Oesterheld M, Sala O E, McNaughton S J
Departamento de Ecología, Facultad de Agronomía, Universidad de Buenos Aires, Argentina.
Nature. 1992 Mar 19;356(6366):234-6. doi: 10.1038/356234a0.
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.
食草动物营养级的所有重要属性，包括生物量、消耗量和生产力，在广泛的陆地生态系统中都与初级生产力显著相关。我们在此表明，在南美洲农业生态系统中，初级生产力相差25倍的情况下，牲畜生物量与未管理生态系统呈现出斜率基本相同但y轴截距显著更大的关系。因此，对于给定的初级生产水平，农业生态系统中每单位初级生产力所支撑的食草动物生物量比自然生态系统中大约高一个数量级。我们还提供了证据表明，牲畜体型随初级生产力增加，这是之前在自然生态系统中所描述的一种模式。据我们所知，这是在区域尺度上首次对放牧、选种和兽医护理等畜牧实践对牲畜群生物量和体型结构的影响进行定量记录，并与本地食草动物进行比较。
