Habitat choice and seed–seedling conflict of Spartina alterniflora on the coast of China
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To elucidate the seed–seedling conflict and the process of habitat choices during the expansion of S. alterniflora, densities of seeds and seedlings in three different habitats, foreland, Spartina meadow, and canopy gap patch, were measured. Statistical analyses of these measurements were performed to investigate the interaction between seeds or seedlings and environmental factors. Also, the process of habitat choice during the expansion of S. alterniflora was explored. The results show that, in the upper soil seed bank (0–5 cm), both the ratio of germinated seeds and the ratio of survival seedlings to total seeds do not differ significantly among the three habitats. However, in the lower soil seed bank (5–10 cm), these ratios differ significantly, suggesting the seed–seedling conflict of S. alterniflora generally occurs in the lower soil seed bank. The remarkable conflict occurs in the meadow habitat. Greenhouse experiments indicate that the germination rate decreases significantly and the mortality of pre-emerged seedlings increases significantly with increasing burial depth. The maximal burial depth of emerged seedlings varies with sediment types. Comparisons of burial depth effects on seedling height, mesocotyl length, coleoptile length, and root length show that the major responses of S. alterniflora pre-emerged seedlings to the burial treatments are the elongation of coleoptiles and mesocotyls, which favor seedling survival by enhancing aeration and accelerating emergence. These results suggest that burial treatment is a key selection factor, which leads to the seed–seedling conflict in recruitment of S. alterniflora population, and directly affects the expansion rate and the area infected by S. alterniflora.
KeywordsHabitat choice Seed–seedling conflict Burial Sediment dynamic Invasion
Funded by Public Project of State Forestry Administration of China (200804005). Doctor Degree Fund of Ministry of Education (20070284022), Natural Scientific Foundation of Nantong University (07Z03, 08ZY001) and Research Foundation for Doctors of Nantong University (08B12). We wish to thank Prof. Liu Hong and Prof. Javier Francisco-Ortega at Florida International University for the constructive suggestion on an earlier draft of this manuscript. Special thanks to Dr. Heath de la Girody, writing and study skills advisor of University of Northern British Columbia, Canada for improving language.
- Deng, Z. F., S. Q. An, Y. B. Zhi, C. F. Zhou, L. Chen, C. J. Zhao, S. B. Fang & H. L. Li, 2006. Preliminary studies on invasive model and outbreak mechanism of exotic species, Spartina alterniflora Loisel. Acta Ecologica Sinica 26: 2678–2686.Google Scholar
- Du, R. Q., 1999. Biostatistics. China Higher Education Press, Beijing.Google Scholar
- Fenner, M., 1985. Seed Ecology. Chapman and Hall, London.Google Scholar
- Hedge, P., L. K. Kriwoken & K. Patten, 2003. A review of Spartina management in Washington State, US. Journal of Aquatic Plant Management 41: 82–90.Google Scholar
- Kennedy, R. A., S. C. H. Barrett, D. Vanderzee & M. E. Rumpho, 1980. Germination and seedling growth under anaerobic conditions in Echinochloa crusgalli (barnyard grass). Plant, Cell and Environment 4: 243–248.Google Scholar
- Kitajima, K. & M. Fenner, 2000. Ecology of seedling regeneration. In Fenner, M. (ed.), Seeds the ecology of regeneration in plant communities, 2nd ed. CABI publishing, London, UK: 331–396.Google Scholar
- Qin, P., M. D. Jin & M. Xie, 1985. Community biomass among the three ecotypes of S. alterniflora in Luoyuan Bay, Fujian. Journal of Nanjing University Special Issue 22: 6–236.Google Scholar
- Sun, S. C., X. B. Zhu & C. Q. Lü, 2004. Function assessment and ecological controls on alien species cordgrass. Chinese Journal of Ecology 23(3): 93–98.Google Scholar
- Wijte, A. H. B. M. & J. L. Gallagher, 1996a. Effect of oxygen availability and salinity on early life history stages of salt marsh plants. I. Different germination strategies of Spartina alterniflora and Phragmites australis (Poaceae). American Journal of Botany 83(10): 1337–1342.CrossRefGoogle Scholar
- Wijte, A. H. B. M. & J. L. Gallagher, 1996b. Effect of oxygen availability and salinity on early life history stages of salt marsh plants. II. Early seedling development advantage of Spartina alterniflora over Phragmites australis (Poaceae). American Journal of Botany 83(10): 1343–1350.CrossRefGoogle Scholar