Designing Resilient Cropping Systems.

In an ecological context, resilience refers to the ability of an ecosystem to recover from a perturbation that disrupts its natural equilibrium.  For the purposes of this lecture, however, we will extend the definition to include not only this important property but also the ability to adapt to longer term disturbances such a changing climate, the advent or adaptation of pests, and the degradation of soil quality.  Agroecosystems are highly managed ecosystems that operate far from the natural state that existed prior to their implementation.  Agricultural landscapes are highly altered in the sense that the original plant communities have been supplanted and water and nutrient cycles have been disrupted.  In many cases the hydrology of the landscape has been radically changed through irrigation or drainage.  All of these alterations have been intentional in the pursuit of creating environments that are optimized for the production of crops.  The agronomic approach is to adapt the growing environment in ways that benefit one or a few plant species.  It is this intentionality that distinguishes the management of cropping systems from natural systems and it has an important influence on their resilience to changes in the environment.  In a highly managed ecosystem, such as are most agricultural systems, the key to resilience lies in being able to adapt quickly to a changing environment.  Some environmental changes are anthropogenic and can be dealt with to some extent by altering the behaviors causing the change.  Others occur naturally, are often unforeseen and in some cases lead to disaster.  An important and often overlooked aspect of adapting to such change within an ecosystem is our own resourcefulness.  Our knowledge of the changes that are occurring, our ability to predict where they are leading, and our creativity in proposing and implementing novel management approaches are fundamental to ensuring food security for ourselves and future generations.  In the Epilogue of Crops and Man, Jack Harlan addresses the question of who’s in charge here.  His conclusion –“God help us, we are!”