EARLY-19TH-CENTURY GRASSLANDS OF THE MIDCONTINENT PLAINS

The abundance patterns of native grasses in the Midcontinent Plains may be examined through several lines of evidence, but the patterns are often contradictory. The journals of scientific exploration, early maps of grass cover, contemporary data, and paleobotanical materials in the form of opal phytoliths are examined to resolve the discrepancies among the various sources. The most significant discrepancy is the lack of convergence of evidence on the eastern limit of the shortgrass dominance in the Central Plains. When all data are placed in a temporal context, the emergent pattern of disagreement over the location of the eastern margin of shortgrass dominance suggests a continual westward movement of the boundary between the tall and short, warm-season grasses in the Central Plains. Since the Little Ice Age, the westward movement of tall, warm-season grasses that emerges from the data suggests that climate does not determine grass patterns, and that the vegetation cover of the early nineteenth-century would not pertain today, even in the absence of massive human intervention. The strong role of stochastic processes is not rejected.