Eradicating invasive Spartina alterniflora with alien Sonneratia apetala and its implications for invasion controls

The smooth cordgrass (Spartina alterniflora) has invaded coastal areas throughout the world, including China, in the past decades. Scientists of China and other countries are trying all means to control its invasion, including physical removal, chemicals, and biological control by herbivores. The present research chose a small island (the Qi'ao Island) to study biocontrol of S.alterniflora with mangroves. In 1999, we began to introduce fast-growing mangroves (mainly an alien species, Sonneratia apetala) to control S. alterniflora invasion. In 2011, we eventually eradicated S. alterniflora (only 0.63 ha remained for experimental purpose) through expanding mangroves up to 300 ha. The dozen-year monitoring showed that S. apetala did not invade in native mangroves. The isolated island in the present study makes an experiment platform for scientists to find a strategy to check one invasive plant with another alien plant but not introducing new invasions.