Spatial Distribution of Spartina pectinata Transplants to Restore Wet Prairie

Restoration of wet prairie in the central midwestern United States should include Prairie cordgrass (Spartina pectinata), but historic densities of this once dominant species are not easily achieved. Spartina pectinata was transplanted into a former agricultural field in three planting strategies: 20 small plugs, 4 medium-sized plugs, and a single large plug, with each treatment area totaling 0.6 m. Plugs were sampled annually for 3 years to determine which planting strategy produced highest survival, area, stem density (per unit vegetated area), and height of S. pectinata It was also determined whether these factors varied with microtopography, and the resulting differences in flooding, within the restoration site. Stem density and height of restored S. pectinata were also compared to reference S. pectinata communities, including both pristine populations and the source of transplants. Because soil particle size and soil nitrogen content can influence S. pectinata stem density and height, these soil characteristics were also tested in restored and reference sites. Three years after planting, S. pectinata survived in all planted plots regardless of planting strategy or microtopography, with an overall survival rate of 89.8% at the end of the study. The small plug treatment produced the greatest area after 3 years (3.99 m), compared with the final area of medium (1.18 m) and large plug treatments (0.79 m). Stem density of small and medium plugs decreased dramatically during the sampling period, whereas density of large plugs increased. Height did not vary among planting strategies, and microtopography did not affect area, stem density, or height. Reference populations of S. pectinata had greater stem density and height than the transplanted plugs in the restoration, and these differences cannot be attributed to soil particle size or soil nitrogen. This study indicates that more than 3 years is needed to create area, density, or height of S. pectinata similar to established wet prairie populations. Planting many small plugs yields the greatest area of S. pectinata, and including some large plugs may add dense physical structure to wet prairie restoration.