Production Range Shifts

Range shifts can occur for species of plants when climate changes displace their climatic niche. Geographic distribution creates the climatic niche that reflects the fitness of that species (through factors like temperature, precipitation etc). For agricultural crops, this climatic niche is partially fabricated through the use of genetically-modified seeds, fertilizers, and pesticides - advances in technology that made massive production possible.
Humans have removed the component of competition (that can limit the growth of an organism even in a range), and the type of niche these crops occupy is unclear. One thing does remain consistent with wild plant species: a strong link between species and optimum environment. Without the correct growing conditions, we do not yet have the ability to manipulate crop production in any environment. Drought-resistant seeds have been attempted by agricultural biotechnology corporations like Monsanto, but these have yet to be proven effective against climate changes.

The timing of life cycles is a shift that is very pertinent to the global trade of cash crops like corn and wheat. As factors like precipitation, carbon dioxide, and temperature alter the niche that crops thrive in, the biological timing of production will shift temporally. This means that harvest time will change (depending on the crop), and the timing of availability of food will follow this shift. If the life cycle shifts do not happen gradually, places without reserves could be faced with hunger and nations (like the United States) that export massive quantities of corn and wheat would be economically at-risk.

Source: Climate Impact Assessment

Chen et. al. describes the differing rate at which species will move latitudinally towards the poles and higher in elevation in order to re-capture their climatic niche. There are three main reasons for the wide variance in range shifts: time delays in species' response, individual physiological constraints, and interacting drivers of change. These are all applicable to corn and wheat as the environment best suited for their production is changing.
Species response may vary according to physiological factors, causing differential change in farm success. Monocultures are high-risk operations: if the crop is physiologically constrained, the entire vested interest is lost. Since corn and wheat are specifically planted each season, a range shift cannot physically occur. However, the concept of range shifts is very important in relation to agriculture because the success or failure of crops will determine the shift in growing ability. A human-driven range shift will occur as some regions grow wheat successfully, for example, while others cannot. The agribusiness giant Cargill Inc. is "investing in northern U.S. facilities, anticipating increased grain production in that part of the country" (Bjerga). Losses in some areas will mean gains in others as the crops will shift towards the regions now suited for their physiological needs. This is a dynamic system constantly being influenced by interacting drivers of change that will pose tricky scenarios for corn and wheat farmers.