The Seasonal Contribution of C"3 and C"4 Plant Species to Primary Production in a Mixed Prairie

Ode, David J.; Tieszen, Larry L.; Lerman, Juan Carlos

The Seasonal Contribution of C"3 and C"4 Plant Species to Primary Production in a Mixed Prairie

1980

Ode, David J. | Tieszen, Larry L. | Lerman, Juan Carlos

A Mixed Prairie in the Northern Great Plains (South Dakota, USA) was studied to determine the floristic composition, according to C₃ and C₄ types, of the seasonal contribution to aboveground production. Twenty—seven of the 305 species present in the Ordway Prairia possessed Kranz anatomy and are assumed to be C₄. Thirty—six percent (19) of the grasses were C₄ whereas <2% (4) of dicots were C₄. Dicots were often weedy and fugitive or introduced species. C₃ plants possessed a mean °¹ ³C value of —26.7%, C₄ plants a value of —12.9%. The biomass of lowland and upland communities possessed low °¹ ³C values in spring. These values increased significantly in the upland community in midsummer to —20.0% indicating a shift to C₄ activity. In fall the biomass °¹ ³C values were again low in both communities indicating a return to C₃ activity. These data show a clear seasonal displacement in production activity of C₃ and C₄ grasses in the Mixed Prairie. A general discussion of the evolution and significance of photosynthetic pathways is included.

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