Coping in a harsh desert environment
Far from being devoid of life, deserts are home to numerous plants and animals. In the desert, plants and animals often compete for limited resources, especially water. To cope, plants will adopt different strategies to compete with their neighbors for this precious resource.
In natural environments, water availability is often stochastic—some years and localities receive lots of rain, while other areas and times remain dry. During dry years, plants that are more efficient with water use often are the most successful. But with success comes a trade-off; in wetter years, these efficient plants may struggle against faster-growing plants.
For deserts, variable weather yields change in plant community patterns between wet and dry years, with high densities and a diversity of plants in wet years, and a reduction in both quantity and number of species in dry years. This effect, competition and water usage was investigated in the Sonoran Desert by University of Arizona researchers led by Jennifer Gremer and published in the American Journal of Botany.
Gremer and her team looked at three widespread and abundant plants native to the Sonoran Desert that use different strategies to cope in this variable desert environment by occupying different positions on a trade-off spectrum between relative growth rate and water use efficiency. They interpreted how well plants responded to different conditions, such as high and low water availability and competition, by measuring plant biomass of shoots, stems, and roots.
With the onset of climate change, the deserts are getting hotter and drier, and have been a focus of global change models. "The Sonoran Desert has already begun to exhibit such changes," explains Gremer. "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."
The research showed that all species did better in wet environments when grown alone; however, water availability had additional effects when competition was included. Species that have faster growth rates were less affected by competition in wet environments, whereas those 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," explains Gremer. In most settings of this research, though, the intermediate species had the largest competitive effect of all species.
Read more at the American Journal of Botany.
Desert image via Shutterstock.