An accidental geoengineer
In December 1979, scientists intentionally introduced a foreign grass to China's coast. The plant, smooth cordgrass (Spartina alterniflora), is native to the Atlantic coast of the Americas. The hope was that this salt-tolerant plant would protect coastlines from erosion and help build up new land on the vast tidal flats. It worked far better than anyone anticipated. The grass is a powerful "ecosystem engineer," physically altering its environment. Its dense stems, which can grow up to two meters tall with up to 200 stalks per square meter, slow down tidal currents. This causes suspended sediment to fall out of the water and accumulate. Its extensive underground root systems, or rhizomes, then bind the new mud, raising the elevation of the marsh.
This process dramatically accelerates coastal accretion. In some areas, marshes dominated by S. alterniflora have advanced seaward by nearly a kilometer in just nine years. This rapid land creation transforms the very geography of the coast, turning open mudflats into dense grasslands. By 2015, the grass had expanded to cover over 50,000 hectares along China's coast. The process is pronounced in the Yellow River Delta, which is part of the Shandong Peninsula's coastal system. The river deposits enormous quantities of sediment naturally, and the introduction of S. alterniflora has amplified this effect.