The Loess Plateau in north-central China is a large, hilly, semi-arid region roughly the size of Afghanistan. Thousands of years of farming, which intensified during the Cultural Revolution, left the former grasslands degraded and eroded. Food production was down, waterways filled with silt, and air in faraway cities suffered sand storms born on the Loess Plateau. Population that rose to 50 million people made the problems worse. Something had to be done.

Restoration began 40 years ago with significant Chinese government investments to safeguard water resources, ensure food security, and promote sustainable rural development. This was part of a US$100 billion national investment in six forest restoration programs, covering 76 million hectares of land across more than 97 percent of China's counties. In 1999, the Chinese government launched one of the world’s largest conservation programs, “Grain for Green”, in which millions of rural households worked to return agricultural lands to areas with more vegetation, tree cover, erosion-fighting terracing and payments for ecosystem services. In the Loess Plateau, funding from the World Bank and the Chinese government helped restore 4 million hectares of land, more than doubling the incomes of local farmers, reducing erosion by 100 million tons of sediment annually, reducing flood risk, and dramatically increasing grain production.

But not all of it worked. In some areas, three out of every four trees died. Competing for scarce water with people and agriculture, the trees couldn't win.

Postmortem of a large tree-planting program

Many non-native trees planted under the “Grain for Green” program were simply too thirsty. In 2011, trees in a project area consumed 550mm of water but only received 420mm of rainfall. This led to a rapid decrease in run-off, reducing the water in the rivers. In other words—the rainfall was not sufficient to sustain the trees.

Researchers found that trees had a better chance of survival on mid to low slopes, facing north, which meant that blanketing the landscape with trees regardless of the terrain was bound to fail. In higher elevations, the loose, dry loess soils weren't deep enough to hold the moisture the trees needed. Scientists concluded that native grasses should have been planted instead of trees in such areas.

Why trees?

So why were so many trees planted in this landscape in the first place? Two major reasons stand out, one technical and one cultural. Firstly, there was a misconception that trees would bring more water to the region. Secondly, there was a notion that planted trees would bring ‘beauty’ to the landscape, a perspective with roots in a non-native culture.

Cultural blinders

It is easy to blame restoration mistakes on poor science, but that underplays the importance of culture. The open, semi-arid landscape of the Loess Plateau is home to the Hui ethnic people and peppered with mosques. This landscape is very different from the cultural ideal of the Han ethnic people that make up 92 percent of China’s population and dominate its political and cultural life.

Where did the idea come from that trees would make the otherwise barren grasslands more beautiful? Did the central government impose an idea of beauty that was out of place in this semi-arid landscape? Would the Hui, whose culture has been shaped by the local climate over thousands of years, have been inclined to select a more appropriate species mix? To an outside observer, the natural landscape has its own beauty with vast hillscapes and valleys covered in bright red shrubs with green and brown grasses. The mountainsides of the Loess Plateau may be dramatic but they are not covered in trees, unlike the more moist areas of China where the Han are at home.

China has worked hard to create a sense of national unity, making Mandarin (the language of the Han people) the country’s common language, in 1912. In 1949, Chairman Mao Zedong decreed that all of China would operate on Beijing time, even though the country spans five time zones. Nature, however, will not be bound by our sense of order. What can land managers learn from the Hui people’s historical relationship with their landscape? Do ethnic diversity and biodiversity co-evolve in such a way as to improve the resilience of cultural and natural ecosystems together?

Lessons learned

The trees planted on the Loess Plateau were biological settlers, foreigners to the arid landscape. The settler trees also represent the migration of a cultural perspective. While the introduction of non-native plants attracts scientific and public attention, the cultural perspective is often overlooked. Cultural bias can be difficult to perceive, as the Chinese poem states, it is difficult to see the situation when you are deeply involved—can’t see the forest for the trees.

The restoration of the Loess Plateau is unmatched in scale, yet the allure of non-native species to engineer a desired outcome in the landscape is common globally. We need to understand the biophysical and cultural factors to build on the indigenous ecological and cultural memory of the landscape.

With changing climate and increasing populations, we need to restore landscapes to ensure the resilience of ecosystem services in the 21st century recognizing that cultural diversity is as important as biodiversity in restoration decisions.