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.
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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.