Variations in Growth, Clonal and Sexual Reproduction of Spartina alterniflora Responding to Changes in Clonal Integration and Sand Burial

Clonal plants can shift their allocation to growth, clonal, and sexual reproduction under different conditions. To test this hypothesis, a greenhouse experiment was conducted to explore the effects of sand burial degrees and clonal integration on the trade-offs among growth, clonal, and sexual reproduction in an invasive species, Spartina alterniflora. Ramets of connected genets to artificially disconnected ramets buried by sand to a depth of 0, 8, and 16 cm, respectively, were compared. Clonal integration stimulated the growth and clonal reproduction of daughter ramets, but has negative effects on these performances of mother ramets. Consequently, clonal integration had no effect on the clones. Biomass allocation to sexual reproduction in mother ramets and whole clones were stimulated by severing rhizomes. It could be concluded that the increased performances of daughter ramets occurred when mother ramets showed decreases of growth, clonal, and sexual reproduction when buried. Increased sexual reproduction in response to sand burial might represent a compensatory mechanism to reduced growth and clonal reproduction in S. alterniflora. Rhizome fragmentation did not influence growth and clonal reproduction, but increased sexual reproduction at the clone level.