The Great Reversal is Under Way in our Forests
New research shows that forests in many regions across the planet are actually becoming larger carbon sinks, thanks to an increase in density, if not in spread. Europe and North America both saw increases in carbon storage despite little to no expansion of the forest areas.
The study, conducted by conducted by Rockefeller University scientists with colleagues at Connecticut’s Agricultural Experiment Station and the University of Helsinki in Finland, and published online in the open-access journal PLoS One, gives great hope in a day and age where most environmental news seems to be another indictment on the human race.
Even nations in South America have seen carbon levels maintained thanks to increased density.
“In 2004 emissions and removals of carbon dioxide from land use, land-use change and forestry comprised about one fifth of total emissions. Tempering the fifth by slowing or reversing the loss of carbon in forests would be a worthwhile mitigation. The great role of density means that not only conservation of forest area but also managing denser, healthier forests can mitigate carbon emission,” says Aapo Rautiainen of Rockefeller University.
The researchers looked at information from 68 nations, which account for 72 percent of the world’s forested land and 68 percent of reported carbon mass. Starting with the United States, thanks to the continuing inventory of forest area, timberland area and growing stock since 1953 maintained by the U.S. Forest Service, the researchers were able to determine that while U.S. timberland only grew by 1 percent between 1953 and 2007, the combined national volume of growing stock increased by an impressive 51 percent, increasing a healthy increase in density.
Moving out from the U.S., the team looked at the 2010 Global Forest Resources Assessment compiled by the UN Food and Agriculture Organization (FAO), which provides consistent figures for the years 1990 to 2010, and were pleased to see a similar pattern in other continents.
Countries in Africa and South America lost about 10 percent of their forest area over the two decades studied by the FAO, but lost somewhat less carbon, which indicates a small rise in forest density. Asian forest density rose during the second decade of the study period in 10 of the region’s countries, but was offset by the massive loss of density and sequestered carbon in Indonesia. And Europe had acted very similarly to the U.S., adding carbon well in excess of the estimated carbon absorbed by the forested area.
Co-author Paul E. Waggoner, a forestry expert with Connecticut’s Agricultural Experiment Station, says remote sensing by satellites of the world’s forest area brings access to remote places and a uniform method. “However, to speak of carbon, we must look beyond measurements of area and apply forestry methods traditionally used to measure timber volumes.”
“Forests are like cities: they can grow both by spreading and by becoming denser,” says co-author Iddo Wernick of The Rockefeller University’s Program for the Human Environment.
“With so much bad news available on World Environment Day, we are pleased to report that, of 68 nations studied, forest area is expanding in 45 and density is also increasing in 45,” says study co-author Pekka Kauppi, of the University of Helsinki, Finland. “Changing area and density combined had a positive impact on the carbon stock in 51 countries.”