A fine line: new program predicts when human impact becomes too much

/ Morgan Erickson-Davis, staff_writer

Scientists at Stanford University recently unveiled a new modeling program that can predict the response of the environment to the land-use changes of human communities. Using their model, they found that natural resources can support humanity – up to a certain point.

Modeling program could be used to better manage areas held by indigenous communities

Indigenous groups control approximately half of the world’s vegetated areas. As globalization changes the ways in which traditional communities interact with the land on which they live, it is important to be able to predict how the surrounding environment will respond.

Scientists at Stanford University recently unveiled a new modeling program that can predict the response of the environment to the land-use changes of human communities. Using their model, they found that natural resources can support humanity – up to a certain point. They recently published their findings in the journal Environmental Modelling & Software.

Orang Asli children, an indigenous group of peninsular Malaysia. Increasingly, communities are being displaced from their native lands to make room for plantation development. Photo by Sheema Abdul Aziz.

Their model showed that in an area in which food is acquired through mostly hunting and with some cultivating, a human community can remain in-balance with the surrounding environment if it stays within a certain population range.

“Once indigenous populations move outside that [range], the land use rapidly shifts to another state characterized by a much lower forest cover, with negative impacts on both biodiversity and carbon stocks in the vegetation,” said Eric Lambin, a professor and senior fellow at the Stanford Woods Institute for the Environment.

Lambin worked with project lead Jose Fragoso, a senior scientist at Stanford, and others to develop the model by incorporating many different ecological factors that are known to affect native communities, such as vegetation diversity and deforestation rate. They then projected how changes in these factors would impact the growth rate of communities through food availability. While the actual dynamic between human communities and the environment is more multifaceted and also involves a complex of social factors like education and policy, the researchers believe this initial version of their model will still be useful in predicting land changes.

“This makes it more of a universal model, because all people need calories,” said Fragoso. “They must meet their daily caloric requirement. If they farm more to do that, then they hunt less, or vice versa. But that drives the system and causes all the changes to occur.”

According to World Resources Institute, just 20 percent of the world’s old-growth forests still existed as of 2009, an amount that is getting smaller by the day as land is cleared for human development. Much of that which remains is home to communities that have lived in concert with forests for millennia. But many of these communities are being pressured by logging companies and other outside interests to change the way they interact with their surrounding environment.

The researchers suggest their model could be used by governments and institutions to help manage undeveloped lands held by indigenous communities.

“Few such areas may still remain in the modern world, but preserving that cultural diversity is very important,” Lambin said. “The model helps us to understand under what conditions these traditional, indigenous systems can be sustained.”

Deforestation for palm oil plantations in Sabah, Malaysia. Indigenous communities are often pressured by companies to give up their land for development. Photo by Rhett A. Butler.

Note: the original version of this article implied that Lambin led the team that developed the model. Jose Fragoso was actually the project lead. We regret the error.


  • Iwamura, T., Lambin, E. F., Silvius, K. M., Luzar, J. B., & Fragoso, J. (2014). Agent-based modeling of hunting and subsistence agriculture on indigenous lands: Understanding interactions between social and ecological systems. Environmental Modelling & Software.

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