Spartina Cordgrass Jiangsu Coastal Indigenous Plants Relative Competitiveness Study

Spartina alterniflora originates in east coast of North America, and acts as the native dominant species in the salt marshes. Because of its high tolerance to environment and high capacity of dispersal, S. alterniflora was introduced to China in 1979 tu accelerate the sedimentation. It has played some roles in maintaining the coastlines, but in recent years, S. alterniflora has been found to be harmful to the intertidal ecosystems in southern provinces of China because of its high invasive ability. S. alterniflora was introduced several times to coastal wetlands of north Jiangsu, and now it is one of the greatest threats to the local wetland ecosystem. Dispersal monitoring and field competition experiments were employed to understand the Relative competitive ability of S. alterniflora and native species of coastal wetlands, and to propose suggestions of its control.1.In the course of competition between native species and S. alterniflora tiller, S. alterniflora tiller can significantly inhibit the growth of native species and S. alterniflora tiller and native species were allocated more energy to the roots, so S. alterniflora tiller compete with native species, which was mainly concentrated in the ground for moisture and nutrients. On reed area and ecotone, sexual reproduction is the main reproductive modes of S. alterniflora tiller. Large numbers, small size and easy germination of S. alterniflora seeds made S. alterniflora has invasive spread so that it had more opportunities to find suitable habitat. On Suaeda area and ecotone, S. alterniflora seedling could not survive.2.S. alterniflora could change the environment more effective than Suaeda, reeds. Root system of S. alterniflora could increase soil water content and reduce salt stress because of its salt resistance and characters of ions secretion. On ecotone, S.alterniflora and Saudea relative competitiveness was 1.94±0.94, S.alterniflora's competitive ability is stronger than Saudea's; On Suaeda area, S.alterniflora and Saudea relative competitive ability was 0.87±0.30, S.alterniflor and Saudea's competitive ability was relative balance. Therefore, Saudea and reed may be eroded by competition between species habitat salsa and are replaced by S.alterniflora.3. The results showed that, S. alterniflora invaded into Saudea mainly by seedling and kept the stability of population mainly by tiller. Soil water content and salinity of Saudea area were the better medium for S. alterniflora's establishment and expansion. Then, Saudea could be replaced by S. alterniflora and reed.