Protecting prairie remnants with adjacent planted prairies

This interesting research was carried out at Nature Conservancy natural areas in four States: Loess Hills (Iowa); Glacial Ridge (Minnesota); Nachusa Grasslands (Illinois); and Kankakee Sands (Indiana). In all of these sites, prairie remnants existed embedded within extensive cropland that had been partly planted to prairie. Thus, remnant--restoration pairs existed, permitting a quantitative measure of impact of the planted prairie on the adjacent native prairie. The hypothesis was that resistance to invasion and the richness of the native flora would be greatest next to prairie restorations (planted prairies). Adjacent cropland, and roadsides would be progressively less effective or ineffective in protecting adjacent remnants.

The experimental design involved laying transects from the edges of the prairies to the center, and sampling at defined intervals.

It was found that nonnative dominance was higher at the edges than in the interiors of prairies adjacent to crops and to roadsides, whereas in prairies adjacent to restorations there was no edge effect on nonnative cover (see Figure).

Nonnative dominance from the edge to the center of prairie
remnants for different types of adjacent vegetation.

The implications of this study are clear. Prairie remnants standing alone or adjacent to roadsides or crop fields have much greater chance for invasion by nonnative species. Adjacent restorations can protect remnants against invasion.

Many prairie remnants are adjacent to ag fields which are suitable for planting to prairie. Since planting prairies is a relatively inexpensive activity, these data provide strong encouragement to carry out such plantings.

A further point: when prairie remnants are being acquired as part of land acquisition programs, high priority should be given to sites with extensive adjacent cropland or old fields suitable for prairie planting.

Here is the citation of this paper: Rowe, Helen; Fargione, Joseph; Holland, Jeffrey D. 2013. Prairie Restorations can Protect Remnant Tallgrass Prairie Plant Communities. American Midland Naturalist Vol. 170 (1): 26-38.

A prairie remnant (Black Earth Rettenmund Prairie) surrounded by ag fields and roads. An undesirable long-term situation?