Indiana University Research & Creative Activity


Volume 31 Number 1
Fall 2008

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Tom Evans
Tom Evans
Photo © Tyagan Miller

Indiana forests
Photo by Shanon Donnelly; courtesy Tom Evans

The Shape of Forests

by Ken Kingery

It was a typical morning in Korat, the northeast region of Thailand just 30 miles from the Cambodian border, during the dry season. Temperatures regularly reached the low 90s under an oppressive mid-afternoon sun, but the morning was a cool 70 degrees, and the constant crowing of roosters forced Tom Evans from his thin mattress on the floor of the village leader's hut. Although the accommodations were spartan, Evans rose from a restful night of sleep. The two inches of mattress made the house's floor of teak--an amazingly hard native wood--somewhat more bearable. Evans stepped down from the raised house in long sleeves and pants, to protect himself from the mosquitoes, and flipped open his laptop to work with data collected the day before.

But he wasn't alone.

After a couple of minutes, Evans mindlessly brushed some ants from his hands. Minutes later, he brushed even more from the keyboard. Puzzled, he lifted his laptop to search for the source of parading insects but found nothing.

Thinking it strange, he shrugged it off as a consequence of working in the field.

Ten minutes later, when the ants kept appearing over and over, Evans realized the colony had tried to make his laptop their new home.

"I would guess a couple of hundred drones followed the trail of the first departee," says Evans, currently an associate professor in the Department of Geography at Indiana University Bloomington. "I quickly turned my laptop off because I didn't want to damage it by frying the ants inside. I really wanted to get some work done, but instead I spent hours just sitting and waiting."

The Hoosier Connection

Evans's ant story provides a loose connection to the idea behind much of his research, especially his current research projects at IU's Center for the Study of Institutions, Population, and Environmental Change (CIPEC).

The idea is that large-scale changes are the result of many individual interactions. In the case of the colonized laptop, the individuals are the ants, and their interactions are the ways they followed each other's trails. The observable result is the colony moving out of the laptop.

But Evans doesn't study ants at CIPEC, he studies people and how their individual decisions influence the way an entire community shapes its living environment. In Evans's work, the individuals are households that communicate and observe each other's actions, making decisions together on how to best use their land's resources. These decisions have many effects, but Evans is particularly interested in how they affect forests, in south-central Indiana and around the world. Because forests provide important habitats, carbon sinks critical for global cycling, protection for water resources, and products for many communities worldwide, the trajectories of forest-cover change are an important component of global sustainability.

With support from the National Science Foundation, Evans co-directs CIPEC, a center that uses novel techniques to answer questions concerning sustainability. He takes a three-pronged approach in his research: experimental, observational, and spatial. The observational side is the most straightforward. Using aerial photographs taken over the past 80 years in Indiana's south-central region, Evans and his colleagues get an overview of how the land has changed. Satellite images are readily available back to 1972 when satellites first began mapping the earth. To go back as early as the 1930s, however, Evans and his colleagues have had to collect many historical black-and-white aerial photographs.

Scientists know that Indiana was more than 90 percent forest in 1800, but dropped to less than 10 percent by 1900--second only to Ohio for the greatest drop in forest cover. Since that time, forests have made a comeback. Current estimates put forest coverage at 20 percent in Indiana. With the old photographs, Evans and other scientists can determine when this rebound began, how fast it happened, and what is happening today.

"Being able to go back in time has allowed us to see that much of the reforestation in south-central Indiana really happened in the early 20th century," Evans says. "But the rate of reforestation has slowed down. The question is why it has slowed, and what does the future hold?"

Will the rate of reforestation continue to decline until it reaches a threshold? If so, once at that threshold, will forestation remain constant, or begin to decline again? What drives these trends, and can they be predicted? To answer these questions, researchers at CIPEC are turning to the south-central Hoosiers themselves.

Greenbacks and Greenery

The second prong of Evans's research involves simple but numerous surveys. These household surveys and interviews attempt to discern why one family makes the decision to let a parcel of land remain in forest while someone next door, with basically the same plot of land, makes an entirely different decision.

Some economic theories characterize landowners as financially driven decision makers focused on determining how the most money can be made--use the land for pasture, for growing crops, for harvesting timber, or leave it be and take a job in the city. In the latter case--leaving the land to the trees--may lead to growth in forest cover over time.

The CIPEC project seeks to understand how differences in decisions lead to complex patterns on a regional scale. In the case of south-central Indiana, a land parcel might be entirely forest with the exception of a house and road access, or a complex mosaic of patches of wetland forest, lowland pasture, and forests on steep slopes. Each small piece has its own pattern or signature, which, when taken as a whole, compose the regional-scale pattern of forest cover. 

"There are emerging forces that drive these choices--the development of urban growth or the impact of biofuels," Evans explains. "The price of corn is so much higher now that areas which went out of production in the past are going back into production. Areas that might have converted from agriculture to forest might now just stay in agriculture. We look at long-term trajectories to examine the implications for future patterns, but what's really valuable is combining physical science and social science--how forests grow, how people make decisions, and how they work together."

The Spatial Frontier

The final prong to Evans's research--and possibly the most novel--involves spatial experiments with high-tech satellite surveillance systems and geographic information systems (GIS). "At CIPEC, we use spatial experiments in coordination with other traditional methods of studying forest-cover change," says Evans.

GIS is a way of representing geographic space. Data from sources such as aerial photos are overlaid with geographic data on slopes, soils, and even land ownership boundaries. Armed with this information, scientists can investigate trends in geographic or political differences that lead to deforestation and other phenomena.

"CIPEC is doing some pretty exciting research," says Elinor Ostrom, a professor of political science at IU Bloomington and an international expert on the governance and management of natural resources. "It is making use of very powerful technology to understand the factors of forest re-growth."

Some of these technologies are housed in an unusual research facility called the Interdisciplinary Experimental Laboratory, located in IUB's Woodburn Hall. Formed with funding from the National Science Foundation and IU, the laboratory brings together experts from psychology, cognitive science, economics, political science, and conservation biology, who work together to study how social and environmental factors influence human behavior.

"It's stimulating to get in groups, discuss viewpoints, and compromise on what each of us thinks is the best research plan," Evans says. "We bridge and integrate different approaches and theories about how landscapes change the way they do."

One of Evans's spatial experiments involves Hoosier residents in a computer simulation. Participants are presented with a virtual landscape and asked to make decisions about it throughout an accelerated timeline with constantly changing situations. The simulation typically involves two resources such as crops and livestock. As prices and the landscape change during the experiment, CIPEC researchers examine what decisions people make about their land, and why.

"If we see the same variability of decision making in the simulation as we see in our observations, it gives basis to support ideas of variability in the real world," Evans says. "Some people might make decisions motivated by financial factors, some because of environmental preservation, and others based on historical traditions. But no one makes perfectly informed decisions, and trying to integrate that feature into our theories is extremely important."

Going Global

Of course, variability in human decision making is a universal phenomenon. With colleagues from IU and Princeton University, Evans is tracking reforestation taking shape in Sao Palo, Brazil. Forest transition theories state that as economic opportunities in cities increase--as they currently are in Brazil--rural land use drops. Another theory is that some areas are not suitable for long-term, sustained agricultural production. These are the first plots to turn back to forest when people realize the land is not yielding as well as in the past.

On the opposite side of the forestation coin are Laos, China, and Thailand. Regions in these countries that used to follow a rotating crop schedule, keeping the land sustainable for centuries, are now transitioning to rubber plantations.

Evans is working with colleagues at the East-West Center in Hawaii to look at the hydrological, environmental, social, and economic implications of shifting cultivation to rubber. Rubber plantations are considered forest by some definitions of the term, but these areas do not provide the same benefits as traditional types of forests. Economic benefits are offset by potentially negative ecological impacts. The transition from traditional forests to rubber plantations has had an impact on soil erosion, water levels, and water flows in Southeast Asia.

There are also important moral questions about who deserves to use the land in the way they wish in order to develop their economies as quickly as possible. So far, those who switch to rubber cultivation early make out better than those who are late to the table. Rubber fetches a higher return than traditional crops so when some households take the risk of converting land to rubber, economic inequalities ensue. More and more households are starting to convert land from agricultural crops to rubber cultivation, which may even out these inequalities over time, but Evans notes that the long-term economic impacts of this transition are unclear, given the uncertainty of future trends in rubber prices.

The rate of forest destruction happening now in regions of Laos, China, and Thailand is analogous to what happened in the United States during the 1800s. What is different today is a greater awareness of the global impact of deforestation, an awareness that raises complex ethical questions about land use. Efforts to slow down the rate of deforestation have clear global environmental benefits, but also affect the ability of rural people in less developed countries to make a living. "The key to managing global environmental change," Evans says, "is how to make the best environmental decisions for our global population that take into account the livelihoods of local populations." Exploring these issues has been exciting for Evans and for others watching his work.

"As a leader in dynamic system modeling and land use change, Tom's work is consistently cutting-edge, scientifically important, and vital to the development of land change science," says Steve Walsh, a professor of geography at the University of North Carolina, who was Evans's Ph.D. advisor. "His work has demonstrated the intrinsic link between people and the land."

As much as Evans enjoys his research in the laboratory using satellites and computer simulations, he misses work in the field and the luxury of immersing himself in a culture for months at a time without the pressures of teaching a class, running a research center, or directing students.

One of his best memories and most poignant lessons came during fieldwork in Thailand.

In one of Thailand's poorest regions, Evans would hop on a moped with a backpack and ride to a village, show up unannounced, and ask the villagers who owned which parcels of land. There were usually about 50 or 60 people per village. With his Thai research collaborator, Evans would find the village leader, explain why they were there, and ask for someone to guide them and provide food and lodging in the village. The villagers, often living in desperate circumstances, would feed and chat with Evans and his companion, even after 10 hours of guiding them in the hot Thai sun.

"Imagine if this happened in the United States," Evans says. "A foreigner shows up, wants a place to stay--there's no hotel for miles--and someone to walk with for a few days. That wouldn't work, but in this area of Thailand, in each of the 20 villages, it did. And in 18 of the villages, the headman would invite us to his house and provide a village representative the next day. It was an amazing experience to show up unannounced and have people be so gracious and generous."

In one village, the headman asked how Evans's research would benefit his village. "I told him what I was doing right then probably would not benefit the village directly, but I hoped the science being done would have a broader impact down the road," Evans recalls. "Then I asked what they needed or wanted. They said they wished there was a factory nearby for employment opportunities beyond working in the field. It was very sobering, because what I was doing had no potential for that kind of an immediate, direct impact."

Years later, Evans believes his work is contributing to knowledge that will improve people's lives and our understanding of the mutual reliance between people and the environment. And he still loves working in the field. During his sabbatical in 2009, Evans plans to continue his work in Brazil and Japan.

Ken Kingery is a science writer for the University of Idaho.