Dennis Baldocchi

Leader in bio-atmospheric studies at Berkeley credits UNL education – Meet Dennis Baldocchi

UNL experts now with SNR fostered Baldocchi’s career

On his web page at the University of California at Berkeley’s site, the first line of climatologist Dennis Baldocchi’s profile reads: “The biosphere and the atmosphere are coupled to one another.” But this is a deceptively simple statement. “I tell people we are measuring the breathing of the biosphere,” he said.

Baldocchi is chair of the ecosystem sciences division and professor of biometeorology at Berkeley. Most of his career, he has worked on the complex interactions among photosynthesis, respiration, transpiration, their effects on the atmosphere and, in turn, the atmosphere’s modification of vegetation.

He is among the leaders doing this work and learned many of his most fundamental lessons at UNL. These have had to with carbon cycles, and increases in atmospheric CO2 in particular, and have only increased in importance as the facts of global warming – and carbon dioxide’s role as a contributor – have become increasingly clear. He and colleagues can even put fairly accurate numbers on much of it. They can then put those numbers into sophisticated computers that can begin to model the atmospheric processes that feed the part of the planet that feeds everything else, its primary production: plant life.

Growing up on a walnut farm in California, Baldocchi received his bachelor’s in atmospheric sciences at the University of California at Davis. He then came to the University of Nebraska–Lincoln and completed his master’s and doctorate under SNR Professor Shashi Verma in the late 1970s and early 1980s. Much of his present work is rooted in those experiences, he noted.

There was a collection of experts at UNL’s Center for Agricultural Meteorology and Climatology (CAMAC), working in climate, drought, carbon cycling and storage in plants and soil and bio-atmospheric interactions in general. Even then, there was an emerging sense that the increase of certain gases was probably leading to a warmer Earth. CAMAC became the Department of Agricultural Meteorology and then part of the UNL School of Natural Resource Sciences, now the School of Natural Resources (SNR).

"Norm Rosenberg was there. So was John Norman, Shashi Verma, Blaine Blad and others. They were leaders in climate change and carbon dioxide exchange and were looking closely at plant canopies and their interaction with the atmosphere,” he explained.

Rosenberg is a nationally and internationally known scientist who went on to work for Resources for the Future in Washington, D.C., an environmental think tank. Blad was the first director of the School of Natural Resource Sciences.

Verma is the SNR micrometeorologist who heads up the Great Plains Center for the National Institute for Global Environmental Change (NIGEC). He has done pioneering work on what are called “trace” gases and their movements, especially their exchange across plant-air boundaries and their sequestration, or storage, in soil and in plant tissue. Don Wilhite and the UNL National Drought Mitigation Center also were becoming established as leaders in climate change and drought readiness.

"Some of the questions I’m working on now came from my experiences in grad school,” Baldocchi said. “There I was working on agricultural ecosystems, and now I’m working on oak savannas and other ecosystems,” he added. “The most significant thing that’s changed since then has been our ability to take measurements 24/7 (continually), year in and year out.”

Verma, he noted, was a key in that he developed the “eddy covariance” technique of measuring gas exchange.

"This is a method of direct measurement of carbon dioxide exchange through up- and down-drafts of air. We can track the enhancements or deficits of carbon dioxide in the air and see the net CO2 flux (variations),” he explained.

Baldocchi puts it this way: “The central focus of my research is on the physical, biological, and chemical processes that control trace gas and energy exchange between vegetation and the atmosphere. Carbon dioxide, water vapor, ozone, sulfur dioxide, isoprene, monoterpenes, methane, NOx and nitrous oxide are among the trace gases that interest me.”

He explains that different stands of plants, keys to defining an ecosystem, react differently to variations in the atmosphere and have to be monitored and modeled in detail. Key variables include albedo, or surface reflectance, aerodynamic roughness, leaf area, canopy height and surface resistance to trace gas exchange.

Baldocchi also said that, with colleagues around the world, he’s working with many ecosystems, including temperate and boreal forests, crops, orchards, chaparral, grasslands, savanna woodlands and wetlands. It’s an attempt to bring a huge amount of data and theory together. He and others are coordinating with an international group called FLUXNET. It combines data from various regional networks to better model how climate, soil and plant variables affect trace gas fluxes in and among many ecosystems.

Baldocchi sees his time at Nebraska as crucial to his professional development. He also noted that, as with many major universities, UC-Berkeley has a College of Natural Resources. The major change since his time with CAMAC has been that such schools, once devoted mostly to agriculture, are now learning about and lending their lessons to the study of other ecosystems.

"Ag taught us a lot. Now it can go the other way around too,” he noted.

-- by Charles A. Flowerday, editor, SNR