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Individual study: Effect of protection from livestock grazing on vegetation and plant succession in tall grass prairie of the Grassland Investigations Project, Oklahoma, USA

Published source details

Penfound W.T. (1964) The relation of grazing to plant succession in the tall grass prairie. Journal of Range Management, 17, 256-260


The effect of cessation of livestock grazing on vegetation composition and plant succession in previously moderately-grazed tallgrass prairie was investigated in the Grassland Investigations Project (McClain County), Oklahoma, south-central USA.

In 1949, four study plots were established: a protected (from livestock grazing) prairie (2 acres; 0.81 ha) and grazed prairie (20 acres; 8.1 ha) both dominated by little bluestem Andropogon(Schizachyrium) scoparium; and protected (5 acres; 2.0 ha) and grazed cropland (3 acres; 1.2 ha) planted with (non-native) Korean clover Kummerowia stipulacea in 1941, but allowed to ‘revert to natural conditions’ and dominated by it and prairie three-awn Aristida oligantha at the start of the experiment.

Prior to 1949, all plots had been moderately grazed for many years. Vegetation was sampled up to 1962. In each plot, autumn composition was determined within 25 (10 x 10 cm) quadrats, and frequency and foliage cover were calculated.

The number of species in quadrats was lower and declining in the ungrazed prairie (19 in 1964, 26 in 1954) whilst the grazed prairie remained little changed (29-31 species). Notable features of no grazing were a change from mid to tallgrass and rapid development of native woody prairie species, especially coralberry Symphoricarpos orbiculatus (2.6% cover in 1959, 15% in 1962), several forest shrubs were invading and there was an increase in mulch accumulation. There was also a marked decline of little bluestem (60.8% cover in 1954, 20.4% in 1962) whilst on the grazed prairie it remained fairly constant (26-31%).
On the ungrazed cropland little bluestem increased greatly (0.1% cover in 1950; 52.6% cover in 1962) as well as indiangrass (0.3 to 16.5%) and forbs declined. Composition of the grazed cropland changed from an annual grass stage to short grass and a midgrass type by 1962, similar to the grazed prairie.
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