|Geomorphic zones have been recognized in the|
Black Hills since the time of Darton (1909).
Arrow points to the gently-dipping Limestone Plateau.
Large grasslands are common at higher elevations in the western Black Hills, on the Limestone Plateau and adjacent Central Core. Recent survey found that most are dominated by non-native species, especially the hay grasses timothy and smooth brome. Native grasslands are restricted to the drier southern part of the study area where Prairie Dropseed - Richardson's Needlegrass - Timber Oatgrass Herbaceous Vegetation (more often called Black Hills montane grassland) occupies broad drainage bottoms and adjacent lower slopes. This vegetation type is endemic to the Black Hills and has suffered major decline with human settlement.
Ecological integrity (condition, quality) of grasslands was assessed using metrics specific to Black Hills montane grassland vegetation. Native plant cover, presence of invasive exotic species, cover of native increaser species and soil surface condition were assessed in the field. An overall condition rank was calculated from the four individual metric ranks. Size and landscape context were evaluated utilizing remote sensing (aerial photography). Condition, size and landscape context ranks were then combined to produce an ecological integrity rank for each grassland.
|Reynolds Prairie looking east from Flag Mountain; high granite region of the|
Central Core visible in the distance. Most of these grasses are non-native hay species.
Of the 99 grasslands assessed, only seven ranked highly. The most significant down-ranking factor was abundance of non-native species. All high-ranking montane grasslands are located within a 40 sq mi area in the southern part of the Limestone Plateau, on public lands managed for multiple-use. The best stands occur in drainages with little or no water development for livestock.
|Large native montane grassland in West Hell Canyon, happy botanist for scale.|