With dwindling water supplies, the timing of rainfall matters

Date:
April 18, 2022
Source:
University of California - Riverside
Summary:
A new study shows it's not how much extra water you give your
plants, but when you give it that counts. Researchers observed that
in summer, plants grow more when given extra water, in addition
to any natural rainfall.

However, the same is not true in winter.



FULL STORY ==========================================================================
A new UC Riverside study shows it's not how much extra water you give
your plants, but when you give it that counts.


==========================================================================
This is especially true near Palm Springs, where the research team created artificial rainfall to examine the effects on plants over the course
of two years. This region has both winter and summer growing seasons,
both of which are increasingly impacted by drought and, occasionally,
extreme rain events.

Normally, some desert wildflowers and grasses begin growing in December,
and are dead by June. A second community of plants sprouts in July
and flowers in August. These include the wildflowers that make for an
extremely popular tourist attraction in "super bloom" years.

"We wanted to understand whether one season is more sensitive to climate
change than another," said Marko Spasojevic, UCR plant ecologist and
lead study author. "If we see an increase or decrease in summer rains,
or winter rains, how does that affect the ecosystem?" The team observed
that in summer, plants grow more when given extra water, in addition to
any natural rainfall. However, the same was not true in winter.

"Essentially, adding water in summer gets us more bang for our buck," Spasojevic said.



========================================================================== Their findings are described in a paper published in the University of California journal Elementa.

Over the course of the study, the team observed 24 plots of land at the
Boyd Deep Canyon Desert Research Center, in the Palm Desert area. Some
of the plots got whatever rain naturally fell. Others were covered
and allowed to receive rain only in one season. A third group of plots
received additional collected rainwater.

While adding water in summer resulted in higher plant biomass, it
generally did not increase the diversity of plants that grew, the
researchers noted.

Decreasing rainfall, in contrast, had negative effects on plants across
both summer and winter, but may lead to some increased growth in the
following off- seasons.

Implications of the work extend beyond learning when additional water
resources might be applied simply to help plants grow. Whole communities
of animals depend on these plants. They are critical for pollinators
such as bees and butterflies, and they play a big role in controlling
erosion and movement of soils by wind.

"Studies like this one are critical for understanding the complex effects
of climate change to dryland ecosystems," said Darrel Jenerette, UCR
landscape ecologist and study co-author.

Desert plants also play an important role in removing carbon dioxide and nitrogen from the atmosphere to use as fuel for growth. Microbes that
live in the soil can use the carbon and nitrogen released by plant roots,
then send it back into the atmosphere where it can affect the climate.

"Drylands cover roughly a third of the land surface, so even small
changes in the way they take in and emit carbon or nitrogen could have
a big impact on our atmosphere," said Peter Homyak, UCR environmental
scientist and study co- author.

As the team continues this research over the next few years, they expect
to see changes in soil carbon and nitrogen cycling, given that plants
are already being affected by changes in seasonal rainfall, as this
study shows.

"Can changes in precipitation patterns alter the feedback between plants
and microbes, destabilizing the carbon locked in soils and sending more of
it into the atmosphere? We are working on figuring that out," Homyak said.


========================================================================== Story Source: Materials provided by
University_of_California_-_Riverside. Original written by Jules
Bernstein. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Marko J. Spasojevic, Peter M. Homyak, G. Darrel Jenerette, Mike L.

Goulden, Shane McFaul, Tesa Madsen-McQueen, Lisa Schauer, Miguel
Solis.

Altered precipitation has asymmetric impacts on annual plant
communities in warm and cool growing seasons. Elementa: Science
of the Anthropocene, 2022; 10 (1) DOI: 10.1525/elementa.2021.00014 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/04/220418085656.htm

--- up 7 weeks, 10 hours, 51 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)