Abstract
Analyses of energy efficiency in biomass production offer important insights in the context of sustainable land management and biomass production. However, much of the previous research on the topic has focused on the energy efficiency of either food or energy provision. Only recently, comprehensive analyses at the total agroecosystem level have been operationalized, studying long-term change in agroecosystem energetics in the course of the socio-ecological transition. We contribute to this line of research by offering an empirical assessment of agroecosystem energetics for the case of Austria, covering the period 1830-2010 at an annual resolution. We present a quantitative assessment of energy inputs, outputs and internal energy fluxes of Austria's agroecosystem, including crop production, livestock production and forestry, as well as energy return on investment indicators. We identify three major periods: (1) "pre-industrial land-use intensification" (1830-1914) is characterized by moderate agricultural growth based on increased biomass recirculation, declining wood harvest, and, probably, slightly declining energy returns on investments. (2) From 1918 to 1985, "industrialization of land use and the green revolution" exhibits a substitution of labor by modern energy inputs, while livestock continued to rely greatly on domestic biomass. (3) "Industrialized extensification and environmental awareness" (1986-2010) features increasing energy efficiency due to declines in livestock numbers, a shift towards forestry, and a rising amount of final products from croplands at stable energy inputs. We discuss these periods in the context of changes in both ecological impacts and social metabolism, and identify trade-offs among food and bioenergy provision.