China Plants a Record Number of Trees—but Only One Kind

What if you undertook the world’s largest reforestation program but planted the wrong trees? In a sense, that’s what China has been up to for most of this century. Since 1999, it has spent $47 billion planting trees on 69.2 million acres of abandoned farm fields and barren scrubland.

That’s an area almost equivalent to New York and Pennsylvania combined—and should be great news in an era of worldwide deforestation. Moreover, from China’s point of view, the program has succeeded at its original purpose, controlling soil erosion. But the vast majority of the new forests consist of only a single tree species, according to a new study in the journal Nature Communications. That is, China has been creating tree plantations—monocultures, not forests—and with nonnative trees. That choice has sacrificed one of the major benefits of healthy forests: diversity of plants and wildlife.

The study, led by Princeton University researchers, puts an optimistic spin on these findings. The coauthors argue that China could easily switch to mixed forests instead of monocultures and eventually to native forests. This change of focus “is unlikely to entail major opportunity costs or pose unforeseen economic risks to households.”

The change would also be timely because the earliest plantings under China’s Grain for Green Program were aimed at fast growth and income production for local farmers. That means some plantations are approaching the time for harvest and replanting. Taking that opportunity to make the relatively minor shift to mixed forests, with two to five tree species, would provide all the same economic benefits, the researchers argue, while significantly increasing populations of birds, bees, and other wildlife.

China began the Grain for Green Program largely because of major erosion and flooding problems resulting from the massive deforestation under Mao’s disastrous Great Leap Forward of the late 1950s. The reforestation program primarily operates with cash payments to encourage rural households to plant trees on sloping fields and scrubland. Timber production has been the main economic focus, with farmers typically planting only one kind of tree, typically either eucalyptus, Japanese cedar, or nonnative bamboo species.

Because there is no nationwide system for tracking tree composition from province to province, study lead author Fangyuan Hua and her coauthors first had to sift through 258 scholarly publications to determine what had been planted and where. Of 202 locations reported, 166 were monocultures.

Then, to figure out how different forest types affected wildlife, the researchers undertook field studies of reforestation sites in south-central Sichuan province, counting birds and bees as a stand-in for overall diversity. They found that Grain for Green Program forests, overall, had 17 to 61 percent fewer birds than native forests, and 49 to 91 percent fewer bee species. In some cases, monoculture forests were worse than cropland for wildlife.

The level of loss was far lower for mixed forests than for monocultures. In interviews with farmers, Hua learned that, “in quite a few cases,” they had already made the switch to mixed forests after learning the hard way that monocultures were more vulnerable to pests, diseases, and marketplace fluctuations. The researchers found no significant loss from the shift to mixed forests, even when they looked only at the economic benefit from timber and ignored other potential benefits.

In an interview, Hua noted that in April of this year, China’s central government promulgated a new system for recognizing and paying for ecosystem benefits, possibly making it more amenable to including biodiversity among the considerations for the reforestation program. Moreover, China’s system of government, with a clear line of command from the Central Committee down to the grassroots level, has the potential to make that sort of major change far more rapidly than a democratic system could.

Coauthor David Wilcove, a Princeton University ecologist and an evolutionary biologist, added that a new focus on biodiversity could make the Chinese program a model at a time when many other nations are just beginning to formulate reforestation plans.

Everywhere in the world, he said, “people are leaving the rural areas, moving into urban areas.” Even in Sichuan, “I remember being struck by the number of people working in the fields who were quite elderly. There weren’t any young people.” For urbanization to work, the best agricultural land has to become far more productive. But in marginally productive areas, “I think we are going to see bona fide land abandonment, and that’s going to create opportunities around the world for reforestation.”

“The critical policy question is how to restore forests that provide multiple benefits to society, including preventing soil erosion, providing timber, and sustaining wildlife,” Wilcove added. As the first country to undertake large-scale reforestation, China has the opportunity to lead the world by doing reforestation right.