Grazing and net primary production of a temperate grassland.
Measurements were made of CO2 exchange by sods taken from a Phalaris tuberosa/Trifolium repens temperate grassland to determine their net primary production when grazed by Merino sheep at 3 different stocking densities. Net primary production over 48 weeks was greatest at 20 sheep/ha and least at 10 sheep/ ha; at 30 sheep/ha it was slightly greater than at 10 sheep/ha. The seasonal pattern of net primary production was similar at all stocking densities, but stocking density differentially influenced the seasonal levels. These seasonal fluctuations in net primary production were greatest at 30 sheep/ha and least at 10 sheep/ha. The data suggested that there was an optimum stocking density for maximum net primary production of grazed temperate grasslands, but this varied with time of year.