From The University of Arizona (US) via Eos : “Invasive Plants and Climate Change Will Alter Desert Landscapes”

From The University of Arizona (US)

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13 January 2022
Katherine Kornei

In experiments conducted in Biosphere 2 at The University of Arizona (US), invasive buffelgrass weathers higher temperatures and drought conditions better than its native brethren.

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In Arizona’s Saguaro National Park, volunteers remove buffelgrass, an invasive species, from the desert ecosystem. Credit: National Park Service (US).

The towering saguaro cactus may be the icon of the American Southwest, but an invasive plant is steadily encroaching into desert ecosystems. The interloper, a knee-high species of grass known as buffelgrass, will likely become even more of a presence in arid landscapes in the future, new research has revealed. That’s because buffelgrass weathers increased temperatures and drought conditions—two hallmarks of climate change—more readily than its native brethren. According to the researchers, arid environments are slated to experience pronounced changes in vegetation in the coming decades, a shift that will have far-reaching implications not only for desert ecosystems themselves but also for human-built infrastructures.

Guaranteed from the Start

Buffelgrass (Pennisetum ciliare) was first introduced to North America from Africa in the 1930s. The tough grass was originally intended as food for foraging cattle. Like other plants such as kudzu that have thrived in their nonnative environments, buffelgrass’s biological success was just about guaranteed from the start: Its seedlings survive at high rates, it can rapidly colonize bare soil, it makes efficient use of water, and it’s capable of tolerating extreme drought.

Today buffelgrass is a common sight in the vast Sonoran Desert, which spans the southwestern United States and northwestern Mexico. But it’s an unwelcome guest—buffelgrass has been labeled a “noxious weed” by the Arizona Department of Agriculture, and the National Park Service regularly hosts “buffelgrass pulls.”

“It invades deserts and crowds out native plants,” said Perry Grissom, a restoration ecologist at Saguaro National Park in Tucson who was not involved in the research and who has led many buffelgrass pulls. “It’s better adapted to our desert than our plants that are endemic.”

Biodiversity to Monoculture

Buffelgrass’s bad reputation is well earned, said Sujith Ravi, an environmental scientist at Temple University (US), lead author of the study. It slashes ecosystem biodiversity by outcompeting native grasses, leading to landscapes that are veritable monocultures, he said. “Whereas there used to be a mixture of different communities, now it’s more of a single-community landscape.”

That’s bad news, because biodiversity has been shown to make ecosystems more stable and resilient to potentially adverse changes. And when an inevitable “crash” occurs—when essentially all vegetation dies off for a period of time—the soil that’s exposed is readily eroded by wind and water. “There’s an irreversible loss of resources from the system,” explained Ravi. Furthermore, when buffelgrass thrives, the thick vegetation facilitates the spread of fire in an otherwise patchy landscape, and larger fires are more likely to affect human-built infrastructure.

With climate models predicting increasing temperatures and more frequent droughts in arid landscapes, an open question is how well buffelgrass will fare in the future compared with native plants. Several years ago, Ravi and his colleagues began an experimental investigation of buffelgrass and its native counterpart, tanglehead (Heteropogon contortus), in the glass-walled Biosphere 2 research facility in southern Arizona.

A Harbinger of the Future

Biosphere 2 is an ideal laboratory for studying the effects of climate change because it can be tuned to create different environmental conditions. The facility, which tops 3 acres, reproduces several of the planet’s major biomes—including the ocean, wetlands, rain forest, savannah, and desert. “It’s like a field experiment because it’s so huge,” said Ravi.

The team grew hundreds of buffelgrass and tanglehead plants and divided them between Biosphere 2’s savannah biome, maintained at ambient conditions, and its desert biome, which is warmed by roughly 5°C. The idea was to repeat the experiments in two conditions to mimic the effects of climate change, said Ravi.

After watering the plants regularly for a few months, the researchers then withheld irrigation from half of the plants for several months, effectively exposing them to drought-like conditions. The water-starved grasses responded as they would in nature: They went dormant. The team accordingly irrigated the plants again the following spring before finally quantifying what fraction of grasses of each species, exposed to each set of temperature and moisture conditions, survived.

Ravi and his colleagues found that grasses of both species rallied after experiencing drought-like conditions at ambient temperatures. But the combination of warmer temperatures and lack of moisture killed 100% of the native tanglehead plants compared with only roughly 80% of the invasive buffelgrass plants. That’s a significant difference in mortality, said Ravi. “If something is going to come back, it’s going to be the invasive grass.”

This finding wasn’t wholly unexpected given the nature of buffelgrass, said Grissom. “After seeing how it behaves, I’m not surprised. It’s really tough.”

These results are a harbinger of what’s to come in arid regions, the researchers suggested. Drought- and heat-adapted invasive plants like buffelgrass will increasingly gain a toehold, at the expense of native species. Climate change and biological invasions work in tandem to alter desert landscapes for the worse, said Ravi. “They can synergistically act to drive landscapes into degradation.”

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As of 2019, the The University of Arizona (US) enrolled 45,918 students in 19 separate colleges/schools, including The University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). The University of Arizona is one of three universities governed by the Arizona Board of Regents. The university is part of the Association of American Universities and is the only member from Arizona, and also part of the Universities Research Association(US). The university is classified among “R1: Doctoral Universities – Very High Research Activity”.

Known as the Arizona Wildcats (often shortened to “Cats”), The University of Arizona’s intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. The University of Arizona athletes have won national titles in several sports, most notably men’s basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.

After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew. The Arizona Territory’s “Thieving Thirteenth” Legislature approved The University of Arizona in 1885 and selected the city of Tucson to receive the appropriation to build the university. Tucson hoped to receive the appropriation for the territory’s mental hospital, which carried a $100,000 allocation instead of the $25,000 allotted to the territory’s only university (Arizona State University(US) was also chartered in 1885, but it was created as Arizona’s normal school, and not a university). Flooding on the Salt River delayed Tucson’s legislators, and by they time they reached Prescott, back-room deals allocating the most desirable territorial institutions had been made. Tucson was largely disappointed with receiving what was viewed as an inferior prize.

With no parties willing to provide land for the new institution, the citizens of Tucson prepared to return the money to the Territorial Legislature until two gamblers and a saloon keeper decided to donate the land to build the school. Construction of Old Main, the first building on campus, began on October 27, 1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no high schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation.

Research

The University of Arizona is classified among “R1: Doctoral Universities – Very high research activity”. UArizona is the fourth most awarded public university by National Aeronautics and Space Administration(US) for research. The University of Arizona was awarded over $325 million for its Lunar and Planetary Laboratory (LPL) to lead NASA’s 2007–08 mission to Mars to explore the Martian Arctic, and $800 million for its OSIRIS-REx mission, the first in U.S. history to sample an asteroid.

The LPL’s work in the Cassini spacecraft orbit around Saturn is larger than any other university globally. The University of Arizona laboratory designed and operated the atmospheric radiation investigations and imaging on the probe. The University of Arizona operates the HiRISE camera, a part of the Mars Reconnaissance Orbiter. While using the HiRISE camera in 2011, University of Arizona alumnus Lujendra Ojha and his team discovered proof of liquid water on the surface of Mars—a discovery confirmed by NASA in 2015. The University of Arizona receives more NASA grants annually than the next nine top NASA/JPL-Caltech(US)-funded universities combined. As of March 2016, The University of Arizona’s Lunar and Planetary Laboratory is actively involved in ten spacecraft missions: Cassini VIMS; Grail; the HiRISE camera orbiting Mars; the Juno mission orbiting Jupiter; Lunar Reconnaissance Orbiter (LRO); Maven, which will explore Mars’ upper atmosphere and interactions with the sun; Solar Probe Plus, a historic mission into the Sun’s atmosphere for the first time; Rosetta’s VIRTIS; WISE; and OSIRIS-REx, the first U.S. sample-return mission to a near-earth asteroid, which launched on September 8, 2016.

The University of Arizona students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UArizona is among the top 25 producers of Fulbright awards in the U.S.

The University of Arizona is a member of the Association of Universities for Research in Astronomy(US), a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory(US) just outside Tucson. Led by Roger Angel, researchers in the Steward Observatory Mirror Lab at The University of Arizona are working in concert to build the world’s most advanced telescope. Known as the Giant Magellan Telescope(CL), it will produce images 10 times sharper than those from the Earth-orbiting Hubble Telescope.

GMT Giant Magellan Telescope(CL) 21 meters, to be at the Carnegie Institution for Science’s(US) NOIRLab(US) NOAO(US) Las Campanas Observatory(CL), some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.

The telescope is set to be completed in 2021. GMT will ultimately cost $1 billion. Researchers from at least nine institutions are working to secure the funding for the project. The telescope will include seven 18-ton mirrors capable of providing clear images of volcanoes and riverbeds on Mars and mountains on the moon at a rate 40 times faster than the world’s current large telescopes. The mirrors of the Giant Magellan Telescope will be built at The University of Arizona and transported to a permanent mountaintop site in the Chilean Andes where the telescope will be constructed.

Reaching Mars in March 2006, the Mars Reconnaissance Orbiter contained the HiRISE camera, with Principal Investigator Alfred McEwen as the lead on the project. This National Aeronautics and Space Agency (US) mission to Mars carrying the UArizona-designed camera is capturing the highest-resolution images of the planet ever seen. The journey of the orbiter was 300 million miles. In August 2007, The University of Arizona, under the charge of Scientist Peter Smith, led the Phoenix Mars Mission, the first mission completely controlled by a university. Reaching the planet’s surface in May 2008, the mission’s purpose was to improve knowledge of the Martian Arctic. The Arizona Radio Observatory(US), a part of The University of Arizona Department of Astronomy Steward Observatory(US), operates the Submillimeter Telescope on Mount Graham.

The National Science Foundation(US) funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as “CyVerse”, the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines.

In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona, north of Tucson, effective July 1. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.

U Arizona mirror lab-Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

University of Arizona’s Biosphere 2, located in the Sonoran desert. An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why The University of Arizona is a university unlike any other.

University of Arizona Landscape Evolution Observatory at Biosphere 2.