David Wolfe explores the secrets of the subterranean world and probes the profound questions posed by global warming.

 

"One doesn't have to venture far into the underground for new discoveries. Step out into the backyard, for example, push your thumb and index finger into the root zone of a patch of grass, and bring up a pinch of earth. You will likely be holding close to 1 billion individual living organisms, perhaps 10,000 distinct species of microbes, most of them not yet named, cataloged, or understood." So begins David W. Wolfe's book Tales from the Underground: A Natural History of Subterranean Life.

Wolfe wants to lead readers to a most unlikely place: to dirt, to what lives in it, and to how those of us who reside above ground can't survive without those who live below.

So he starts with the basics, with life-giving nitrogen, an essential element without which our cells could not survive or reproduce. It's abundant in the atmosphere-surprisingly, 80 percent of the air we breathe is made up of N2-yet our biochemistry isn't able to metabolize this gaseous form so our bodies can use it. Believe it or not, we all rely on a few species of invisible microbes that live in the ground to bring nitrogen into the food chain in a form that we can use.

Wolfe, a professor in the Department of Horticulture, is full of such surprises. Tales from the Underground, his engaging first book, has put him squarely on the media circuit, from being interviewed by National Public Radio, television's NOVA, and the New York Times to writing articles for popular science magazines such as Natural History.

"The whole thing was a rather risky venture," says Wolfe of the book project, which took him three years to complete, working on it in his spare time. "I was attempting to reach a much broader audience than I ever had before." For this plant ecologist, the book was a chance to indulge his unceasing curiosity about the natural world.

Chapters that touch on everything from life's rocky origins, to Darwin's experiments with earthworms, to the isolation of antibiotics from the soil allowed Wolfe to travel far afield from his day job. As an agriculture-oriented scientist with an energetic extension program, Wolfe is more typically concerned with things like farm nitrogen management. Not enough nitrogen and crops don't thrive. Yet too much results in water pollution (to levels that can be toxic to humans and aquatic animals alike) and air pollution (a nitrogen- containing greenhouse gas is released as fertilizers degrade in soil.) Over the years, Wolfe and his students have studied the Rhizobium bacteria that "fix" nitrogen, converting the N2 gas into ammonia (NH3) from which plants build the proteins that they and we need. These bacteria live symbiotically within the roots of certain plants, providing their hosts with nitrogen and receiving, in return, sugars the plants produce by photosynthesis. At mid-career, Wolfe has developed a rewarding collaboration with research colleagues (from soil scientists to molecular biologists) and farmers to focus on improving the health of New York soils.

"Many growers in New York have begun to recognize a decline in the productivity of their land compared to what their parents and grandparents saw," Wolfe says. "Something has been lost since the advent of the chemical revolution, which brought about a reliance on synthetic (nitrogen) fertilizers and pesticides." Now a biological revolution is upon us, Wolfe believes, and it is spawning discoveries of great importance to agriculture. Wolfe and colleagues are putting those discoveries to work in a new Cornell Cooperative Extension "Soil Health" program.

"We're helping farmers explore new ways to enhance and promote beneficial soil organisms while suppressing those that cause crop disease. It's a new mind-set," he explains. "We're working with nature rather than against it."

Paying attention to Mother Nature and our environment is a hallmark of Wolfe's work. Another major thrust of his research program has been plant responses to climate change-in particular, rising temperature and carbon dioxide. A recent collaboration with climatologist Mark Schwartz at the University of Wisconsin led to a startling discovery-plants may be our best indicator of global warming. Oddly enough, lilacs told the tale.

Back in the 1960s, researchers and a network of "citizen scientists" began monitoring the first bloom and leaf emergence dates of lilacs planted throughout the Northeast. Originally developed to help farmers predict spring planting dates, the data can now be used to study climate change.

"From the weather records, we know that the Northeast has warmed by about two degrees F over the past 100 years," Wolfe says.

He and Schwartz then matched up the weather data with 40-years' worth of records for the same clone of lilacs growing at 96 locations from New Jersey to Maine. They found that, across the entire region, this fragrant ornamental bloomed from one to three days earlier each decade.

"Our findings have been confirmed by studies of other plant species growing in Western Europe," Wolfe says. "These plant indicators suggest spring is coming four to twelve days earlier in many parts of the Northern Hemisphere."

The implications are dizzying. It would be one thing if the thousands of plant and animal species that now exist in a delicately timed interrelationship responded to climate change equally. But there's no reason to think they will. "Pollinators for a particular plant species must show up on dates that are well synchronized with when pollen is shedding," Wolfe explains. "What if the bees don't come until it's too late?"

Wolfe is now working with other researchers to seek out historical records of other "bioindicators" of change-bird, insect, and weed migrations into the Northeast, for example. Keeping track of invasive species from the south is a major concern with a warming climate.

"We would want to begin monitoring whether they are moving up at a faster pace than we would like," Wolfe explains. "So our farmers could be forewarned." For all of Wolfe's wide-ranging interests, it really comes down to this: "I have a great respect and affection for farmers, for what they're up against," says Wolfe of those to whom he has dedicated his life's work. "I want to help their businesses thrive while at the same time protect the environment I feel so passionately about."

For further information on Wolfe and on Tales from the Underground, go to:
www.hort.cornell.edu/department/faculty/wolfe/

 

"Many scientists now believe that life originated in the deep earth or in the sediments in the deep ocean. In both places, we find the same types of extremophiles-organisms that thrive at extreme temperatures, without oxygen or sunlight," Wolfe says.

With recent evidence of water within the deep subsurface of Mars and other planetary bodies, these extraterrestrial habitats now appear to be very similar to the habitats of the deep-earth microbes.

"So if life could have originated in deep earth, why not deep in the subsurface of Mars or on the moons of Jupiter?" Wolfe asks.

NASA's astrobiology program is now funding some of the scientists who are doing deep-earth research. "If we are going to find life beyond our planet, at least within our lifetimes, it's probably going to be microbial life that is much like the extremophiles found on Earth," Wolfe says.