Persistence of native C4 grasses under high-intensity, short-duration summer bison grazing in the eastern tallgrass prairie

Published source details Jackson R.D., Paine L.K. & Woodis J.E. (2010) Persistence of native C4 grasses under high-intensity, short-duration summer bison grazing in the eastern tallgrass prairie. Restoration Ecology, 18, 65-73.
Share Tweet Email

Summary

Using livestock grazing to manage restored prairie has been seldom investigated. A study was undertaken to assess response of native warm-season (C4) grasses under high-intensity, short-duration summer bison Bison bison grazing in eastern tallgrass prairie at Bison Ridge Ranch (43°45′11″N, 89°27′6″W), Wisconsin, north-central USA.

In 1998, six stands of C4 eastern tallgrass prairie grass species were established (randomized complete block design, three blocks) on former arable cropland. Treatments were drill-seeding (10 kg seeds/ha) into tilled bare soil of: single species of C4 grasses (big bluestem Andropogon gerardii, switchgrass Panicum virgatum, Indiangrass Sorghastrum nutans, little bluestem Schizachyrium scoparium and sideoats grama Bouteloua curtipendula),and a mixture of these excluding switchgrass.

Starting in 2001, bison (75-100 head) were rotated through four 0.5-ha sown paddocks for about 2 days each, two or three times annually (late June, July, early August) to achieve a stubble height of 5-10 cm.

During 2000-2006, cover was estimated in randomly placed quadrats (12 to 21 days after each grazing event in each year) of four plant functional groups (C4 grasses, cool-season (C3) grasses, non-leguminous forbs, and legumes) and C4 species.

An expected decline in C4 grass cover over the 6-years occurred (bison preferentially eat C4 grasses). However, their rapid decline, given very high C4 cover and minimal cover of other functional groups in all treatments following seeding (1999-2001) was unexpected. C4 cover declined at different rates depending on species. Switchgrass decline was slowest, big bluestem, Indiangrass and sideoats grama (rates of decline similar) next; little bluestem declined most rapidly.

As C4 grasses declined soil was exposed, with rapid colonization by C3 species (probably aided by soil seed banks and seed rain from adjacent fields supporting C3 species). Annual grasses initially colonized the bare soil created by grazing, followed by legumes. Although warm-season grasses were still the dominant functional group 8 years after seeding, colonization by non-native cool-season forage grasses increased over time, replacing legumes.

Note: If using or referring to this published study, please read and quote the original paper, this can be viewed at: http://onlinelibrary.wiley.com/doi/10.1111/j.1526-100X.2008.00439.x/full