A study was made of the effects of clipping on yield and tillering of three important native grasses, little bluestem Andropogon scoparius, big bluestem A.gerardi and indiangrassSorghastrum nutans in natural prairie-like glade grassland in the Ozarks of southwest Missouri (USA). This region is the transition zone between eastern oak-hickory forest and the southeastern fringe of the Tall Grass Prairie.
One of seven clipping treatments (several stages of plant development through the growing season) repeated over three years (1961-1963) were randomly assigned (randomized block design) to 12 plants per treatment of little bluestem, big bluestem and indiangrass in habitat ungrazed by livestock for 5 years. Approximate clip dates were: 20-30 May; 25-30 June; 20-25 July; 25 August-5 September; 1-10 October; and 15 November.
In the winter before treatment application, dead foliage from each study plant and vegetation within an area of about 0.4 m² was removed (to 4 cm above ground level). Yields of non-clipped (control) plants and regrowth of clipped study plants were estimated at the end of the growing season (dry weight). Tillers were counted just before the first clipping in May. Reproductive and vegetative culms were counted and their length (height) measured either on the day of clipping or at the end of the growing season.
Yields of all three grasses increased when clipped for 3 consecutive years in late autumn (November) when dormant and spring tillering was encouraged. When clipped after seed formation (October) little and big bluestem also responded by increasing yields but indiangrass yield was reduced and was similar to (slightly less) that of the unclipped controls.
Yields of all three species when clipped at earlier stages of plant development in spring and summer (May-August), or not clipped, were less than that of plants clipped in October or November. Clipping when flowering stalks were forming (late July) was the most damaging treatment to all three grasses, and yields declined from the second to third year.
These results suggest that autumn and winter grazing is best for glade range management.