Animal modification of native vegetation: Modification of grasslands by grazing animals

[First paragraph...]
Martin Jones (1933), working on high producing pastures in Great Britain, found that heavy grazing or close cutting resulted in a reduction of the root weights of the major species (ryegrass, cocks foot, timothy, red and white clovers). By altering the time of early spring grazing, the species composition of pastures could be changed. Grazing, when one of the species was commencing growth and its level of food reserves was at its lowest point, weakened that species as a competitor in the sward. Thus, in the production of clover seed in New Zealand, the planned heavy grazing of ryegrass/white clover pastures in spring, when growth of ryegrass is just beginning, results in dominance of the pasture by white clover, which starts spring growth later.