UC ANR research to determine future climate change impacts today

Scientific evidence of a warming climate in California and across the globe is clear, but the impacts on ecosystems and agriculture are still difficult to predict.

Sophisticated computer models are used to forecast future climate. Understanding that temperature and precipitation levels will change in the future does not tell the full story: UC Agriculture and Natural Resources researchers also want real-world experience under those future conditions.

Moreover, some agricultural operations have higher sensitivity to the changes than others. Rangeland forage is particularly sensitive to climate changes since, unlike irrigated agriculture, ranchers rely solely on precipitation. They have no control over how much and when it rains.

“It's tricky business,” said rangeland expert Jeremy James, the director of the UC Sierra Foothill Research and Extension Center in Browns Valley. “It's not easy to forecast. We have to address the uncertainty in a realistic manner.”

Discovering climate change impact on rangeland

In order to study different climate projections on rangeland, James and Maggi Kelly, director of the UC ANR Informatics and Global Information Systems special program, have begun development of a research site that will allow scientists to manipulate the temperature and rainfall on sections of rangeland to understand what would happen under predicted weather scenarios.

With a $220,000 National Science Foundation grant, construction is now underway on a four-acre site at the research center that will help scientists learn how temperature and precipitation will impact growth and diversity of forage that ranchers use to raise their livestock.

“We need to know how rangelands will respond when conditions change,” James said. “Will we grow more, but dry out earlier? Will we have more medusahead (an undesirable rangeland weed) or more soft chess (a high quality forage)?”

When complete, 16 shelters on steel tracks will be connected to computer systems and hydraulic motors to move them up or down a research plot. The shelters and other equipment will allow scientists to precisely control the amount of precipitation (or irrigation water) that rains onto the plot. Other systems will give researchers control of air temperature.

“This facility isn't designed for one type of research,” James said. “It is designed to conduct a wide variety of research by scientists over the next several decades. With this setup, we can look at the effect of climate change on soil biological communities, soil carbon, insect communities, plant-insect interactions and oak seedling recruitment.”

The research results from the project should provide ranchers and land managers a better understanding of how climate change may impact agriculture and ecosystem function on rangeland while also providing important information on how to minimize impacts of these changes.

Some aspects of the research facility's development are not covered with funding from the National Science Foundation. The scientists are looking for additional support to complete the project.

For more information, contact James at jjjames@ucanr.edu. 

Current work underway at the Sierra Foothill Research and Extension Center

The Sierra Foothill REC, a 5,000-acre facility on the Yuba River, has supported research, education and outreach in the Sierra foothills since 1960. Multiple lines of research are being conducted at SFREC. During a recent workshop, scientists from UC Davis, UC Berkeley and UC Cooperative Extension shared a sampling of their work at SFREC.

UCCE livestock and natural resources advisor Dan Macon described a project aimed at helping ranchers make decisions about maintaining a cattle herd when faced with impending drought. Ranchers are reluctant to sell off their cattle even when the near future weather forecast is dire.

“Science tells us you shouldn't feed your way out of a drought,” Macon said. “But you want everything to stay the same. You want to maintain your genetic potential and keep cows that are familiar with the area.”

Working with ranchers, the research project will compare management practices to determine the best way forward when the future looks meteorologically bleak.

“We're assigning cows to a traditional weaning and early weaning groups,” Macon said. “They'll be out on the range from March to early September under different parameters. We're also tying in economics, the value of genetic potential and the value of having cows who know the landscape.”

Research by University of Oregon post doctorate researcher Ashley Shaw is looking into whether compost applied to rangeland will help mitigate climate change by sequestering more carbon, and also benefit forage under drought by increasing the soil's water-holding capacity and improving nutrient delivery.

Preliminary results are promising. A single application of 1/4-inch of compost resulted in forage production that was higher than areas where no amendment was applied and areas that were treated with a chemical fertilizer.

“The biggest impact was under drought shelters,” said Shaw, referring to PVC frames that were covered with plastic during rain events to understand the impact of the treatment under dry conditions. “In the drought plots, the areas where compost was applied are staying green longer.”

A defining research tool at SFREC is a dataset that includes information on monthly rainfall and forage production going back 40 years.

A review of the data shows surprising variations and correlations at the center, where forage production averages 3,000 pounds per acre, but ranges from about 1,000 pounds per acre in 1987, to over 5,000 pounds per acre in 2018, when there was so much growth, “we didn't have enough animals to graze,” James said.

The dataset paints a spectrum of the variation that ranchers across the state must navigate to manage their livestock and rangeland in a way that is profitable and ecologically sound. Research at the Sierra Foothill REC offers invaluable information to help them better understand the ecosystem and make informed decisions.

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