Energy in a woodland-livestock agroecosystem: Prince Edward Island, Canada, 1870–2010

This article presents historic energy profiles in order to understand the changing roles of three critical energy flows in eastern Canadian agroecosystems. The first flow is the societally useful energy that farms produced in crops, animal products, and forest resources. This flow stabilized after colonization and then intensified with the introduction of fossil fuel inputs. The second flow consists of these external inputs, including human labor and the energy embodied in machinery, fuel, and fertilizers. The final flow is the biomass from within the agroecosystem itself. Farmers removed this biomass from their final produce and recycled it as feed for animals, seed for crops, and fencing for livestock management. This article presents evidence on these energy flows from a set of case studies in Northeastern North America. Prince Edward Island (PEI) offers a study of energy transitions in a frontier agroecosystem at the farm, township, county, and the bounded provincial scales. This study uses time points from the 1881, 1931, 1951, and 1996 censuses, as well other statistics. The energy in land produce remained stable during the socio-ecological transition because of the importance of forest products. Results at the sub-county scale demonstrate complementary components within the larger provincial system, and the example of one farm (1877–1892) illustrates specialized energy strategies within the advanced organic regime. After the socio-ecological transition, external inputs remained lower than expected, but together with the steady growth of livestock, they ensured that biomass energy inputs were more productive in the mineral regime than they had been in the organic period.