New study confirms continuing forest loss in most countries
New study confirms continuing forest loss in most countries
mongabay.com
November 13, 2006
Forest cover continues to shrink in most countries around the world, though forest expansion in some countries gives hope that net deforestation may be peaking, according to a study published this week in Proceedings of the National Academy of Sciences.
Researchers base their optimistic outlook on a new formula, dubbed “Forest Identity”, that measures forest cover based on the volume of timber, biomass and captured carbon within an area, rather than the extent of tree cover. Using data from the Food and Agriculture Organization of the United Nations (FAO), the international team of researchers from the Rockefeller University, the University of Helsinki, and other institutions, found that “growing stock” — trees large enough to be considered timber — expanded over during the 1990-2005 in 22 of the world’s 50 countries with most forest cover. The study confirmed earlier research that found forest cover is generally expanding in the world’s richest countries, while declining in the world’s poorest and most biodiverse countries. However, the growth of forests — especially plantations — in northern countries and scattered developing countries like China, India, and Vietnam does not offset the net loss of biodiversity and carbon sinks from deforestation in the tropics, especially Brazil and Indonesia.
Deforestation in Madagascar. While Brazil lost an average of 3.1 million hectares of forest per year between 2000 and 2005, primary forest loss was 3.5 million hectares per year. Plantations and growth of secondary forests help offset primary forest loss.
Includes plantations, non-natural and degraded forests |
Nevertheless, the researchers say that Earth’s two most populous nations — China and India — have reached an equilibrium point in where they do not produce a net increase in carbon dioxide emissions from change in forest cover. Though its old-growth forests continue to be cleared at the seventh highest rate in the world, net forest growth in the United States actually helps mitigate its greenhouse gas emissions. For other counties, including Denmark, France, Switzerland, Portugal, and Scotland, change in forest cover transitioned from negative to positive in the 19th and early 20th centuries. The researchers say the transition is tied to wealth: as a country become richer, it becomes greener. The paper pegs per capita gross domestic product of US$4,600 (roughly equivalent to that of Chile) as the tipping point between deforestation and reforestation.
At the other end of the spectrum, deforestation in Brazil and Indonesia continues to be a significant source of carbon dioxide emissions. Globally, deforestation is responsible for around 20 percent of greenhouse gas emissions according to the U.N. Some research suggests that as atmospheric carbon dioxide levels rise, trees could absorb greater amounts of carbon into their tissues, producing thicker forests.
Using their new formula, the researchers found that growing stock fell fastest in Indonesia, Nigeria and the Philippines, and increased fastest in the Ukraine and Spain. In terms of total cubic meters of growing stock, Indonesia and Brazil were the big losers, while the U.S. and China were the big gainers. The researchers noted that biomass and carbon expanded in “about half” the world’s most forested countries.
The researchers say that the global “transition to a greater sum of forests” is dependent on Brazil and Indonesia, where 2.8 million hectares and 1.9 million hectares of forests were lost annually between 1990 and 2005.
“The main obstacles to forest transition are fast-growing poor populations who burn wood to cook, sell it for quick cash and clear forest for crops,” said study co-author Pekka E. Kauppi, of the University of Helsinki. “Harvesting biomass for fuel also forestalls the restoration of land to nature.”
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This article used information from past mongabay.com articles and a news release from Rockefeller University.
