Afforestation and management

In addition to the Mongolian Scots pine, nearly 500 plant species that can be used as windbreaks and for sand fixation have been identified in China's decadeslong sand control practice. The recently published book Common Plants Used in the Three-North Program includes 178 tree species, 177 shrub species and 143 herbaceous plant species.

"After confirming the plant species, the second key to our sand control efforts has been scientific afforestation," said Dang.

Through continuous exploration, sand control pioneers have formulated scientific afforestation plans based on the different natural conditions in various regions.

"Usually, we need to use straw grids for sand fixation, while also introducing shrub species such as Salix gordejevii and Artemisia halodendron to follow up. Only under such protection can the saplings of trees like Mongolian Scots pines survive better," Dang said.

Wang Feng, director of policy and strategic development for combating desertification at the Chinese Academy of Forestry, explained that a straw grid involves inserting discarded wheat straw into the sand, burying half the straw while leaving half above the surface, forming a checkerboard pattern. This method can prevent windblown sand on the surface and help retain water to a certain extent.

"Although the straw grid is not an original sand control method in China, it is the most widely used here. After innovative improvements in terms of area coverage and method, the effect has also been enhanced," Wang said.

In Horqin Left Wing Rear Banner in the Inner Mongolia autonomous region, Wang pointed to a grassland where trees and shrubs grow and said, "Unlike planted forests, this area has naturally regenerated into a sparse woodland grassland landscape, which is a very healthy natural state."

Over the past decade, Wang has visited many sandy areas in Inner Mongolia, Liaoning and other regions, studying how tree density can form the healthiest ecosystem under different environments.

Dang and his team have also spent a considerable amount of time observing whether planting forests will cause a drop in the groundwater level and other sensitive issues related to afforestation.

"After more than 10 years of monitoring, we have concluded that the transpiration of Mongolian Scots pines accounts for approximately 42 percent of the local precipitation annually, reaching close to 60 percent in some years, but it has never exceeded 100 percent," Dang said. "Before, because people did not know how much water this tree species used for growth, some were concerned that it would deplete groundwater. However, scientific monitoring has overturned this conclusion."

He explained that the Mongolian Scots pine is highly drought-resistant, with over 85 percent of its fine roots concentrated within a depth range of 60 centimeters from the surface, which also means it does not consume a large amount of groundwater.

"One of the most important issues is how to allow the planted trees to naturally reproduce, so that the forests planted by humans for many years can naturally regenerate and continue, ensuring that these 'Green Great Walls' can protect our farmland and cities for generations to come, rather than having to replant them after 100 years," Dang said.