30 years, with species that have high water-use efficiency becoming more common and species with high relative growth rates declining."

Gremer and her colleagues' research revealed that all the plant species studied did better in wet environments when grown alone. But when competition by other plants is introduced, the results differed. The species with faster growth rates were less affected by the competition in wet environments, and plants more efficient with water were less affected in dry environments.

"These observed effects explain the patterns seen in long-term data and are counterintuitive to many readers because some plants might actually do better when conditions are not optimal," Gremer said.

"We need to understand the role of competition and water availability in long-term patterns of diversity in our system," Gremer added. "This has implications for understanding responses to climate change and predicting what these communities will look like in the future."