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| Many researches demostrated there is a strong relationship between phenotypic plasticity and plant invasiveness, especially in a frequently disturbed environments. In order to reveal the phenotypic plasticity and reproductive traits of the invasive species, Spartina alterniflora, along an elevation gradient in the salt marsh of Jiangsu Province, Chian, five parallel sample zones were set from the seaward to the upland with a small scale elevation gradient, and the environmental factors, growth and photosynthetic parameters of Spartina alterniflora were surveyed. The results show that there are significant differences for four environmental factors (pH, salinity, organic matter and available nitrogen) and some growth parameters among five sample zones. The changes of salinity, organic matter and available nitrogen are in verse, and they show a bell-shaped. Plant phenotypic parameters show a similar variation as that of salinity along the elevation gradient. The sexual reproductive traits (the ratio of reproductive stem to vegetative stem, spike length, seed set and germination rate) in the seaward are significantly lower than that in other sample zones, however, the number of buds reproduced from rhizomes was the most among that of five zones. The rate of rhizome allocation (as an indicator of clonal reproduction) is highest, and the rate of spike allocation (an indicator of sexual reproduction) is the least in the seaward population among that of all zones. In addition, there is a positive feedback relationship between growth of S. alterniflora and soil nutrition (organic matter and total nitrogen). The results indicate that the invasive species S. alterniflora represents a strong phenotypic plasticity even though along a small elevation gradient in the saltmarsh, and this plasticity and the trade-off between sexual and clonal reproductive strategies may be of significant importance for the invasion and outbreak of S. alterniflora. |
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| Keywords:population ecology；Spartina alterniflora; biological invasion; elevation gradient; phenotypic plasticity |
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