Population expansion of invasive plant Spartina alterniflora in the Tianjin coastal wetland, China

Since the introduction to Tianjin coastal area, Spartina alterniflora growed and adapted well to the local environment. According to the distribution patterns, we divided the S. alterniflora population into `patch´ and `blanket´. We investigated the spread process of the patch population. We also studied the seasonal dynamics of two types of S. alterniflora population, including the density, height, aboveground biomass and F/C value. The results showed that in the past growing season, the patch population expansion speed parallel to the shoreline (42~92%) was larger than the speed vertical to the shoreline (39~62%). The population density increased to 322.19 ramets·m^-2 (patch) and 763.33 ramets·m^-2 (blanket) at the end of the growing season. The aboveground biomass reached peak values at 2453.57 g·m^-2 for patch population and 5085.68 g·m^-2 for blanket population 170 days after returning green. The F/C value decreased through the growing season. The blanket population had higher density, more aboveground biomass and lower F/C value than the patch population. But there was no significant difference between the heights of the two patterns population.