Effects of animal husbandry on secondary production and trophic efficiency at a regional scale

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Agricultural systems are expected to have higher net secondary production [NSP] than natural systems as a result of higher trophic efficiency and lower interannual variability. These differences, however, have not been quantified across regional gradients. We compiled a dataset of herbivore biomass,...

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Detalles Bibliográficos
Otros Autores: Irisarri, Jorge Gonzalo Nicolás, Oesterheld, Martín, Golluscio, Rodolfo Angel, Paruelo, José María
Formato: Artículo
Lenguaje:Inglés
Materias:
ABOVEGROUND NET PRIMARY PRODUCTION
HERBIVORES
POIKILOTHERM
HOMEOTHERM
INTERANNUAL VARIATION
CONSUMPTION
Acceso en línea:http://ri.agro.uba.ar/files/intranet/articulo/2014irisarri.pdf
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Biblioteca Central (FAUBA) de Universidad de Buenos Aires
Descripción
Sumario:Agricultural systems are expected to have higher net secondary production [NSP] than natural systems as a result of higher trophic efficiency and lower interannual variability. These differences, however, have not been quantified across regional gradients. We compiled a dataset of herbivore biomass, consumption, NSP, annual precipitation, and aboveground net primary production [ANPP] for extensive livestock farms across a wide precipitation gradient in Argentina. We compared these data with worldwide published studies of natural systems. In a double-logarithmic scale, NSP of agricultural systems increased with ANPP from semiarid to subhumid systems and decreased from subhumid to humid systems, a response that contrasted with the linear positive increase of natural systems. Compared to natural systems dominated by homeotherms, Etroph [NSP:ANPP] in agricultural systems in semiarid areas was 8 times higher, due to a 2 times higher Econsump [Consumption:ANPP] and a 4 times higher Eprod [NSP:Consumption]. In subhumid areas, Etroph was 46 times higher, due to a 13.7 times higher Econsump and a 3.3 times higher Eprod. In humid areas, Etroph was 5 times higher, due to a 2.5 times higher Econsump and a 2 times higher Eprod. The interannual variation of herbivore biomass, a major determinant of NSP, was 60 per cent lower in agricultural than in natural systems dominated by homeotherms, and was decoupled from the variability of precipitation. Agricultural systems reach higher NSP by [1] diverting a major proportion of ANPP from the detritus to the grazing chain, [2] converting more efficiently consumption into NSP, and [3] stabilizing herbivore biomass across years.
ISSN:1435-0629

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