Experimental wrack disturbance at four times during the growing season

Using a field experiment on the Georgia coast, we simulated the effects of wrack disturbance on the marsh grass Spartina alterniflora. We simulated wrack disturbance on four different dates by covering selected plot with 10 cm of wrack collected nearby on March 18, May 27, July 15 or September 7. Wrack was fixed to the marsh surface with string so that it could not wash away. We also simulated the mechanical disturbance created by wrack but without the input of organic matter by clipping selected plots at the soil surface on the same dates. We measured plant heights in a 50 cm×50 cm quadrat centered in each plot before the first treatments were conducted in March, again on May 9, and every two weeks thereafter until plots were harvested. We also recorded the status of flowering in the late of the growing season.The center 50 × 50 cm of each plot was harvested by clipping stems at the soil surface on October 5-6, 2015. We measured the height and flowering status of each stem, and counted the number of stem-boring insects present in each stem by splitting the stem open. Data include plant height, flowering status and stem bored status.