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Individual study: Effect of transplant size on establishment of prairie cordgrass Spartina pectinata in restoration of wet prairie near Somerset, Kansas, USA

Published source details

Fraser A. & Kindscher K. (2005) Spatial distribution of Spartina pectinata transplants to restore wet prairie. Restoration Ecology, 13, 144-151


Wet prairie dominated by prairie cordgrass Spartina pectinata was once widespread in swampy areas and along streams of central midwest USA. After European settlement, over 95% of this grassland community was converted to cropland. Restoration of wet prairies should include prairie cordgrass, but historic densities of this once dominant species are difficult to achieve. In this experiment, different cordgrass transplanting densities were trialled to assess which would most effectively provide good cover and density.

Study site: Trials were undertaken on a former agricultural field (17.4 ha, cultivated until 1998 when planted with a sorghum nurse-crop) on a floodplain near the town of Somerset, northeast Kansas. In April 1999 it was seeded with a native prairie grass and tallgrass prairie forb mix. The site was spring mown in 2000 and 2001.

Experimental design: In June 1999, cordgrass sods were planted as: 20 small plugs (each 20 cm diameter), four medium-sized plugs (46 cm diameter), or one large plug (91 cm diameter). Each had approximately the same initial cord grass area (0.6 m²) The small plug treatment required 160 person-hours to plant but no special equipment. The medium plugs required 120 person-hours, the large plugs 80 person-hours, but with both also requiring rental of a tree spade for 1 week (at $1,200/week).

Prairie cordgrass material was obtained within 100 km of the site and plugs were planted on the same day as collected. Each treatment was replicated in 20 plots. Five replicates per treatment were assigned to each of four microtopography elevation categories: 0–0.29 m; 0.30–0.58 m; 0.59–0.88 m; and 0.89–1.16 m, based on elevation above the lowest plot of the site. Treatments were assigned randomly to the plots. During the sampling period, the lowest elevation had standing water in spring and early summer, while the second lowest category had moist soil in spring and early summer. The two highest elevations had moist soils only following heavy rain.

Monitoring: The 500 plugs were surveyed in September 1999, 2000 and 2001. Stem density and height of restored cordgrass were compared to reference communities. As soil particle size and soil nitrogen can influence cordgrass stem density and height, these soil characteristics were determined.

Three years after transplanting, cordgrass had survived well in all plots regardless of plug size or planting elevation, with an overall survival rate of 89.8% in September 2001. Height did not vary among planting strategies, and field elevation did not affect area, stem density or height. The small plug treatment produced the greatest cordgrass area after 3 years (3.99 m²), compared with medium (1.18 m²) and large plugs (0.79 m²). However, stem density of small and medium plugs decreased dramatically during the sampling period (they tended to spreadout), whereas density of large plugs increased. Reference populations of cordgrass had greater stem density and height than the transplants, and these differences were not attributed to soil particle size or soil nitrogen.

Conclusions: This study indicates that at this restoration site, more than three years is needed to create a density or height of prairie cordgrass sward similar to established wet prairie populations.

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