Japan's coastal forest restoration programme is planting millions of Pinus thunbergii seedlings, creating living sea walls that will protect local communities from potential natural disasters.
Since the tsunami of 2011, millions of pine seedlings have been planted in Japan.
In Japan, the black pine has become one of the world's most promising natural barriers against potential tsunami damage, offering a natural (living) alternative to concrete walls. Pines, which are able to absorb waves and stabilise shorelines, are increasingly regarded as the foundation of protection for communities exposed to tsunami risk.
The Indian Ocean tsunami of 2004, in which 227,898 people across 14 countries were killed or went missing (90% of the world's tsunami fatalities between 1990 and 2024), exposed the vulnerability of coastal regions. As tsunamis, floods and earthquakes continue to wreak their destruction, research by Yokohama National University has confirmed the importance of the Japanese black pine (Pinus thunbergii) in mitigating the impact of disasters in Japan and South-East Asia.
The Japanese black pine is very well suited to forming a "living wall". Its root system reaches deep into the ground and is extensive enough to bind sandy soils and reduce erosion. Under the force of strong coastal winds the trunks bend rather than break, forming a living barrier that is highly resilient even during exceptionally severe storms. Researchers at Nagoya University have concluded that "the taller the Japanese black pines growing along the coast, the deeper their roots penetrate into the ground. Deeper roots make the trees more resistant to damage caused by tsunamis and strong winds."
Belts of mature, dense pine not only withstand storms but also reduce the force of waves. Acting as "permeable green walls", they slow the inrush of water before it reaches inland areas. "Black pines have been planted on Japan's beaches since ancient times because of their high resistance to strong winds and tsunamis, and because they reduce the effects of sea salt. These qualities are beneficial for mitigating the consequences of disasters in the event of tsunamis and severe storms," note the researchers at Yokohama National University.
Recent research rates the benefits highly
A study published in the Journal of Forest Research found that more densely planted forests, containing older trees with larger trunks, dissipate wave energy more effectively. The findings indicate that mature, well-established pine forests provide the strongest protection.
In 2025 a publication in the Journal of Forest noted that the positive effect is more considerable still. Improving the growing conditions of Pinus thunbergii — for example by improving drainage or loosening the soil around the seedlings — could encourage roots to grow deeper and strengthen their protective capacity. Mature trees already have the extensive root network needed to withstand the difficulties caused by a strong tide. In addition to tsunami protection, Japanese black pines adapt well to extreme climatic conditions. Thanks to their thick bark and their resin, which retains moisture, they also tolerate severe drought and salinity, and they are resistant even to small forest fires. After such disturbances Japanese black pines recover quickly, ensuring the continuity of these protective forests.
Further information: Hirano, Y., Todo, C., Tanikawa, T., Yamase, K., Ohashi, M., Dannoura, M., Okamoto, Y., Doi, R., Yoshida, G., & Ikeno, H. (2024). Intraspecific variation in root system structure in a Pinus thunbergii stand grown on a gravelly coastal dune. Journal of Forest Research, 1. https://doi.org/10.1080/13416979.2024.2431756