land near Morongo Valley, Calif. But it’s not smugglers or bandits who interest Louis Santiago, the man who watches the victim but yet is powerless to stop the attack. The casualty that Santiago, a UCR botanist, studies on this day is an unassuming yet attractive shrub with red berries and yellowish flowers, the lotebush (Ziziphus parryi) or California crucillo.
This modest plant fights for its very existence in a battlefield that’s changing rapidly due to drought. And Santiago follows this struggle with the passion of a war correspondent.
“Climate change has very local consequences,” explains Santiago. “In Southern California, we’ve experienced increased variability in rainfall (wettest and driest) due to climatic changes. “We need to understand what is happening right here. It’s hard to measure globally because it’s so removed. I’m an advocate of translating the global change to regional change, which is more tangible and something people can get their heads around.”
Santiago’s work, though, takes a novel approach that can yield new information. He doesn’t study how the lack of water affects local plants. He studies how plants affect drought.
Santiago recently received a two-year, $175,000 grant from the National Science Foundation to study how Southern California’s plants influence the region’s drought. He and his team investigate which plant species, like the lotebush, are most susceptible to drought and how their disappearance might impact the amount of water available for human use.
“The lotebush is especially interesting,” explains Santiago, “and especially susceptible to disappearing because, in contrast to most of the other species at the study site that more commonly occur in desert or chaparral ecosystems, lotebush only occurs where these two major vegetation types intersect.”
This means its particular habitat is subject to change and the lotebush may be sensitive to relatively minor alterations in temperature or rainfall.
Every plant has its threshold for hydraulic failure. By studying their functional characteristics, like the rate of photosynthesis, resistance to drought, water potential of the plant and rate of water evaporation, researchers can predict which species will go extinct.
“Even things that seem straightforward and intuitive turn out to be more complicated,” explains graduate student Lee Buckingham, who has worked with Santiago for more than a year, selecting study sites and setting up the lab.
“You think plants that live in a dry environment have to be inherently resistant to drought but we’re learning that’s not always the case.”
Why is this important?
“Plants have a big effect on the water cycle,” says Santiago. “There may be a drought that could cause a coastalaffiliated plant species” — one that requires more water — “to go extinct. This could decrease the amount of water in the aquifer since desert vegetation has very deep roots, which are crucial to feeding underground water supplies and vice versa.”
“By computer-modeling the outcome, we can then predict feedbacks to the water cycle,” says Buckingham. “Our work can help determine how this will shape our water resources.”
This information is especially interesting to the state’s watershed managers.
Southern California residents are more aware of hydrologic services due to living in areas of drought.
Santiago explains that part of his mission is to generate interest among students.
“Water is very alive,” he says. “This is a topic that concerns urban and suburban lifestyles. How are we connected to water? My job is also to help students see how we are linked to the ecosystem.”
Freshman Shakae Kelly, a biological sciences major and one of Santiago’s lab students, assists in monitoring sensors that measure the flow of water in the plants.
“I helped build the models,” she says. “I’m more open to learning about plants and it’s given me more skills in the lab.”
The team has already noticed species migrations.
Some movements are as simple as moving up a slope to a slightly moister climate.
“It’s like moving neighborhoods,” says Santiago.
The project works to identify the species that are really on the edge of the range and susceptible to change.
“It’s an opportunity to get to know the arid California community,” says Santiago, who first became interested in this field while working in Hawaii in tropical cloud forests.
“Those cloud forests produce a lot of water for the island,” he notes. “The relationship between plants and water was so obvious there.”
The same principles apply to California, where water is so vital.
This novel approach to studying plants also helps researchers understand biodiversity in California, where coastal vegetation intermingles with desert flora.
“The intersection of these two vegetation types and how they overlap to create a new community is unique to us in North America,” notes Santiago. “There’s no doubt it’s threatened by climate change. It’s a legacy that could be lost soon.”
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The Watch List
In addition to the lotebush, the following plants are on the watch list.
They face extinction or migration due to climate change.
Sugar bush (Rhus ovata)
Whereabouts: Occurs near the coast or in the coastal mountains and valleys.
Susceptibility: From a lineage that has tropical origins; presence in the desert is especially unexpected.
Mojave indigo bush (Psorothamnus arborescens)
Description: Also called the California dalea, it is a spiny shrub that can grow up to 3 feet tall and has bright violet flowers.
Whereabouts: Primarily in the deserts and
does not occur on the coast. Research sites on the eastern side of the
San Bernardino Mountains represent the western edge of its range.
Susceptibility: Considering the potential for drying trends, this is another species that could move westward.
California buckwheat (Eriogonum fasciculatum)
Description: A low-spreading shrub whose white or pink flowers have a slight fragrance; a magnet for butterflies and bees.
Whereabouts: Although this species mostly occurs along the coast or in coastal mountains and valleys, it’s actually of desert origin.
Susceptibility: Has shifted its range relatively recently and, unlike other local species, can expand its range if climate change involves increased drought.