https://www.sciencedirect.com/science/article/abs/pii/S0378112725000891?via%3Dihub

http://english.cas.cn/newsroom/research_news/earth/202503/t20250324_908616.shtml

Editor: ZHANG Nannan |  Mar 24, 2025

A breakthrough study using ground-penetrating radar (GPR) has identified the optimal planting density for Mongolia pine plantations in China’s arid regions, offering a science-backed solution to combat tree die-offs threatening anti-desertification efforts.

The research was conducted on a long‐term trial in Zhanggutai, Liaoning Province by the CAS Institute of Applied Ecology in order to identify the causes behind the mysterious decline of Mongolia pine (Pinus sylvestris var. mongolica) plantations—a cornerstone of China’s “Three-North Shelterbelt” reforestation project. The findings reveal that overcrowded tree stands lead to intense underground competition for water, accelerating forest degradation in semi-arid zones like the Horqin Sandy Land.

Mongolian pine was introduced in 1955 to combat desertification. However, after 35–40 years, many plantations began to decline, exhibiting symptoms such as leaf yellowing, weakened growth, and increased pest infestations. These issues have largely been attributed to high initial planting densities and insufficient thinning practices. Recognizing that survival in arid and semi-arid regions depends on root-mediated water and nutrient uptake, this study reconsiders stand density from a belowground perspective.

By using ground-penetrating radar, the researchers establishing quantitative relationships between stand density and root competition intensity indicators，the researchers identified the optimum stand density as being between 177 and 214 trees per hectare for 45-year-old plantations.