Northern Tallgrass Prairie

This system is found primarily in the Northern Tallgrass ecoregion ranging along the Red River basin in Minnesota and the Dakotas to Lake Manitoba in Canada. It constitutes the northernmost extension of the "true" prairies. Similar to Central Tallgrass Prairie (CES205.683), this system is dominated by tallgrass species such as Andropogon gerardii, Sorghastrum nutans, and Panicum virgatum. However, the soils in this region are not as rich nor deep, the growing season length and precipitation are less, and thus this system does not have as much species diversity as grasslands to the south. This system is often found on well-drained, drier soils and can grade into Eastern Great Plains Tallgrass Aspen Parkland (CES205.688) to the north and east. Grazing and fire influenced this system historically. Much of this system has been converted to agriculture with very few unaltered and highly fragmented examples remaining.

Fire plays an important role in the maintenance of this prairie system (Curtis 1959, Vogl 1964, Anderson 1990b). Fire promotes seed production and flowering necessary for plant regeneration. Because environmental conditions are suitable for tree growth, without recurrent fire (every 2-10 years), succession to forest or woodland will occur rapidly (Minnesota DNR 2005b). From Landfire BpS: Frequent fires impacted this prairie system every 1-3 years, maintaining grass and forb vegetation. Fire could occur throughout the year with larger, less frequent fires occurring during the dormant season and smaller, more frequent fires occurring during the growing season. Native American burning, essential to maintaining the eastern tallgrass prairie, was bimodal in distribution, peaking in April and October with lightning ignition occurring primarily during July and August (Higgins 1986).

Bison grazing as a major disturbance was likely much more limited than prairies further west. Elk probably contributed to the impact of grazing and browsing as well, but it is assumed that the total contributions of these two species was still considerably less than to the west. The elk may have contributed to the reduction of young woody saplings invading prairie adjacent to protected woody areas. Prior to European settlement, episodic grazing by large, native mammals was common and encouraged the persistence of several native grass and forb species (Minnesota DNR 2005b). Insect and small mammal herbivory impacts composition and dominance. From Landfire BpS: Bison, with peripheral help from grasshoppers, elk, antelope and a myriad of smaller animals made herbivory one of the dominating factors of the northern tallgrass prairie (Severson and Sieg 2006). With estimates of 30-60 million bison in the Northern Great Plains (Isenberg 2000), herbivory by large mammals also was a significant disturbance to the grasslands. Bison herbivory occurred in a mob-grazing or flash-grazing method, with extensive herds migrating across the prairie as they graze. Modern rotational grazing systems simulate this by resting areas after intensive grazing. Elk, too, may have played an important role than generally believed, particularly in the eastern portion of the zone. Whether bison or elk, large mammals preferentially grazed recently burned sites.

The northern tallgrass system has been significantly transformed since European settlement largely into an agricultural landscape. Remaining patches are highly fragmented. Woodland acreage has increased appreciably due to fire suppression, extirpation of native grazers, and human disturbance. Many areas that were not cultivated are subject to intensive grazing which has resulted in most native species being replaced by introduced ones (Minnesota DNR 2005b). Without heavy intervention and intense management and restoration efforts, it is highly unlikely that many remaining northern tallgrass prairie patches will be self-sustaining or persist over time (Koper et al. 2010).

Found primarily in the Northern Tallgrass ecoregion ranging along the Red River basin in Minnesota and the Dakotas to Lake Manitoba in Canada.