Effect of animal husbandry on herbivore-carrying capacity at a regional scale.
All significant properties of the herbivore trophic level, including biomass, consumption and productivity, are significantly correlated with primary productivity across a broad range of terrestrial ecosystems. Here we show that livestock biomass in South American agricultural ecosystems across a 25-fold gradient of primary productivity exhibited a relationship with a slope essentially identical to unmanaged ecosystems, but with a substantially greater y-intercept. Therefore the biomass of herbivores supported per unit of primary productivity is about an order of magnitude greater in agricultural than in natural ecosystems, for a given level of primary production. We also present evidence of an increase in livestock body size with primary productivity, a pattern previously characterized in natural ecosystems. To our knowledge this is the first quantitative documentation at a regional scale of the impact of animal husbandry practices, such as herding, stock selection and veterinary care, on the biomass and size-structure of livestock herds compared with native herbivores.
Oesterheld
M
M
Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
Sala
O E
OE
McNaughton
S J
SJ
D000383:Agriculture; D000821:Animal Feed; D000822:Animal Husbandry; D000818:Animals; D001118:Argentina; D002417:Cattle; D004463:Ecology; D006109:Poaceae; D012756:Sheep; D014583:Uruguay