Rush Limbaugh got a lot of grief from environmentalists when he declared that "we have more trees in the country today than when the Declaration of Independence was written." For one thing, the available data -- 850 million acres in the late 1700s, 720 million today -- did not back him up. For another, he was willfully ignoring the difference between biodiverse virgin forests and modern single-species tree farms and managed forests.
But, hard as this is for How the World Works to admit, Limbaugh was right about the general direction of American forests. For at least a century, trees have been on a growth spurt in the United States. And the U.S. is not alone: A major study published today in the Proceedings of the National Academy of Sciences concludes that in vast parts of the world, forests are expanding. In the last 15 years alone, reports the study, 22 of the most forested 50 countries in the world have experienced growth in tree stocks. Specifically, "no nation where annual per capita gross domestic product exceeded $4,600 had a negative rate of growing stock change."
In other words, there is a clear connection between poverty and deforestation. Economic growth will bring back the forests. This is a classic statement of the theory behind the Environmental Kuznets Curve, which holds that as economies mature, the environment improves. What makes this study particularly relevant is that previous attempts to determine whether there is an Environmental Kuznets Curve for deforestation have resulted in inconsistent results, so much so that some critics of the validity of the EKC have used deforestation as an example that disproves the theory.
The researchers who conducted the PNAS study added some new variables to the equation that might have resulted in their encouraging results. In addition to measuring total acreage of coverage, they also calculated density, biomass and carbon concentration. The report concludes:
Recent assessments suggest that forest transitions of the kind experienced in Europe and U.S. during recent centuries are now spreading to some other parts of the world. Deforestation does continue in about half of the 50 nations with most forest. However, 36 percent of the 50 increased forest area and 44 percent increased biomass. Without depopulation or impoverishment, increasing numbers of countries are now experiencing transitions in forest area and density. Although complacency would be misplaced, insights provided by [this data] provide grounds for optimism about the prospects for returning forests.
A couple of additional points of note: The report provides a qualified endorsement for "tree plantations" -- the kind of monocultural sources of industrial wood production that many environmentalists and NGOs criticize for their impact on biodiversity and indigenous social structures. According to the report, however, the more plantations you have, the less pressure there is on natural forests. "Thus, plantations and the trade to make them effective reduce the impact of industrial pressures on natural forests, which may be rich in soil carbon and biodiversity." The authors do not directly address how this applies to cases where natural forests are being cut down and replaced by tree farms, except to note that the two most egregious cases where this is happening, Brazil and Indonesia, are both under the $4,600 GDP demarcator. The implication being that if we want to save the rain forest in those countries, we need to figure out how to boost their economic growth and reduce poverty.
The biofuel fans at Biopact picked up the PNAS report and used it to push their own agenda, which boils down to promoting biofuel production as a way to reduce poverty in the developing world. But Biopact did not reference a key paragraph in the report, which, looking forward toward an energy-constrained future, should give pause to forest lovers.
Of course, changes in the demand for lumber, pulp, and fuel as well as food will heavily determine future land use and cover. Fortunately for forests, the consumption of timber products has lagged behind population and income. In the U.S., as early as 1987, the demand for newsprint switched from a steady and steep annual rise to a decline, which reduced the consumption from the peak of 12 million tons in 1987 to 10 million tons in 2004. Replacement of fuel wood by fossil fuel has spared forests, a sparing that increasing use of biomass fuel would reverse.
So, maybe we shouldn't be too hasty in applauding the return of the forests. They could disappear again, just as quickly.
UPDATE: Matt Cole at Globalization and the Environment says that grounds for optimism for forestry recovery are weak, in his critique of the PNAS study.