World's Forests Will Continue To Shrink
October 11, 2013

Mathematical Model Predicts That Forests Will Continue To Shrink

Brett Smith for - Your Universe Online

As developing nations continue to expand their land use, the area around the world covered by forests will decline and then stabilize at a lower level, according to a study published on Wednesday in the journal PLoS ONE.

In the study, researchers looked at trends around the world to create a mathematical model for future land use. The study team’s most-likely model predicts that forests will drop from covering 30 percent of Earth's land mass to 22 percent within the next two hundred years.

To reach their conclusion, scientists from Princeton University and the University of Guelph in Canada used several hundred years of worldwide land use data from the United Nations Food and Agriculture Organization and many other sources. This data was formulated into the team’s mathematical model for land use transitions, along with deforestation and reforestation trends. The models were driven by three key factors: agricultural yield, per capita food consumption, and world population change over time.

The team noted that forest cover loss has stabilized and even grown slightly in industrialized nations. In the developing parts of the world, forests are shrinking as populations grow and claim more land for housing or agriculture. Since 1990, forests have shrunk by more than 70 million hectares worldwide, a land mass bigger than the entire country of France.

"This model is helpful in that we can look back at where we've come from, but its real usefulness is in predicting where we're most likely heading," said study author Madhur Anand, an ecologist at the University of Guelph.

"With growing international trade in forest products playing a role, it is more informative to look globally at forest cover than it is to do a nation-by-nation analysis,” she added.

While the study model quantifies how much farming technologies reduce the amount of land needed for food production, humans will eventually use about two-thirds of the world's land area, if world population reaches 10 billion as predicted. With 15 percent of Earth's land considered unfit for agriculture, only 22 percent of the world’s land area would be left for forest and wild pasture conservation.

"We tried to keep this model simple so there aren't too many unknown parameters," said Anand. “We realize that no one can determine the future, and there could be drastic changes in agricultural yield, food technologies or diet which could impact on our findings, but we attempted to explore those kinds of changes in our scenarios.”

"Based on this model, we are most likely going to see forest cover decline around the world,” she added. “Countries need to realize that this is a global issue, and if forests are to be preserved, and even grow, co-operation through intergovernmental organizations will have to continue to happen. Industrial countries could, for example, disseminate technologies to developing countries, reducing the amount of land needed for agriculture. Otherwise, we will see forests get smaller and smaller."

The study authors said if food production, land use and consumption stabilize, reforestation could grow forests to about 35 percent of the globe, but only if these stabilizations occur within the next 70 years.