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Prairie Terraces

Ecoregion in OR

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The nearly level to undulating Prairie Terraces ecoregion includes all of the terraces of the Willamette River upstream of the Portland/Vancouver Basin (3a). Ecoregion 3c is drained by low-gradient, meandering streams and rivers. Its broad fluvial terraces once supported oak savanna and prairies that were maintained by burning; wetter areas supported Oregon ash and black cottonwood. Today, only relict native prairie remain. The poorly drained soils derived from glacio-lacustrine deposits are extensively farmed for grass seed and small grains. Grasses tolerate poor drainage and poor rooting conditions better than other crops. In addition to agriculture, the Prairie Terraces also experience the bulk of urban expansion.

— EPA

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Ecoregion