How Plants Survive in the Desert: Competing for Water with Climate Change

Many think of deserts as inhospitable landscapes devoid of life. Yet many species have adapted to these harsh conditions as they compete for limited resources. Now, scientists have uncovered the unusual mechanisms that plants use in order to survive the desert environment, revealing how they compete with their neighbors for water.

In deserts, variable weather is common. This means that some years and localities receive lots of rain, while other areas remain dry. This means that plant communities can change 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. In order to investigate this phenomenon a bit further, the researchers looked at the effect that competition and water usage have on plant communities in the Sonoran Desert.

The researchers looked at three widespread and abundant plants that use different strategies to cope in this variable desert environment. They then 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.

What was most interesting, though, was the fact that climate change is impacting these communities. As the environment becomes hotter and drier, plant communities are shifting.

"The Sonoran Desert has already begun to exhibit such changes," said Jennifer Gremer, one of the researchers, in a news release. "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."

So what did the scientists find? All species did better in wet environments when grown alone. However, water availability had addition 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.

The findings reveal a bit more about how these plants compete in certain environments. In addition, they could allow researchers to better map long-term patterns of diversity in the desert ecosystem. This has implications for understanding and predicting responses to climate change.

The findings are published in the American Journal of Botany.