Most of Nebraska's prairie ecoregion maps look like this.
Or this.
Most sources seem to agree that most or all of the grasslands west of the Sandhills and south of the Pine Ridge (in other words, the High Plains) are "shortgrass prairie." Shortgrass prairie is defined by the Nebraska Natural Legacy project as being "... dominated by short statured grasses such as buffalograss, blue grama, sideouts grama, and purple threeawn. ... The low precipitation in the shortgrass prairie ecoregion, in conjunction with grazing causes, [sic] most shortgrass vegetation to rarely exceed 10 inches in height." This is a tidy way to classify Nebraska's High Plains prairies, but, as will be revealed below, not entirely true.
Enter
Terrestrial Ecological Systems and Natural Communitese of Nebraska, Version IV, by Steve B Rolfsmeier and Gerry Steinauer.
I got this awesome publication about a month ago. It defines the 19 ecological systems and 83 natural communities found in Nebraska and goes into great detail on all of them, including ranges, environmental descriptions, vegetation descriptions, invasive species of concern, and several other topics. Most of their classification correlates with what other sources have classified, with one major exception:
they changed the name of the universally-accepted "Western Great Plains Short-grass Prairie" to "Western Great Plains Mixed-grass Prairie." Basically, they're ditching the term "shortgrass prairie." Here's why:
"For many years, biogeographers and ecologists unfamiliar with the region have classified the High Plains of western Nebraska as a region of "short-grass prairie," as the global name for this ecosystem reflects. Short-grass prairie is defined as dominated by blue grama with other short and mid-height grasses playing a secondary role. In Nebraska, areas of short-grass prairie have been recorded, but always as a patches [sic] occuring within a mixed-grass prairie setting, apparently the result of localized heavy grazing. These sites tend to revert to mixed-grass prairie once grazing pressure is diminished. Prairie in the northern High Plains of Nebraska tends to be dominated by cool-season graminoids, with blue grama playing a supporting role (except where increasing under heavy grazing), so the inclusion of this area in a system dominated by warm-season grasses seems problematic. "Short-grass prairie" was recognized as an accepted community in previous editions of this classification, but its occurrence as a patch type within several other mixed-grass prairie communities (usually Threadleaf Sedge Mixed-grass Prairie but also Loess Mixed-grass Prairie, Sandhills Dry Valley Prairie, and Northwestern Mixed-grass Prairie) indicates that in Nebraska it exists only as a temporary condition caused by livestock or herbivore grazing (though in some cases grassland associated with dense clays in extreme northwest Nebraska may be naturally-occurring shortgrass type, albeit limited in distribution."
So, assuming that the above is true (which I have no doubt that it is), it seems like "shortgrass prairie" should be out of the picture in terms of Nebraska's ecoregions, being replaced with "mixed-grass prairie"—more specifically, "Western Great Plains Mixed-grass Prairie."
Some Western Great Plains Mixed-grass Prairie in central Sioux County in late June.
