Ecological lessons and applications from one century of low external-input farming in the pampas of Argentina

Ecology may benefit from long term, large scale experiments on low intensity farming to test theoretical principles and convert them into practical lessons, One century of land conversion in the Argentine pampas, and its effect on critical ecological properties, were analysed and discussed. Land transformation has resulted in significant changes of land use, land cover, energy flow, nutrient dynamics, hydrology, and the trade-offs between productivity, stability and sustainability. The analytical procedure involved the complementary utilisation of different data sources and approaches. The study was focused on large geographical scales: the entire pampas and its five ecoregions. Results were interpreted under the theoretical framework of succession in ecology. The historical conversion of natural grasslands into cultivated grasslands and croplands was not homogeneous, determining a variety of land use and land cover patterns. Due to its higher productivity, much more energy, nutrients and water were mobilised in the rolling pampas than in the other ecoregions. This study provides lessons about how the energy flow, the nutrient dynamics and the hydrological process are modified by land transformation under low external-input conditions. Technical coefficients to be applied in emerging fields of environment administration such as ecological-monitoring, environmental accounting and auditing, agro-ecological certification, land evaluation and allocation, and land management, can also be supplied by this kind of studies. (C) 2001 Elsevier Science B.V. All rights reserved.