UCNRS

Sheltering California’s most vulnerable plants

Anonymous — Thu, 19 Dec 2019 06:19:49 +0000

Sheltering California’s most vulnerable plants Anonymous (not verified) Wed, 12/18/2019 - 22:19 More News Kathleen Wong | UC Natural Reserve System May 14, 2019

Monterey larkspur. Pluman ivesia. Hoover’s manzanita. Payson’s jewelflower. Never heard of them? Few others have, either. They’re among California’s most vulnerable plants—rare, found in just a few spots, or extra finicky about where they will grow.

Lucky for them, these and about 370 other vulnerable native plant species are found within the UC Natural Reserve System (NRS). An expansive new study finds the NRS is key to protecting the Golden State's most vulnerable plants now and in the future. While the analysis predicts climate change will have a searing effect on plant conservation across California, the expertise of NRS scientists and other land managers can help shelter these jewels of biodiversity against extinction.

To biologists, vulnerable plants are canaries in the coal mine of climate change. Limited to certain soils or weather conditions, few in number because they have specialized habitat requirements or have been uprooted by California’s large human population, these rarities will be among the most challenging to preserve over the long run.

The number of California rare plant species historically found at each NRS reserve. Image credit: Riordan and Rundel, 2019

The complications of climate change

"The concern is with climate change, plants with more restricted ranges have narrower climatic tolerances and therefore may be more prone to habitat loss or local extinctions," says lead author Erin Riordan. Riordan conducted the research as a postdoctoral scholar at the University of California, Los Angeles.

Some 5,300 plant species are native to California—more than any other state. About a third are considered rare, threatened, or endangered by the California Native Plant Society.

Sensitive plants "make up so much of our biodiversity, that if they're not doing well, we'll be losing a lot," Riordan says.

Riordan used sophisticated climate models to determine whether sensitive plants currently found at NRS reserves are likely to survive there in the future. She came to this work after completing her PhD at UC Los Angeles. For her dissertation, she modeled how climate change will affect the plants of southern California's coastal sage scrub.

Suitable habitat for the Catalina mariposa lily: a) current b) predicted future. Image credit: Riordan and Rundel, 2019

"I wanted my research to have applications for conservation," Riordan says. "So when the opportunity to work with the reserve system came up, I thought this would be a great way to do this type of modeling in a way that could make a difference."

Protected lands such as the 39 reserves in the NRS are major bulwarks of conservation. Its wild landscapes ensure that native plants and animals will continue to find the open space they need to survive. Reserves include examples of most of California's major habitat types.

Safeguarding biodiversity

"As a microcosm of the state's ecological diversity, the NRS is a good surrogate for how sensitive plants will fare across the entire state," says Peggy Fiedler, executive director of the NRS. "This study shows not only how well the NRS safeguards plant biodiversity but also how land managers across California can cooperate to protect vulnerable species going forward."

Riordan began her study by identifying the sensitive plants located at reserves. She consulted reserve plant lists as well as location data from herbarium collections.

"The NRS pulls higher than its weight class in terms of protecting more rare plants than expected," Riordan says.

A statewide refuge

While the NRS covers less than one percent of California's land area, at least 16 percent of sensitive native plants, or 373 species, are found within its 756,000 acres. If anything, these numbers are likely an underestimate. Plant lists are often incomplete and surveys only find species that have sprouted in a given year.

"This finding underscores just how important the NRS is for conservation," Fiedler says. "We choose reserve sites in part for the significance of their habitats. These statistics demonstrate our reserves have been extremely effective at sheltering California's native plant species."

Furthermore, Riordan found, upwards of 70 percent of California's sensitive plant species have been recorded within 50 km (31 miles) of an NRS reserve or associated parks such as Yosemite.

The Santa Catalina mariposa lily faces an uncertain future. Models predict it could lose between 6-100 percent of its current suitable habitat in the Channel Islands and southern California, and may need to move completely out of its current range to survive. Image credit: Noah Elhardt

What the models say

Riordan then used five different climate change scenarios to project what climate at reserves will look like by the end of the 21st century. Reserves in the Sierra Nevada and eastern California will warm far more than those along the coast.

How much rain and snow will fall is even more uncertain; predictions include both increased precipitation and increased drought. Overall, northern and central reserves may get wetter, while southern reserves may get drier. Even so, rising temperatures will increase the drought stress experienced by plants across the NRS.

Riordan modeled how well several different NRS reserves will retain their current portfolio of vulnerable plants. This analysis of the NRS's McLaughlin Natural Reserve (outlined in black), which has many plants found only on serpentine soils, predicts the reserve will lose 50-80 percent of its current vulnerable plant species by 2099. Image credit: Riordan and Rundel, 2019

Riordan wanted to know how many sensitive plants now found within the NRS would need to relocate out of the system to find their growing conditions by 2100. She compared the moisture and temperature requirements for 180 sample species against where those climate conditions will be in the future.

This is where the study's findings got grim. Riordan found that more than half of these species would lose most of their habitat if they couldn't move beyond reserve boundaries.

"That right there is a conservation and resource management challenge," Riordan says.

Riordan went on to evaluate how well six reserves representing a variety of locales and climates were able to retain their vulnerable plants. She found that under future climate scenarios, these reserves retained suitable habitat for less than half of sensitive plant species.

The migration dilemma

One solution is for plants to migrate. And indeed, the outcomes got rosier when Riordan assumed species could migrate to newly suitable habitat within the reserve system and adjacent protected lands such as Anza-Borrego Desert State Park.

But migration isn’t the quick fix it might seem. Genetic traits such as drought, heat, and cold resistance, as well as the availability and quality of newly suitable habitat, affect whether a species will be able to thrive in new environs.

Hoover's manzanita (Arctostaphylus hooveri), found from Monterey Bay to Big Sur, is likely to lose all of its currently suitable habitat with projected climate change. Even if it is able to disperse, models predict that at best its range will shrink by 87%. Image credit: Susan McDougall

Whether plants can reach suitable new sites is another question. Humans can certainly transplant specimens or carry seeds to new sites. Whether people should carry out such assisted migrations, however, is debatable.

“If we humans move plants too fast, too soon, we could disrupt the important local adaptation and genetic diversity that populations need to respond to changing conditions on their own. Or we could create populations no longer adapted to the current climate,” Riordan says.

Uncertainty about what future climate will look like at a given place complicates matters further. People could easily miscalculate and move plants to inappropriate new homes.

The knowledge of NRS staff such as Jim Andre and Tasha La Doux. expert botanists and the directors of Sweeney Granite Mountains Desert Research Center, will help conserve plant species at risk in California. Image credit: Lobsang Wangdu

Collaborating for conservation

The NRS will be key to ensuring vulnerable plants persist into the future. For example, many reserves have long histories of scientific observations. Current reserve staff also tend to have a good sense of how species on their sites are faring.

"There's a wealth of institutional knowledge at reserves," Riordan says. "Our best strategies will incorporate tools like modeling with information from active scientific research and knowledge of that particular location," Riordan says.

In addition, many reserves are located next to large open spaces, and have strong relationships with other land management agencies. These connections help agencies, scientists, and other stakeholders work together to manage species at risk.

"There's a lot of room to develop management strategies to help ensure some of these really negative predictions are not what we wind up with," Riordan says. "The quicker we can work together to create these connected landscapes, the better shot we have at maintaining biodiversity and the important ecosystem services all of us rely on.”

2019-20 Mathias Graduate Student Research Grant awards

Anonymous — Thu, 19 Dec 2019 05:56:51 +0000

2019-20 Mathias Graduate Student Research Grant awards Anonymous (not verified) Wed, 12/18/2019 - 21:56 More News Kathleen Wong | UC Natural Reserve System December 09, 2019

The 2019-20 Mathias Graduate Student Research Grant awards will help 18 students from seven UC campuses conduct field studies at NRS reserves.

These are the four UCR grant recipients:

UC Riverside CNAS grant recipients 2019-2020:

Matthew Green	Sierra Nevada Aquatics Research Lab	Landscape Biodiversity in Alpine Lake-Stream Networks	UC Riverside	2019-2020
Elijah Hall	White Mountain Research Center	Phenology and community composition determine reproductive success through the lens of pollination services	UC Riverside	2019-2020
Christopher Cosma	Boyd Deep Canyon DRC	Linking plant-plant and plant-pollinator interactions along an elevational gradient	UC Riverside	2019-2020
Kathy Pham	White Mountain Research Center	Effects of high-altitude exposure on inflammation and immune phenotypes	UC Riverside	2019-2020

UC NRS -- Joshua trees will be under the gun in the California of the future. Scientists predict that it’ll become too hot and dry for these striking Mojave plants to persist in much its the high desert habitat by 2100. How much water these treelike yucca plants can store at one time is key to their conservation. Daniel Hastings of UC Santa Cruz plans to find the answer with his graduate research at the NRS’s Burns Piñon Ridge Reserve.

This field study, and that of seventeen other University of California graduate students, will be supported by funding from the UC Natural Reserve System’s 2019–20 Mildred E. Mathias Graduate Student Research Grant Program. This year’s recipients come from seven different UC campuses and will pursue their graduate research at a whopping 21 different reserves. Each student will receive up to $3000 to defray the costs of transportation, equipment, and accommodations at one or more of the NRS’s 41 reserves.

For his Mathias Graduate Student Research Grant study, UC Santa Cruz graduate student Daniel Hastings will assess water storage in Joshua trees at the NRS's Burns Piñon Ridge Reserve. The findings will help scientists conserve the species despite forecast drought due to climate change. Image credit: Lobsang Wangdu

A long track record

The $38,000 awarded this year comes from the Kenneth S. Norris Endowment Fund for the California Environment, provided to the NRS by the David and Lucile Packard Foundation. Since its inception in 1988, the Mathias Grant program has awarded a total of $906,444 to 486 students.

Most of this year’s award recipients will study aspects of ecology. These include an analysis of how forest thinning affects tree and plant communities; an investigation of how native fungal pathogens shape maritime chaparral communities; and how honeybees spread disease among other Southern California pollinators.

Gray-crowned rosy finches breed at a higher elevation than any other bird in North America, making them particularly vulnerable to the effects of climate change. Graduate student Tim Brown of UC Santa Cruz will study what makes this bird an alpine specialist. His findings will inform the conservation of mountaintop birds around the world. Image credit: Alan D. Wilson/Wikipedia

Making the most of the NRS

Multiple studies will examine the unexpected affects of a changing climate. These projects include experiments into whether ocean acidification is harming the ability of marine snails to escape predation; whether drought reduces the degree of adaptive variation in wild populations; and how climate variability affects the gray-crowned rosy finch, the highest-elevation breeding bird in North America.

Many projects are also being conducted at multiple NRS reserves. These take advantage of the natural environmental gradient the NRS forms across California, from the coast to alpine mountaintops and from rainy northern forests to southern deserts. Among these is a study of how genetics affect vulnerability and virulence among the chytrid fungus devastating amphibians in California and beyond. The study will sample frogs at nine reserves ranging from Angelo Coast Range Reserve in Mendocino to Stunt Ranch Santa Monica Mountains Reserve near Los Angeles.

Projects on other topics include a study testing mechanisms responsible for geological uplift and subsidence near Steele/Burnand Anza-Borrego Desert Research Center; an examination of the role of organic nitrogen in grassland soil stability at Sedgwick and Angelo reserves; and a biomedical investigation into the effects of high altitude on inflammation at White Mountain Research Center.

A painted lady butterfly sipping nectar from a purple phacelia at Boyd Deep Canyon Desert Research Center. UC Riverside graduate student Nicole Rafferty received a Mathias grant to study the interactions among plants and their pollinators at the reserve from the desert floor to the heights of Santa Rosa Mountains. Image credit: Lobsang Wangdu

Preparing for a career in science

The Mathias Graduate Student Research Grant program gives students experience applying for and managing research grants, and reporting on their research progress—invaluable skills for a career in science. The program also encourages students to establish studies on reserves that can become the foundation of their research careers.

Receiving a Mathias Grant signals to other scientists and institutions that a researcher's work is serious and worthy of funding. Early career support by a Mathias Grant has advanced the professional success of dozens of students over the years.

Aiding UC graduate students

The Mathias Grant competition is open to UC graduate students who submit a proposal for research to be conducted at one or more NRS reserves. Students from all disciplines are encouraged to apply. Applications are evaluated based on academic merit. Students at an early stage of their careers and in underrepresented fields of study receive preference.

All award recipients are invited to present their findings at the Mildred E. Mathias Graduate Student Research Grant Symposium. Held every three years, the symposium enables students to meet peers, interact with leading field researchers, and discuss career options. The next symposium will be held in 2022 at Bodega Marine Reserve.

Limited underground water storage make plants less susceptible to drought

Anonymous — Wed, 24 Jul 2019 22:23:44 +0000

Limited underground water storage make plants less susceptible to drought Anonymous (not verified) Wed, 07/24/2019 - 15:23 More News Robert Sanders | UC Berkeley June 24, 2019

You might expect that plants hoping to thrive in California’s boom-or-bust rain cycle would choose to set down roots in a place that can store lots of water underground to last through drought years.

But some of the most successful plant communities in the state — and probably in Mediterranean climates worldwide — that are characterized by wet winters and dry summers have taken a different approach. They’ve learned to thrive in areas with a below-ground water storage capacity barely large enough to hold the water that falls even in lean years.

Resilience from scarcity

Surprisingly, these plants do well in both low-water and rainy years precisely because the soil and weathered rock below ground store so little water relative to the rain delivered.

“The key point from our study is that, in many sites on the North Coast, the storage capacity is small relative to how much it rains,” said Jesse Hahm, a graduate student at the University of California, Berkeley. One of two first authors of the study, Hahm received support for his research from the UC Natural Reserve System's Mildred E. Mathias Graduate Student Research Grant Program, among other sources. “Because the capacity for the subsurface to store water over the wet season is small, it still rains enough, even in the dry years, to replenish the water supply. The limited below-ground storage capacity is the key mechanism that decouples the plants and how much water availability they have in the summer from big swings in winter rainfall.”

David Dralle of Sacramento State investigates water emerging from a spring. Researchers at the Eel River Critical Zone Observatory have used hillslope-scale insights into how water is stored below ground to explain state-wide patterns of plant drought response. Image credit: Jesse Hahm, UC Berkeley

Seeing a constant supply

As a result, these plants are much more resilient in drought years, as evidenced by California’s relatively unscathed North Coast during recent droughts that killed hundreds of millions of trees in the Sierra Nevada.

“Because the subsurface water gets replenished even in drought years, in the summer these plants feel the same amount of water supply below ground, no matter how much rain fell during the winter,” Hahm said. “They don’t really know if it rained a lot or a little, because they have the same amount of water stored below ground each summer.”

Abundance breeds dependence

On the flip side, plants growing today on ground that can soak up as much water as the winter rains can provide are hosting plants that will have to deal with the state’s increasingly drier climate, putting them at risk as the climate changes. This may be a problem for Sierra Nevada plant communities that are relying less on a persistent snowpack and increasingly on stored subsurface water to last through the dry summer.

Hahm and David Dralle, the other first author and a former Berkeley graduate student who is an assistant professor at Sacramento State University, describe their findings, along with their colleagues, in a paper recently accepted by the journal Geophysical Research Letters and now posted online.

Berkeley graduate student Jesse Hahm levels an automated rain gauge deployed as part of an effort to track water fluxes across the landscape in order to measure seasonal subsurface water storage. Image credit: Wendy Baxter, UC Berkeley

Rock moisture

While most people think plants rely only on water stored in the topsoil, Berkeley’s William Dietrich, professor of earth and planetary science, and recent graduate Daniella Rempe, an assistant professor at the University of Texas, Austin, recently discovered that water stored in fractured and weathered rock underneath the soil plays an equal or greater role. Their findings, based on research conducted at Angelo Coast Range Reserve, are published in the journal Water Resources Research. What Dietrich and Rempe call “rock moisture” can amount to a significant proportion of what plants rely on annually.

A major implication of the new study, Dietrich says, is that global climate models need to incorporate rock moisture into their calculations to accurately represent and predict the impacts of drought or heavy rainfall. In recent years, drought- or heat-killed trees have fueled catastrophic wildfires in California, Spain, Greece, Australia and many regions with a dry, Mediterranean climate.

“Understanding how water is stored deep within the weathered bedrock and how variations in that water supply and in rainfall affect plant water supply in that zone is extremely important in a seasonally dry climate,” Hahm said.

Statewide differences

In the new study, the researchers looked at 26 sites statewide. Locations included Angelo Coast Range Range Reserve in Mendocino and Sagehen Creek Field Station near Truckee. All were below the snow belt, so that winter rain stored below ground was the dominant source of water for the plants during the summer dry season. Using rainfall data and U.S. Geological Survey stream flow data to calculate the amount of water stored annually underground, they were able to assess the below-ground storage capacity of the soil and the weathered rock.

Of the 26 sites, only seven — all in the Northern Coast Ranges — had limited subsurface water storage capacity and fared well during the state’s recent protracted drought, between 2011 and 2016. These sites ranged from grass and oak savanna and chaparral to dense Douglas fir forests, but all were characterized by low subsurface storage relative to average annual rainfall in the area, which tends to be high. The excess water that the subsurface couldn’t store in the winter ran through the soil and fractured bedrock and ended up in the streams.

Berkeley professor Bill Dietrich surveys saturation overland flow during a winter storm. The storage of water in some landscapes is limited by the extent of weathering in the soil and fractured bedrock. Image credit: Jesse Hahm, UC Berkeley

A capacious underground sponge

The other sites, including most sites in Southern California, suffered in the drought, with vegetation die-offs and less healthy, less green plants. All were characterized by below-ground storage that is sufficient to sop up most of the rainfall that falls yearly, but that had been left depleted in drought years.

Using satellite images to gauge the productivity and health of the vegetation at each site, the researchers concluded that the sites with high relative storage capacity were the ones that varied the most between wet and dry years in how green the plants were. Sites with low below-ground storage capacity relative to average annual precipitation fared better, remaining similarly green and healthy in drought years and wet years alike.

Switching away from snowpack

Hahm noted that many plants in the Sierra Nevada rely on the snowpack to quench their thirst during typical rainless summers. But as temperatures rise with global warming, winter precipitation will increasingly occur as rain.

“In a way, this is a glimpse into the future,” Hahm said. “As the climate warms, and as the snowline elevation increases in these mountain ranges, more and more places will switch from being reliant on snowpack to being reliant on water stored in the subsurface. Understanding how this storage capacity limitation will impact plants across the state in high montane areas needs to be explored more.”

Critical zone research

The insights about rock moisture emerged from a long-term project at Angelo Coast Range Reserve, where scientists at the Eel River Critical Zone Observatory followed water from the sky through vegetation, soil and rock into the streams and back up into the atmosphere via evaporation and transpiration to chart the life cycle of water in the environment. Primary funding for the Eel River Critical Zone Observatory, which Dietrich directs, comes from the National Science Foundation (EAR 1331940).

Other co-authors of the study are graduate student Alexander Bryk and Todd Dawson, professor of integrative biology, both from Berkeley, and Sally Thompson of the University of Western Australia.