Leaf and tiller or stolon death of Lolium perenne, Agrostis spp., and Trifolium repens in set‐stocked and rotationally grazed hill pastures

Leaf death rates, leaf longevity, and tiller and stolon death rates of Lolium perenne , Agrostis spp. and Trifolium repens were compared for one year on hill pastures which were set‐stocked and rotationally grazed by sheep. Leaf death rates and leaf longevity were largely unaffected by grazing management, and the number oflive leaves per tiller or stolon did not differ greatly between managements. Agrostis spp. had more leaves per tiller than L. perenne . Leaf longevity was least in spring and summer when leaf death rates were fastest, and was greatest in winter when leaf death rates were slowest. In autumn, spring, and summer, mortality of leaves occurred within 3 weeks of their appearance, resulting in the loss of up to 28% of leaves which had been formed soon after one grazing before the next grazing under the rotational management. The long rotation in winter (63 days) resulted in the death of many leaves before they had a chance to be grazed. Leaf utilisation data showed that 20–46% of L. perenne leaf tissue, 45–63% of Agrostis spp. leaf tissue, and 34–60% of T. repens leaf production was ungrazed and subsequently died and decayed. Grazing pressure is critical in determining the amount of leaf tissue entering the litter pool, and has a considerable influence on tiller and stolon death.