Since the 1990s, Vietnam has managed a seemingly impressive forestry trick: Although overall forest cover in the country has increased, so have its exports of wood goods, like patio furniture. So how did the Southeast Asian country manage the feat?

The answer to the riddle: forests felled elsewhere, often illegally. The lumber first came in from neighbors Laos and Cambodia and now is coming from Malaysia, Myanmar and Indonesia, among others, according to a new analysis in today's Proceedings of the National Academy of Sciences by geographers Patrick Meyfroidt and Eric Lambin of Belgium's Universite Catholique de Louvain.

All told, forest now covers roughly 38 percent of Vietnam, up from around 25 percent since 1987, according to figures the authors compiled from the Food and Agriculture Organization of the U.N. That increase is thanks to government policies that restricted logging and "shifted the source of wood from natural forests toward plantations and imports," the researchers wrote. But, they added, the domestic forest industry also shut down "because of a growing scarcity of raw materials."

In other words, Vietnam had already logged almost all its high-value trees and much of this new "forest" is actually tree plantations. Vast fields planted with rows of a single type of tree account for half the increase. Plus, actual "regrowths have a low density and poor biodiversity," the researchers wrote. "The degradation of primary forests continues."

In fact, in 2005, the country produced around six million cubic meters of processed wood products—from plywood to deck chairs—and exported nearly six million cubic meters. While domestic lumber supplies and legal imports are responsible for some of that, nearly half—48.1 percent—must have been supplied illegally in order to account for the sheer bulk of exports. That cancels out nearly 40 percent of the Vietnamese regrowth (which means more than 60 percent of the forest represents new growth—and a significant carbon sink).

But who is to blame for this continuing degradation of Southeast Asia's forests? After all, Vietnam is merely exporting cheap wood goods snapped up by American, Chinese and European consumers. The researchers argue that the responsibility should be "shared between the country consuming Vietnamese products, Vietnam that imports illegal timber, and the source countries where illegal harvesters often collude with officials."

Image: © / Thomas Bradford